1
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Williams FN, Travis KL, Haver HN, Umano AD, Guerra-Hernandez Y, Scaglione KM. Acute stress and multicellular development alter the solubility of the Dictyostelium Sup35 ortholog ERF3. Microbiol Spectr 2024:e0160724. [PMID: 39345220 DOI: 10.1128/spectrum.01607-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2024] [Accepted: 08/26/2024] [Indexed: 10/01/2024] Open
Abstract
Among sequenced organisms, the genome of Dictyostelium discoideum is unique in that it encodes for a massive amount of repeat-rich sequences in the coding region of genes. This results in the Dictyostelium proteome encoding for thousands of repeat-rich proteins, with nearly 24% of the Dictyostelium proteome encoding Q/N-rich regions that are predicted to be prion like in nature. To begin investigating the role of prion-like proteins in Dictyostelium, we decided to investigate ERF3, the Dictyostelium ortholog of the well-characterized yeast prion protein Sup35. ERF3 lacks the Q/N-rich region required for prion formation in yeast, raising the question of whether this protein aggregates and has prion-like properties in Dictyostelium. Here, we found that ERF3 formed aggregates in response to acute cellular stress. However, unlike bona fide prions, we were unable to detect transmission of aggregates to progeny. We further found that aggregation of this protein is driven by the ordered C-terminal domain independently of the disordered N-terminal domain. Finally, we also observed aggregation of ERF3 under conditions that induce multicellular development, suggesting that this phenomenon may play a role in Dictyostelium development. Together, these findings suggest a role for regulated protein aggregation in Dictyostelium cells under stress and during development.IMPORTANCEPrion-like proteins have both beneficial and deleterious effects on cellular health, and many organisms have evolved distinct mechanisms to regulate the behaviors of these proteins. The social amoeba Dictyostelium discoideum contains the highest proportion of proteins predicted to be prion like and has mechanisms to suppress their aggregation. However, the potential roles and regulation of these proteins remain largely unknown. Here, we demonstrate that aggregation of the Dictyostelium translation termination factor ERF3 is induced by both acute cellular stress and by multicellular development. These findings imply that protein aggregation may have a regulated and functional role in the Dictyostelium stress response and during multicellular development.
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Affiliation(s)
- Felicia N Williams
- Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, USA
| | - Kanesha L Travis
- Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, USA
| | - Holly N Haver
- Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, USA
| | - Anna D Umano
- Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, USA
| | - Yaneli Guerra-Hernandez
- Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, USA
| | - K Matthew Scaglione
- Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, USA
- Center for Neurodegeneration and Neurotherapeutics, Duke University, Durham, North Carolina, USA
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2
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Jonischkies K, del Angel M, Demiray YE, Loaiza Zambrano A, Stork O. The NDR family of kinases: essential regulators of aging. Front Mol Neurosci 2024; 17:1371086. [PMID: 38803357 PMCID: PMC11129689 DOI: 10.3389/fnmol.2024.1371086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Accepted: 04/22/2024] [Indexed: 05/29/2024] Open
Abstract
Aging is defined as a progressive decline of cognitive and physiological functions over lifetime. Since the definition of the nine hallmarks of aging in 2013 by López-Otin, numerous studies have attempted to identify the main regulators and contributors in the aging process. One interesting group of proteins whose participation has been implicated in several aging hallmarks are the nuclear DBF2-related (NDR) family of serine-threonine AGC kinases. They are one of the core components of the Hippo signaling pathway and include NDR1, NDR2, LATS1 and LATS2 in mammals, along with its highly conserved metazoan orthologs; Trc in Drosophila melanogaster, SAX-1 in Caenorhabditis elegans, CBK1, DBF20 in Saccharomyces cerevisiae and orb6 in Saccharomyces pombe. These kinases have been independently linked to the regulation of widely diverse cellular processes disrupted during aging such as the cell cycle progression, transcription, intercellular communication, nutrient homeostasis, autophagy, apoptosis, and stem cell differentiation. However, a comprehensive overview of the state-of-the-art knowledge regarding the post-translational modifications of and by NDR kinases in aging has not been conducted. In this review, we summarize the current understanding of the NDR family of kinases, focusing on their relevance to various aging hallmarks, and emphasize the growing body of evidence that suggests NDR kinases are essential regulators of aging across species.
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Affiliation(s)
- Kevin Jonischkies
- Department of Genetics and Molecular Neurobiology, Institute of Biology, Otto-von-Guericke University Magdeburg, Magdeburg, Germany
| | - Miguel del Angel
- Department of Genetics and Molecular Neurobiology, Institute of Biology, Otto-von-Guericke University Magdeburg, Magdeburg, Germany
| | - Yunus Emre Demiray
- Department of Genetics and Molecular Neurobiology, Institute of Biology, Otto-von-Guericke University Magdeburg, Magdeburg, Germany
| | - Allison Loaiza Zambrano
- Department of Genetics and Molecular Neurobiology, Institute of Biology, Otto-von-Guericke University Magdeburg, Magdeburg, Germany
| | - Oliver Stork
- Department of Genetics and Molecular Neurobiology, Institute of Biology, Otto-von-Guericke University Magdeburg, Magdeburg, Germany
- Center for Behavioral Brain Science, Magdeburg, Germany
- Center for Intervention and Research on Adaptive and Maladaptive Brain Circuits Underlying Mental Health (C-I-R-C), Jena-Magdeburg-Halle, Germany
- German Center for Mental Health (DZPG), Jena-Magdeburg-Halle, Germany
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3
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Podvin S, Rosenthal SB, Poon W, Wei E, Fisch KM, Hook V. Mutant Huntingtin Protein Interaction Map Implicates Dysregulation of Multiple Cellular Pathways in Neurodegeneration of Huntington's Disease. J Huntingtons Dis 2022; 11:243-267. [PMID: 35871359 PMCID: PMC9484122 DOI: 10.3233/jhd-220538] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Huntington's disease (HD) is a genetic neurodegenerative disease caused by trinucleotide repeat (CAG) expansions in the human HTT gene encoding the huntingtin protein (Htt) with an expanded polyglutamine tract. OBJECTIVE HD models from yeast to transgenic mice have investigated proteins interacting with mutant Htt that may initiate molecular pathways of cell death. There is a paucity of datasets of published Htt protein interactions that include the criteria of 1) defining fragments or full-length Htt forms, 2) indicating the number of poly-glutamines of the mutant and wild-type Htt forms, and 3) evaluating native Htt interaction complexes. This research evaluated such interactor data to gain understanding of Htt dysregulation of cellular pathways. METHODS Htt interacting proteins were compiled from the literature that meet our criteria and were subjected to network analysis via clustering, gene ontology, and KEGG pathways using rigorous statistical methods. RESULTS The compiled data of Htt interactors found that both mutant and wild-type Htt interact with more than 2,971 proteins. Application of a community detection algorithm to all known Htt interactors identified significant signal transduction, membrane trafficking, chromatin, and mitochondrial clusters, among others. Binomial analyses of a subset of reported protein interactor information determined that chromatin organization, signal transduction and endocytosis were diminished, while mitochondria, translation and membrane trafficking had enriched overall edge effects. CONCLUSION The data support the hypothesis that mutant Htt disrupts multiple cellular processes causing toxicity. This dataset is an open resource to aid researchers in formulating hypotheses of HD mechanisms of pathogenesis.
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Affiliation(s)
- Sonia Podvin
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, USA
| | - Sara Brin Rosenthal
- Center for Computational Biology & Bioinformatics, University of California, San Diego, La Jolla, CA, USA
| | - William Poon
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, USA
| | - Enlin Wei
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, USA
| | - Kathleen M Fisch
- Center for Computational Biology & Bioinformatics, University of California, San Diego, La Jolla, CA, USA.,Department of Obstetrics, Gynecology & Reproductive Sciences, University of California, San Diego, La Jolla, CA, USA
| | - Vivian Hook
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, USA.,Department of Neuroscience and Dept of Pharmacology, School of Medicine, University of California, San Diego, La Jolla, CA, USA
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4
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Lin LTW, Razzaq A, Di Gregorio SE, Hong S, Charles B, Lopes MH, Beraldo F, Prado VF, Prado MAM, Duennwald ML. Hsp90 and its co-chaperone Sti1 control TDP-43 misfolding and toxicity. FASEB J 2021; 35:e21594. [PMID: 33908654 DOI: 10.1096/fj.202002645r] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 03/15/2021] [Accepted: 03/30/2021] [Indexed: 12/14/2022]
Abstract
Protein misfolding is a central feature of most neurodegenerative diseases. Molecular chaperones can modulate the toxicity associated with protein misfolding, but it remains elusive which molecular chaperones and co-chaperones interact with specific misfolded proteins. TDP-43 misfolding and inclusion formation are a hallmark of amyotrophic lateral sclerosis (ALS) and other neurodegenerative diseases. Using yeast and mammalian neuronal cells we find that Hsp90 and its co-chaperone Sti1 have the capacity to alter TDP-43 misfolding, inclusion formation, aggregation, and cellular toxicity. Our data also demonstrate that impaired Hsp90 function sensitizes cells to TDP-43 toxicity and that Sti1 specifically interacts with and strongly modulates TDP-43 toxicity in a dose-dependent manner. Our study thus uncovers a previously unrecognized tie between Hsp90, Sti1, TDP-43 misfolding, and cellular toxicity.
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Affiliation(s)
- Lilian Tsai-Wei Lin
- Department of Pathology and Laboratory Medicine, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Abdul Razzaq
- Robarts Research Institute, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Sonja E Di Gregorio
- Department of Pathology and Laboratory Medicine, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Soojie Hong
- Department of Pathology and Laboratory Medicine, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Brendan Charles
- Department of Pathology and Laboratory Medicine, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Marilene H Lopes
- Robarts Research Institute, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada.,Department of Anatomy & Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada.,Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Flavio Beraldo
- Robarts Research Institute, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Vania F Prado
- Robarts Research Institute, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada.,Department of Anatomy & Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Marco A M Prado
- Robarts Research Institute, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada.,Department of Anatomy & Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Martin L Duennwald
- Department of Pathology and Laboratory Medicine, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada.,Department of Anatomy & Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
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5
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Pinheiro GMS, Amorim GC, Iqbal A, Ramos CHI, Almeida FCL. 1H, 15N and 13C resonance assignments of the J-domain of co-chaperone Sis1 from Saccharomyces cerevisiae. BIOMOLECULAR NMR ASSIGNMENTS 2018; 12:279-281. [PMID: 29713947 DOI: 10.1007/s12104-018-9823-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 04/24/2018] [Indexed: 06/08/2023]
Abstract
Protein folding in the cell is usually aided by molecular chaperones, from which the Hsp70 (Hsp = heat shock protein) family has many important roles, such as aiding nascent folding and participating in translocation. Hsp70 has ATPase activity which is stimulated by binding to the J-domain present in co-chaperones from the Hsp40 family. Hsp40s have many functions, as for instance the binding to partially folded proteins to be delivered to Hsp70. However, the presence of the J-domain characterizes Hsp40s or, by this reason, as J-proteins. The J-domain alone can stimulate Hsp70 ATPase activity. Apparently, it also maintains the same conformation as in the whole protein although structural information on full J-proteins is still missing. This work reports the 1H, 15N and 13C resonance assignments of the J-domain of a Hsp40 from Saccharomyces cerevisiae, named Sis1. Secondary structure and order parameter prediction from chemical shifts are also reported. Altogether, the data show that Sis1 J-domain is highly structured and predominantly formed by α-helices, results that are in very good agreement with those previously reported for the crystallographic structure.
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Affiliation(s)
| | - Gisele C Amorim
- National Center for Structural Biology and Bioimaging (CENABIO)/National Center for Nuclear Magnetic Resonance (CNRMN), Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Numpex-Bio - Federal University of Rio de Janeiro, Duque de Caxias, RJ, Brazil
| | - Anwar Iqbal
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- National Center for Structural Biology and Bioimaging (CENABIO)/National Center for Nuclear Magnetic Resonance (CNRMN), Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - C H I Ramos
- Institute of Chemistry, University of Campinas UNICAMP, Campinas, SP, Brazil.
| | - Fabio C L Almeida
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
- National Center for Structural Biology and Bioimaging (CENABIO)/National Center for Nuclear Magnetic Resonance (CNRMN), Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
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6
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Ohkuni K, Pasupala N, Peek J, Holloway GL, Sclar GD, Levy-Myers R, Baker RE, Basrai MA, Kerscher O. SUMO-Targeted Ubiquitin Ligases (STUbLs) Reduce the Toxicity and Abnormal Transcriptional Activity Associated With a Mutant, Aggregation-Prone Fragment of Huntingtin. Front Genet 2018; 9:379. [PMID: 30279700 PMCID: PMC6154015 DOI: 10.3389/fgene.2018.00379] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 08/27/2018] [Indexed: 01/01/2023] Open
Abstract
Cell viability and gene expression profiles are altered in cellular models of neurodegenerative disorders such as Huntington’s Disease (HD). Using the yeast model system, we show that the SUMO-targeted ubiquitin ligase (STUbL) Slx5 reduces the toxicity and abnormal transcriptional activity associated with a mutant, aggregation-prone fragment of huntingtin (Htt), the causative agent of HD. We demonstrate that expression of an aggregation-prone Htt construct with 103 glutamine residues (103Q), but not the non-expanded form (25Q), results in severe growth defects in slx5Δ and slx8Δ cells. Since Slx5 is a nuclear protein and because Htt expression affects gene transcription, we assessed the effect of STUbLs on the transcriptional properties of aggregation-prone Htt. Expression of Htt 25Q and 55Q fused to the Gal4 activation domain (AD) resulted in reporter gene auto-activation. Remarkably, the auto-activation of Htt constructs was abolished by expression of Slx5 fused to the Gal4 DNA-binding domain (BD-Slx5). In support of these observations, RNF4, the human ortholog of Slx5, curbs the aberrant transcriptional activity of aggregation-prone Htt in yeast and a variety of cultured human cell lines. Functionally, we find that an extra copy of SLX5 specifically reduces Htt aggregates in the cytosol as well as chromatin-associated Htt aggregates in the nucleus. Finally, using RNA sequencing, we identified and confirmed specific targets of Htt’s transcriptional activity that are modulated by Slx5. In summary, this study of STUbLs uncovers a conserved pathway that counteracts the accumulation of aggregating, transcriptionally active Htt (and possibly other poly-glutamine expanded proteins) on chromatin in both yeast and in mammalian cells.
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Affiliation(s)
- Kentaro Ohkuni
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
| | - Nagesh Pasupala
- Biology Department, College of William & Mary, Williamsburg, VA, United States
| | - Jennifer Peek
- Biology Department, College of William & Mary, Williamsburg, VA, United States
| | | | - Gloria D Sclar
- Biology Department, College of William & Mary, Williamsburg, VA, United States
| | - Reuben Levy-Myers
- Biology Department, College of William & Mary, Williamsburg, VA, United States
| | - Richard E Baker
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA, United States
| | - Munira A Basrai
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
| | - Oliver Kerscher
- Biology Department, College of William & Mary, Williamsburg, VA, United States
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7
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Boland B, Yu WH, Corti O, Mollereau B, Henriques A, Bezard E, Pastores GM, Rubinsztein DC, Nixon RA, Duchen MR, Mallucci GR, Kroemer G, Levine B, Eskelinen EL, Mochel F, Spedding M, Louis C, Martin OR, Millan MJ. Promoting the clearance of neurotoxic proteins in neurodegenerative disorders of ageing. Nat Rev Drug Discov 2018; 17:660-688. [PMID: 30116051 DOI: 10.1038/nrd.2018.109] [Citation(s) in RCA: 335] [Impact Index Per Article: 55.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Neurodegenerative disorders of ageing (NDAs) such as Alzheimer disease, Parkinson disease, frontotemporal dementia, Huntington disease and amyotrophic lateral sclerosis represent a major socio-economic challenge in view of their high prevalence yet poor treatment. They are often called 'proteinopathies' owing to the presence of misfolded and aggregated proteins that lose their physiological roles and acquire neurotoxic properties. One reason underlying the accumulation and spread of oligomeric forms of neurotoxic proteins is insufficient clearance by the autophagic-lysosomal network. Several other clearance pathways are also compromised in NDAs: chaperone-mediated autophagy, the ubiquitin-proteasome system, extracellular clearance by proteases and extrusion into the circulation via the blood-brain barrier and glymphatic system. This article focuses on emerging mechanisms for promoting the clearance of neurotoxic proteins, a strategy that may curtail the onset and slow the progression of NDAs.
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Affiliation(s)
- Barry Boland
- Department of Pharmacology and Therapeutics, University College Cork, Cork, Ireland
| | - Wai Haung Yu
- Department of Pathology and Cell Biology, Taub Institute for Alzheimer's Disease Research, Columbia University, New York, NY, USA
| | - Olga Corti
- ICM Institute for Brain and Spinal Cord, Paris, France
| | | | | | - Erwan Bezard
- CNRS, Institut des Maladies Neurodégénératives, Bordeaux, France
| | - Greg M Pastores
- Department of Metabolic Diseases, Mater Misericordiae University Hospital, Dublin, Ireland
| | - David C Rubinsztein
- Department of Medical Genetics, Cambridge Institute for Medical Research, University of Cambridge and UK Dementia Research Institute, Cambridge Biomedical Campus, Cambridge, UK
| | - Ralph A Nixon
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, NY, USA.,Departments of Psychiatry and Cell Biology, New York University School of Medicine, New York, NY, USA
| | - Michael R Duchen
- UCL Consortium for Mitochondrial Research and Department of Cell and Developmental Biology, University College London, London, UK
| | - Giovanna R Mallucci
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Guido Kroemer
- Université Paris Descartes/Paris V, Sorbonne Paris Cité, Paris, France.,Université Pierre et Marie Curie/Paris VI, Paris, France.,Equipe 11 labellisée Ligue contre le Cancer, Centre de Recherche des Cordeliers, Paris, France.,INSERM U1138, Paris, France.,Metabolomics and Cell Biology Platforms, Gustave Roussy Comprehensive Cancer Institute, Villejuif, France.,Karolinska Institute, Department of Women's and Children's Health, Karolinska University Hospital, Stockholm, Sweden.,Pôle de Biologie, Hopitâl Européen George Pompidou (AP-HP), Paris, France
| | - Beth Levine
- Center for Autophagy Research, University of Texas Southwestern Medical Center, Dallas, TX, USA.,Howard Hughes Medical Institute, Dallas, TX, USA
| | | | - Fanny Mochel
- INSERM U 1127, Brain and Spine Institute, Paris, France
| | | | - Caroline Louis
- Centre for Therapeutic Innovation in Neuropsychiatry, IDR Servier, 78290 Croissy sur Seine, France
| | - Olivier R Martin
- Université d'Orléans & CNRS, Institut de Chimie Organique et Analytique (ICOA), Orléans, France
| | - Mark J Millan
- Centre for Therapeutic Innovation in Neuropsychiatry, IDR Servier, 78290 Croissy sur Seine, France
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8
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Zhao Y, Zurawel AA, Jenkins NP, Duennwald ML, Cheng C, Kettenbach AN, Supattapone S. Comparative Analysis of Mutant Huntingtin Binding Partners in Yeast Species. Sci Rep 2018; 8:9554. [PMID: 29934597 PMCID: PMC6015068 DOI: 10.1038/s41598-018-27900-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 06/12/2018] [Indexed: 12/21/2022] Open
Abstract
Huntington's disease is caused by the pathological expansion of a polyglutamine (polyQ) stretch in Huntingtin (Htt), but the molecular mechanisms by which polyQ expansion in Htt causes toxicity in selective neuronal populations remain poorly understood. Interestingly, heterologous expression of expanded polyQ Htt is toxic in Saccharomyces cerevisiae cells, but has no effect in Schizosaccharomyces pombe, a related yeast species possessing very few endogenous polyQ or Q/N-rich proteins. Here, we used a comprehensive and unbiased mass spectrometric approach to identify proteins that bind Htt in a length-dependent manner in both species. Analysis of the expanded polyQ-associated proteins reveals marked enrichment of proteins that are localized to and play functional roles in nucleoli and mitochondria in S. cerevisiae, but not in S. pombe. Moreover, expanded polyQ Htt appears to interact preferentially with endogenous polyQ and Q/N-rich proteins, which are rare in S. pombe, as well as proteins containing coiled-coil motifs in S. cerevisiae. Taken together, these results suggest that polyQ expansion of Htt may cause cellular toxicity in S. cerevisiae by sequestering endogenous polyQ and Q/N-rich proteins, particularly within nucleoli and mitochondria.
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Affiliation(s)
- Yanding Zhao
- Departments of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth College, Hanover, New Hampshire, 03755, United States
| | - Ashley A Zurawel
- Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, New Hampshire, 03755, United States
| | - Nicole P Jenkins
- Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, New Hampshire, 03755, United States
| | - Martin L Duennwald
- Department of Pathology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, N6A 5C1, Canada
| | - Chao Cheng
- Departments of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth College, Hanover, New Hampshire, 03755, United States
- Biomedical Data Sciences, Geisel School of Medicine at Dartmouth College, Hanover, New Hampshire, 03755, United States
| | - Arminja N Kettenbach
- Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, New Hampshire, 03755, United States
| | - Surachai Supattapone
- Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, New Hampshire, 03755, United States.
- Medicine, Geisel School of Medicine at Dartmouth College, Hanover, New Hampshire, 03755, United States.
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9
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Kayatekin C, Amasino A, Gaglia G, Flannick J, Bonner JM, Fanning S, Narayan P, Barrasa MI, Pincus D, Landgraf D, Nelson J, Hesse WR, Costanzo M, Myers CL, Boone C, Florez JC, Lindquist S. Translocon Declogger Ste24 Protects against IAPP Oligomer-Induced Proteotoxicity. Cell 2018; 173:62-73.e9. [PMID: 29526462 PMCID: PMC5945206 DOI: 10.1016/j.cell.2018.02.026] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 11/20/2017] [Accepted: 02/08/2018] [Indexed: 10/17/2022]
Abstract
Aggregates of human islet amyloid polypeptide (IAPP) in the pancreas of patients with type 2 diabetes (T2D) are thought to contribute to β cell dysfunction and death. To understand how IAPP harms cells and how this might be overcome, we created a yeast model of IAPP toxicity. Ste24, an evolutionarily conserved protease that was recently reported to degrade peptides stuck within the translocon between the cytoplasm and the endoplasmic reticulum, was the strongest suppressor of IAPP toxicity. By testing variants of the human homolog, ZMPSTE24, with varying activity levels, the rescue of IAPP toxicity proved to be directly proportional to the declogging efficiency. Clinically relevant ZMPSTE24 variants identified in the largest database of exomes sequences derived from T2D patients were characterized using the yeast model, revealing 14 partial loss-of-function variants, which were enriched among diabetes patients over 2-fold. Thus, clogging of the translocon by IAPP oligomers may contribute to β cell failure.
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Affiliation(s)
- Can Kayatekin
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA.
| | - Audra Amasino
- Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Giorgio Gaglia
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Jason Flannick
- Programs in Metabolism and Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Center for Human Genetic Research, Department of Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Julia M Bonner
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Saranna Fanning
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Priyanka Narayan
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | | | - David Pincus
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Dirk Landgraf
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Justin Nelson
- Bioinformatics and Computational Biology Graduate Program, University of Minnesota-Twin Cities, Minneapolis, MN 55455, USA
| | - William R Hesse
- Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Michael Costanzo
- Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Chad L Myers
- Department of Computer Science and Engineering, University of Minnesota-Twin Cities, Minneapolis, MN 55455, USA
| | - Charles Boone
- Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Jose C Florez
- Programs in Metabolism and Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Center for Human Genetic Research, Department of Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Diabetes Research Center, Diabetes Unit, Department of Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Medicine, Harvard Medical School, Boston, MA 02114, USA
| | - Susan Lindquist
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Massachusetts Institute of Technology, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Cambridge, MA 02139, USA
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10
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Brehme M, Voisine C. Model systems of protein-misfolding diseases reveal chaperone modifiers of proteotoxicity. Dis Model Mech 2017; 9:823-38. [PMID: 27491084 PMCID: PMC5007983 DOI: 10.1242/dmm.024703] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Chaperones and co-chaperones enable protein folding and degradation, safeguarding the proteome against proteotoxic stress. Chaperones display dynamic responses to exogenous and endogenous stressors and thus constitute a key component of the proteostasis network (PN), an intricately regulated network of quality control and repair pathways that cooperate to maintain cellular proteostasis. It has been hypothesized that aging leads to chronic stress on the proteome and that this could underlie many age-associated diseases such as neurodegeneration. Understanding the dynamics of chaperone function during aging and disease-related proteotoxic stress could reveal specific chaperone systems that fail to respond to protein misfolding. Through the use of suppressor and enhancer screens, key chaperones crucial for proteostasis maintenance have been identified in model organisms that express misfolded disease-related proteins. This review provides a literature-based analysis of these genetic studies and highlights prominent chaperone modifiers of proteotoxicity, which include the HSP70-HSP40 machine and small HSPs. Taken together, these studies in model systems can inform strategies for therapeutic regulation of chaperone functionality, to manage aging-related proteotoxic stress and to delay the onset of neurodegenerative diseases.
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Affiliation(s)
- Marc Brehme
- Joint Research Center for Computational Biomedicine (JRC-COMBINE), RWTH Aachen University, 52062 Aachen, Germany
| | - Cindy Voisine
- Department of Biology, Northeastern Illinois University, Chicago, IL 60625, USA
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11
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Berglund LL, Hao X, Liu B, Grantham J, Nyström T. Differential effects of soluble and aggregating polyQ proteins on cytotoxicity and type-1 myosin-dependent endocytosis in yeast. Sci Rep 2017; 7:11328. [PMID: 28900136 PMCID: PMC5595923 DOI: 10.1038/s41598-017-11102-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 08/17/2017] [Indexed: 11/19/2022] Open
Abstract
Huntington’s disease develops when the polyglutamine (polyQ) repeat in the Huntingtin (Htt) protein is expanded to over 35 glutamines rendering it aggregation-prone. Here, using Htt exon-1 as a polyQ model protein in a genome-wide screen in yeast, we show that the normal and soluble Htt exon-1 is toxic in cells with defects in type-1 myosin-dependent endocytosis. The toxicity of Htt is linked to physical interactions with type-1 myosins, which occur via the Htt proline-rich region, leading to a reduction in actin patch polarization and clathrin-dependent endocytosis. An expansion of the polyQ stretch from 25 to 103 glutamines, which causes Htt aggregation, alleviated Htt toxicity in cells lacking Myo5 or other components involved in early endocytosis. The data suggest that the proline-rich stretch of Htt interacts with type-1 myosin/clathrin-dependent processes and demonstrate that a reduction in the activity of such processes may result in a positive selection for polyQ expansions.
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Affiliation(s)
- Lisa L Berglund
- Institute of Biomedicine - Department of Microbiology & Immunology, Sahlgrenska Academy, University of Gothenburg, Medicinaregatan 7A, 405 30, Göteborg, Sweden
| | - Xinxin Hao
- Institute of Biomedicine - Department of Microbiology & Immunology, Sahlgrenska Academy, University of Gothenburg, Medicinaregatan 7A, 405 30, Göteborg, Sweden
| | - Beidong Liu
- Department of Chemistry and Molecular Biology, University of Gothenburg, Medicinaregatan 9C, 405 30, Göteborg, Sweden
| | - Julie Grantham
- Department of Chemistry and Molecular Biology, University of Gothenburg, Medicinaregatan 9C, 405 30, Göteborg, Sweden
| | - Thomas Nyström
- Institute of Biomedicine - Department of Microbiology & Immunology, Sahlgrenska Academy, University of Gothenburg, Medicinaregatan 7A, 405 30, Göteborg, Sweden.
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12
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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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13
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Zurawel AA, Kabeche R, DiGregorio SE, Deng L, Menon KM, Opalko H, Duennwald ML, Moseley JB, Supattapone S. CAG Expansions Are Genetically Stable and Form Nontoxic Aggregates in Cells Lacking Endogenous Polyglutamine Proteins. mBio 2016; 7:e01367-16. [PMID: 27677791 PMCID: PMC5040113 DOI: 10.1128/mbio.01367-16] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 09/06/2016] [Indexed: 11/20/2022] Open
Abstract
Proteins containing polyglutamine (polyQ) regions are found in almost all eukaryotes, albeit with various frequencies. In humans, proteins such as huntingtin (Htt) with abnormally expanded polyQ regions cause neurodegenerative diseases such as Huntington's disease (HD). To study how the presence of endogenous polyQ aggregation modulates polyQ aggregation and toxicity, we expressed polyQ expanded Htt fragments (polyQ Htt) in Schizosaccharomyces pombe In stark contrast to other unicellular fungi, such as Saccharomyces cerevisiae, S. pombe is uniquely devoid of proteins with more than 10 Q repeats. We found that polyQ Htt forms aggregates within S. pombe cells only with exceedingly long polyQ expansions. Surprisingly, despite the presence of polyQ Htt aggregates in both the cytoplasm and nucleus, no significant growth defect was observed in S. pombe cells. Further, PCR analysis showed that the repetitive polyQ-encoding DNA region remained constant following transformation and after multiple divisions in S. pombe, in contrast to the genetic instability of polyQ DNA sequences in other organisms. These results demonstrate that cells with a low content of polyQ or other aggregation-prone proteins can show a striking resilience with respect to polyQ toxicity and that genetic instability of repetitive DNA sequences may have played an important role in the evolutionary emergence and exclusion of polyQ expansion proteins in different organisms. IMPORTANCE Polyglutamine (polyQ) proteins encoded by repetitive CAG DNA sequences serve a variety of normal biological functions. Yet some proteins with abnormally expanded polyQ regions cause neurodegeneration through unknown mechanisms. To study how distinct cellular environments modulate polyQ aggregation and toxicity, we expressed CAG-expanded huntingtin fragments in Schizosaccharomyces pombe In stark contrast to many other eukaryotes, S. pombe is uniquely devoid of proteins containing long polyQ tracts. Our results show that S. pombe cells, despite their low content of endogenous polyQ proteins, exhibit striking and unexpected resilience with respect to polyQ toxicity and that genetic instability of repetitive DNA sequences may have played an important role in the emergence and expansion of polyQ domains in eukaryotic evolution.
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Affiliation(s)
- Ashley A Zurawel
- Department of Biochemistry, Geisel School of Medicine at Dartmouth College, Hanover, New Hampshire, USA
| | - Ruth Kabeche
- Department of Biochemistry, Geisel School of Medicine at Dartmouth College, Hanover, New Hampshire, USA
| | - Sonja E DiGregorio
- Department of Pathology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Lin Deng
- Department of Biochemistry, Geisel School of Medicine at Dartmouth College, Hanover, New Hampshire, USA
| | - Kartikeya M Menon
- Department of Biochemistry, Geisel School of Medicine at Dartmouth College, Hanover, New Hampshire, USA
| | - Hannah Opalko
- Department of Biochemistry, Geisel School of Medicine at Dartmouth College, Hanover, New Hampshire, USA
| | - Martin L Duennwald
- Department of Pathology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - James B Moseley
- Department of Biochemistry, Geisel School of Medicine at Dartmouth College, Hanover, New Hampshire, USA
| | - Surachai Supattapone
- Department of Biochemistry, Geisel School of Medicine at Dartmouth College, Hanover, New Hampshire, USA Department of Medicine, Geisel School of Medicine at Dartmouth College, Hanover, New Hampshire, USA
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14
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Yang J, Hao X, Cao X, Liu B, Nyström T. Spatial sequestration and detoxification of Huntingtin by the ribosome quality control complex. eLife 2016; 5. [PMID: 27033550 PMCID: PMC4868537 DOI: 10.7554/elife.11792] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 03/02/2016] [Indexed: 11/13/2022] Open
Abstract
Huntington disease (HD) is a neurological disorder caused by polyglutamine expansions in mutated Huntingtin (mHtt) proteins, rendering them prone to form inclusion bodies (IB). We report that in yeast, such IB formation is a factor-dependent process subjected to age-related decline. A genome-wide, high-content imaging approach, identified the E3 ubiquitin ligase, Ltn1 of the ribosome quality control complex (RQC) as a key factor required for IB formation, ubiquitination, and detoxification of model mHtt. The failure of ltn1∆ cells to manage mHtt was traced to another RQC component, Tae2, and inappropriate control of heat shock transcription factor, Hsf1, activity. Moreover, super-resolution microscopy revealed that mHtt toxicity in RQC-deficient cells was accompanied by multiple mHtt aggregates altering actin cytoskeletal structures and retarding endocytosis. The data demonstrates that spatial sequestration of mHtt into IBs is policed by the RQC-Hsf1 regulatory system and that such compartmentalization, rather than ubiquitination, is key to mHtt detoxification. DOI:http://dx.doi.org/10.7554/eLife.11792.001 Huntington’s disease is a neurological disease that is caused by mutations in the gene that encodes a protein called Htt. Individuals with this mutation gradually lose neurons as they age, resulting in declines in muscle coordination and mental abilities. The mutant Htt proteins tend to form clumps inside cells, but it is not clear if these clumps are the cause of the disease symptoms or whether they have a protective effect. Yang et al. used yeast as a model to investigate whether the mutant Htt proteins need other molecules to allow them to form clumps. The experiments identified several new molecules that are required for mutated Htt to form clumps. Some of these are components of a system called the Ribosome Quality Control (RQC) complex, which monitors newly made proteins and labels abnormal ones for destruction. However, Yang et al.’s findings suggest that the RQC complex regulates the formation of Htt clumps through a different pathway involving a protein called heat shock factor 1. In this case, cells would need to fine-tune heat shock factor 1 activity to make mutant Htt proteins clump together to protect cells from damage. Future experiments should expand Yang et al.’s findings to animal models of Huntington’s disease and identify which other molecules contribute to the formation of Htt clumps. One challenge will be to find out why older neurons fail to form clumps of Htt proteins, and whether this can be overcome by drugs that boost the activity of the molecules that Yang et al. identified. DOI:http://dx.doi.org/10.7554/eLife.11792.002
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Affiliation(s)
- Junsheng Yang
- Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden
| | - Xinxin Hao
- Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden
| | - Xiuling Cao
- Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden
| | - Beidong Liu
- Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden
| | - Thomas Nyström
- Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden
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15
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O’Rourke TW, Reines D. Determinants of Amyloid Formation for the Yeast Termination Factor Nab3. PLoS One 2016; 11:e0150865. [PMID: 26954508 PMCID: PMC4783047 DOI: 10.1371/journal.pone.0150865] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 02/19/2016] [Indexed: 01/01/2023] Open
Abstract
Low complexity protein sequences are often intrinsically unstructured and many have the potential to polymerize into amyloid aggregates including filaments and hydrogels. RNA-binding proteins are unusually enriched in such sequences raising the question as to what function these domains serve in RNA metabolism. One such yeast protein, Nab3, is an 802 amino acid termination factor that contains an RNA recognition motif and a glutamine/proline rich domain adjacent to a region with structural similarity to a human hnRNP. A portion of the C-terminal glutamine/proline-rich domain assembles into filaments that organize into a hydrogel. Here we analyze the determinants of filament formation of the isolated low complexity domain as well as examine the polymerization properties of full-length Nab3. We found that the C-terminal region with structural homology to hnRNP-C is not required for assembly, nor is an adjacent stretch of 16 glutamines. However, reducing the overall glutamine composition of this 134-amino acid segment from 32% to 14% destroys its polymerization ability. Importantly, full-length wildtype Nab3 also formed filaments with a characteristic cross-β structure which was dependent upon the glutamine/proline-rich region. When full length Nab3 with reduced glutamine content in its low complexity domain was exchanged for wildtype Nab3, cells were not viable. This suggests that polymerization of Nab3 is normally required for its function. In an extension of this idea, we show that the low complexity domain of another yeast termination factor, Pcf11, polymerizes into amyloid fibers and a hydrogel. These findings suggest that, like many other RNA binding proteins, termination factors share a common biophysical trait that may be important for their function.
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Affiliation(s)
- Thomas W. O’Rourke
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Daniel Reines
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, United States of America
- * E-mail:
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16
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Serpionov GV, Alexandrov AI, Antonenko YN, Ter-Avanesyan MD. A protein polymerization cascade mediates toxicity of non-pathological human huntingtin in yeast. Sci Rep 2015; 5:18407. [PMID: 26673834 PMCID: PMC4682096 DOI: 10.1038/srep18407] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 11/18/2015] [Indexed: 12/21/2022] Open
Abstract
Several neurodegenerative amyloidoses, including Huntington disease, are caused by expansion of polyglutamine (polyQ) stretches in otherwise unrelated proteins. In a yeast model, an N-terminal fragment of mutant huntingtin with a stretch of 103 glutamine residues aggregates and causes toxicity, while its non-toxic wild type variant with a sequence of 25 glutamines (Htt25Q) does not aggregate. Here, we observed that non-toxic polymers of various proteins with glutamine-rich domains could seed polymerization of Htt25Q, which caused toxicity by seeding polymerization of the glutamine/asparagine-rich Sup35 protein thus depleting the soluble pools of this protein and its interacting partner, Sup45. Importantly, only polymers of Htt25Q, but not of the initial benign polymers, induced Sup35 polymerization, indicating an intermediary role of Htt25Q in cross-seeding Sup35 polymerization. These data provide a novel insight into interactions between amyloidogenic proteins and suggest a possible role for these interactions in the pathogenesis of Huntington and other polyQ diseases.
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Affiliation(s)
- Genrikh V Serpionov
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences. 33, bld. 2 Leninsky Ave., Moscow 119071, Russia
| | - Alexander I Alexandrov
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences. 33, bld. 2 Leninsky Ave., Moscow 119071, Russia
| | - Yuri N Antonenko
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie gori, 1, bldg. 40, Moscow 119991, Russia
| | - Michael D Ter-Avanesyan
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences. 33, bld. 2 Leninsky Ave., Moscow 119071, Russia
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17
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Mokry DZ, Abrahão J, Ramos CH. Disaggregases, molecular chaperones that resolubilize protein aggregates. ACTA ACUST UNITED AC 2015; 87:1273-92. [DOI: 10.1590/0001-3765201520140671] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The process of folding is a seminal event in the life of a protein, as it is essential for proper protein function and therefore cell physiology. Inappropriate folding, or misfolding, can not only lead to loss of function, but also to the formation of protein aggregates, an insoluble association of polypeptides that harm cell physiology, either by themselves or in the process of formation. Several biological processes have evolved to prevent and eliminate the existence of non-functional and amyloidogenic aggregates, as they are associated with several human pathologies. Molecular chaperones and heat shock proteins are specialized in controlling the quality of the proteins in the cell, specifically by aiding proper folding, and dissolution and clearance of already formed protein aggregates. The latter is a function of disaggregases, mainly represented by the ClpB/Hsp104 subfamily of molecular chaperones, that are ubiquitous in all organisms but, surprisingly, have no orthologs in the cytosol of metazoan cells. This review aims to describe the characteristics of disaggregases and to discuss the function of yeast Hsp104, a disaggregase that is also involved in prion propagation and inheritance.
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Affiliation(s)
| | - Josielle Abrahão
- Universidade Estadual de Campinas, Brazil; Universidade Estadual de Campinas, Brazil
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18
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Abstract
Cellular homeostasis and stress survival requires maintenance of the proteome and suppression of proteotoxicity. Molecular chaperones promote cell survival through repair of misfolded proteins and cooperation with protein degradation machines to discard terminally damaged proteins. Hsp70 family members play an essential role in cellular protein metabolism by binding and releasing nonnative proteins to facilitate protein folding, refolding and degradation. Hsp40 family members are Hsp70 co-chaperones that determine the fate of Hsp70 clients by facilitating protein folding, assembly, and degradation. Hsp40s select substrates for Hsp70 via use of an intrinsic chaperone activity to bind non-native regions of proteins. During delivery of bound cargo Hsp40s employ a conserved J-domain to stimulate Hsp70 ATPase activity and thereby stabilize complexes between Hsp70 and non-native proteins. Type I and Type II Hsp40s direct Hsp70 to preform multiple functions in protein homeostasis. This review describes the mechanisms by which Type I and Type II sub-types of Hsp40 bind and deliver substrates to Hsp70.
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Affiliation(s)
- Douglas M Cyr
- Department of Cell Biology and Physiology, School of Medicine, University of North Carolina, 27599, Chapel Hill, NC, USA,
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19
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Overexpression of Q-rich prion-like proteins suppresses polyQ cytotoxicity and alters the polyQ interactome. Proc Natl Acad Sci U S A 2014; 111:18219-24. [PMID: 25489109 DOI: 10.1073/pnas.1421313111] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Expansion of a poly-glutamine (polyQ) repeat in a group of functionally unrelated proteins is the cause of several inherited neurodegenerative disorders, including Huntington's disease. The polyQ length-dependent aggregation and toxicity of these disease proteins can be reproduced in Saccharomyces cerevisiae. This system allowed us to screen for genes that when overexpressed reduce the toxic effects of an N-terminal fragment of mutant huntingtin with 103 Q. Surprisingly, among the identified suppressors were three proteins with Q-rich, prion-like domains (PrDs): glycine threonine serine repeat protein (Gts1p), nuclear polyadenylated RNA-binding protein 3, and minichromosome maintenance protein 1. Overexpression of the PrD of Gts1p, containing an imperfect 28 residue glutamine-alanine repeat, was sufficient for suppression of toxicity. Association with this discontinuous polyQ domain did not prevent 103Q aggregation, but altered the physical properties of the aggregates, most likely early in the assembly pathway, as reflected in their increased SDS solubility. Molecular simulations suggested that Gts1p arrests the aggregation of polyQ molecules at the level of nonfibrillar species, acting as a cap that destabilizes intermediates on path to form large fibrils. Quantitative proteomic analysis of polyQ interactors showed that expression of Gts1p reduced the interaction between polyQ and other prion-like proteins, and enhanced the association of molecular chaperones with the aggregates. These findings demonstrate that short, Q-rich peptides are able to shield the interactive surfaces of toxic forms of polyQ proteins and direct them into nontoxic aggregates.
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20
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Prion-like proteins sequester and suppress the toxicity of huntingtin exon 1. Proc Natl Acad Sci U S A 2014; 111:12085-90. [PMID: 25092318 DOI: 10.1073/pnas.1412504111] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Expansions of preexisting polyglutamine (polyQ) tracts in at least nine different proteins cause devastating neurodegenerative diseases. There are many unique features to these pathologies, but there must also be unifying mechanisms underlying polyQ toxicity. Using a polyQ-expanded fragment of huntingtin exon-1 (Htt103Q), the causal protein in Huntington disease, we and others have created tractable models for investigating polyQ toxicity in yeast cells. These models recapitulate key pathological features of human diseases and provide access to an unrivalled genetic toolbox. To identify toxicity modifiers, we performed an unbiased overexpression screen of virtually every protein encoded by the yeast genome. Surprisingly, there was no overlap between our modifiers and those from a conceptually identical screen reported recently, a discrepancy we attribute to an artifact of their overexpression plasmid. The suppressors of Htt103Q toxicity recovered in our screen were strongly enriched for glutamine- and asparagine-rich prion-like proteins. Separated from the rest of the protein, the prion-like sequences of these proteins were themselves potent suppressors of polyQ-expanded huntingtin exon-1 toxicity, in both yeast and human cells. Replacing the glutamines in these sequences with asparagines abolished suppression and converted them to enhancers of toxicity. Replacing asparagines with glutamines created stronger suppressors. The suppressors (but not the enhancers) coaggregated with Htt103Q, forming large foci at the insoluble protein deposit in which proteins were highly immobile. Cells possessing foci had fewer (if any) small diffusible oligomers of Htt103Q. Until such foci were lost, cells were protected from death. We discuss the therapeutic implications of these findings.
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