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Alonso P, Blas J, Amaro F, de Francisco P, Martín-González A, Gutiérrez JC. Cellular Response of Adapted and Non-Adapted Tetrahymena thermophila Strains to Europium Eu(III) Compounds. BIOLOGY 2024; 13:285. [PMID: 38785768 PMCID: PMC11117543 DOI: 10.3390/biology13050285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 04/17/2024] [Accepted: 04/21/2024] [Indexed: 05/25/2024]
Abstract
Europium is one of the most reactive lanthanides and humans use it in many different applications, but we still know little about its potential toxicity and cellular response to its exposure. Two strains of the eukaryotic microorganism model Tetrahymena thermophila were adapted to high concentrations of two Eu(III) compounds (EuCl3 or Eu2O3) and compared to a control strain and cultures treated with both compounds. In this ciliate, EuCl3 is more toxic than Eu2O3. LC50 values show that this microorganism is more resistant to these Eu(III) compounds than other microorganisms. Oxidative stress originated mainly by Eu2O3 is minimized by overexpression of genes encoding important antioxidant enzymes. The overexpression of metallothionein genes under treatment with Eu(III) compounds supports the possibility that this lanthanide may interact with the -SH groups of the cysteine residues from metallothioneins and/or displace essential cations of these proteins during their homeostatic function. Both lipid metabolism (lipid droplets fusing with europium-containing vacuoles) and autophagy are involved in the cellular response to europium stress. Bioaccumulation, together with a possible biomineralization to europium phosphate, seems to be the main mechanism of Eu(III) detoxification in these cells.
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Affiliation(s)
| | | | | | | | | | - Juan Carlos Gutiérrez
- Department of Genetics, Physiology and Microbiology, Faculty of Biology, Complutense University of Madrid, 28040 Madrid, Spain; (P.A.); (J.B.); (F.A.); (P.d.F.); (A.M.-G.)
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2
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Inactive Proteasomes Routed to Autophagic Turnover Are Confined within the Soluble Fraction of the Cell. Biomolecules 2022; 13:biom13010077. [PMID: 36671462 PMCID: PMC9855985 DOI: 10.3390/biom13010077] [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: 11/27/2022] [Revised: 12/22/2022] [Accepted: 12/27/2022] [Indexed: 01/01/2023] Open
Abstract
Previous studies demonstrated that dysfunctional yeast proteasomes accumulate in the insoluble protein deposit (IPOD), described as the final deposition site for amyloidogenic insoluble proteins and that this compartment also mediates proteasome ubiquitination, a prerequisite for their targeted autophagy (proteaphagy). Here, we examined the solubility state of proteasomes subjected to autophagy as a result of their inactivation, or under nutrient starvation. In both cases, only soluble proteasomes could serve as a substrate to autophagy, suggesting a modified model whereby substrates for proteaphagy are dysfunctional proteasomes in their near-native soluble state, and not as previously believed, those sequestered at the IPOD. Furthermore, the insoluble fraction accumulating in the IPOD represents an alternative pathway, enabling the removal of inactive proteasomes that escaped proteaphagy when the system became saturated. Altogether, we suggest that the relocalization of proteasomes to soluble aggregates represents a general stage of proteasome recycling through autophagy.
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3
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Son B, Yoon H, Ryu J, Lee H, Joo J, Park HH, Park TH. Enhanced efficiency of generating human-induced pluripotent stem cells using Lin28-30Kc19 fusion protein. Front Bioeng Biotechnol 2022; 10:911614. [PMID: 35935494 PMCID: PMC9354855 DOI: 10.3389/fbioe.2022.911614] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Accepted: 06/28/2022] [Indexed: 11/13/2022] Open
Abstract
Induced pluripotent stem cells (iPSCs) have intrinsic properties, such as self-renewal ability and pluripotency, which are also shown in embryonic stem cells (ESCs). The challenge of improving the iPSC generation efficiency has been an important issue and there have been many attempts to develop iPSC generation methods. In this research, we added Lin28, known as one of the reprogramming factors, in the form of a soluble recombinant protein from E. coli to improve the efficiency of human iPSC (hiPSC) generation, in respect of alkaline phosphatase (AP)-positive colonies. To deliver Lin28 inside the cells, we generated a soluble Lin28-30Kc19 fusion protein, with 30Kc19 at the C-terminal domain of Lin28. 30Kc19, a silkworm hemolymph-derived protein, was fused due to its cell-penetrating and protein-stabilizing properties. The Lin28-30Kc19 was treated to human dermal fibroblasts (HDFs), in combination with four defined reprogramming factors (Oct4, Sox2, c-Myc, and Klf4). After 14 days of cell culture, we confirmed the generated hiPSCs through AP staining. According to the results, the addition of Lin28-30Kc19 increased the number and size of generated AP-positive hiPSC colonies. Through this research, we anticipate that this recombinant protein would be a valuable material for increasing the efficiency of hiPSC generation and for enhancing the possibility as a substitute of the conventional method.
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Affiliation(s)
- Boram Son
- Department of Bioengineering, Hanyang University, Seoul, South Korea
| | - Hyungro Yoon
- Interdisciplinary Program in Bioengineering, Seoul National University, Seoul, South Korea
| | - Jina Ryu
- Interdisciplinary Program in Bioengineering, Seoul National University, Seoul, South Korea
| | - Haein Lee
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul, South Korea
| | - Jinmyoung Joo
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, South Korea
| | - Hee Ho Park
- Department of Bioengineering, Hanyang University, Seoul, South Korea
- Education and Research Group for Biopharmaceutical Innovation Leader, Hanyang University, Seoul, South Korea
- *Correspondence: Hee Ho Park, ; Tai Hyun Park,
| | - Tai Hyun Park
- Interdisciplinary Program in Bioengineering, Seoul National University, Seoul, South Korea
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul, South Korea
- BioMAX/N-Bio Institute, Institute of Bioengineering, Seoul National University, Seoul, South Korea
- *Correspondence: Hee Ho Park, ; Tai Hyun Park,
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4
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Sirati N, Popova B, Molenaar MR, Verhoek IC, Braus GH, Kaloyanova DV, Helms JB. Dynamic and Reversible Aggregation of the Human CAP Superfamily Member GAPR-1 in Protein Inclusions in Saccharomyces cerevisiae. J Mol Biol 2021; 433:167162. [PMID: 34298062 DOI: 10.1016/j.jmb.2021.167162] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 07/09/2021] [Accepted: 07/12/2021] [Indexed: 12/14/2022]
Abstract
Many proteins that can assemble into higher order structures termed amyloids can also concentrate into cytoplasmic inclusions via liquid-liquid phase separation. Here, we study the assembly of human Golgi-Associated plant Pathogenesis Related protein 1 (GAPR-1), an amyloidogenic protein of the Cysteine-rich secretory proteins, Antigen 5, and Pathogenesis-related 1 proteins (CAP) protein superfamily, into cytosolic inclusions in Saccharomyces cerevisiae. Overexpression of GAPR-1-GFP results in the formation GAPR-1 oligomers and fluorescent inclusions in yeast cytosol. These cytosolic inclusions are dynamic and reversible organelles that gradually increase during time of overexpression and decrease after promoter shut-off. Inclusion formation is, however, a regulated process that is influenced by factors other than protein expression levels. We identified N-myristoylation of GAPR-1 as an important determinant at early stages of inclusion formation. In addition, mutations in the conserved metal-binding site (His54 and His103) enhanced inclusion formation, suggesting that these residues prevent uncontrolled protein sequestration. In agreement with this, we find that addition of Zn2+ metal ions enhances inclusion formation. Furthermore, Zn2+ reduces GAPR-1 protein degradation, which indicates stabilization of GAPR-1 in inclusions. We propose that the properties underlying both the amyloidogenic properties and the reversible sequestration of GAPR-1 into inclusions play a role in the biological function of GAPR-1 and other CAP family members.
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Affiliation(s)
- Nafiseh Sirati
- Division of Cell Biology, Metabolism and Cancer, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands.
| | - Blagovesta Popova
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Institute for Microbiology and Genetics, Universität Göttingen, Göttingen, Germany
| | - Martijn R Molenaar
- Division of Cell Biology, Metabolism and Cancer, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
| | - Iris C Verhoek
- Division of Cell Biology, Metabolism and Cancer, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
| | - Gerhard H Braus
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Institute for Microbiology and Genetics, Universität Göttingen, Göttingen, Germany
| | - Dora V Kaloyanova
- Division of Cell Biology, Metabolism and Cancer, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
| | - J Bernd Helms
- Division of Cell Biology, Metabolism and Cancer, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands.
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Amen T, Kaganovich D. Small Molecule Screen Reveals Joint Regulation of Stress Granule Formation and Lipid Droplet Biogenesis. Front Cell Dev Biol 2021; 8:606111. [PMID: 33972926 PMCID: PMC8105174 DOI: 10.3389/fcell.2020.606111] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 12/21/2020] [Indexed: 01/22/2023] Open
Abstract
Metabolic regulation is a necessary component of all stress response pathways, because all different mechanisms of stress-adaptation place high-energy demands on the cell. Mechanisms that integrate diverse stress response pathways with their metabolic components are therefore of great interest, but few are known. We show that stress granule (SG) formation, a common adaptive response to a variety of stresses, is reciprocally regulated by the pathways inducing lipid droplet accumulation. Inability to upregulate lipid droplets reduces stress granule formation. Stress granule formation in turn drives lipid droplet clustering and fatty acid accumulation. Our findings reveal a novel connection between stress response pathways and new modifiers of stress granule formation.
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Affiliation(s)
- Triana Amen
- Department of Experimental Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
| | - Daniel Kaganovich
- Department of Experimental Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany.,1Base Pharmaceuticals, Boston, MA, United States
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6
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Abstract
Vimentin is one of the first cytoplasmic intermediate filaments to be expressed in mammalian cells during embryogenesis, but its role in cellular fitness has long been a mystery. Vimentin is acknowledged to play a role in cell stiffness, cell motility, and cytoplasmic organization, yet it is widely considered to be dispensable for cellular function and organismal development. Here, we show that Vimentin plays a role in cellular stress response in differentiating cells, by recruiting aggregates, stress granules, and RNA-binding proteins, directing their elimination and asymmetric partitioning. In the absence of Vimentin, pluripotent embryonic stem cells fail to differentiate properly, with a pronounced deficiency in neuronal differentiation. Our results uncover a novel function for Vimentin, with important implications for development, tissue homeostasis, and in particular, stress response.
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Fasnall Induces Atypically Transient Stress Granules Independently of FASN Inhibition. iScience 2020; 23:101550. [PMID: 33083719 PMCID: PMC7516299 DOI: 10.1016/j.isci.2020.101550] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 08/23/2020] [Accepted: 09/04/2020] [Indexed: 12/31/2022] Open
Abstract
Stress Granule formation has been linked to the resistance of some cancer cells to chemotherapeutic intervention. A number of studies have proposed that certain anti-tumor compounds promote cancer cell survival by inducing Stress Granule formation, leading to increased cellular fitness and apoptosis avoidance. Here we show that a potent fatty acid synthase inhibitor, fasnall, known for its anti-tumor capabilities, triggers the formation of atypical Stress Granules, independently of fatty acid synthase inhibition, characterized by high internal mobility and rapid turnover.
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Siwach P, Levy E, Livshits L, Feldman Y, Kaganovich D. Water is a biomarker of changes in the cellular environment in live animals. Sci Rep 2020; 10:9095. [PMID: 32499602 PMCID: PMC7272622 DOI: 10.1038/s41598-020-66022-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 05/12/2020] [Indexed: 11/09/2022] Open
Abstract
The biological processes that are associated with the physiological fitness state of a cell comprise a diverse set of molecular events. Reactive oxygen species (ROS), mitochondrial dysfunction, telomere shortening, genomic instability, epigenetic changes, protein aggregation, and down-regulation of quality control mechanisms are all hallmarks of cellular decline. Stress-related and decline-related changes can be assayed, but usually through means that are highly disruptive to living cells and tissues. Biomarkers for organismal decline and aging are urgently needed for diagnostic and drug development. Our goal in this study is to provide a proof-of-concept for a non-invasive assay of global molecular events in the cytoplasm of living animals. We show that Microwave Dielectric Spectroscopy (MDS) can be used to determine the hydration state of the intracellular environment in live C. elegans worms. MDS spectra were correlative with altered states in the cellular protein folding environment known to be associated with previously described mutations in the C. elegans lifespan and stress-response pathways.
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Affiliation(s)
- Pratibha Siwach
- Department of Experimental Neurodegeneration, University Medical Center Göttingen, Walweg 33, 37073, Göttingen, Germany
| | - Evgeniya Levy
- Department of Applied Physics, The Hebrew University of Jerusalem, Edmond J Safra campus, 919041, Jerusalem, Israel
| | - Leonid Livshits
- Vetsuisse Faculty, Institute of Veterinary Physiology, University of Zurich, Winterthurerstrasse 260, CH-8057, Zurich, Switzerland
| | - Yuri Feldman
- Department of Applied Physics, The Hebrew University of Jerusalem, Edmond J Safra campus, 919041, Jerusalem, Israel
| | - Daniel Kaganovich
- Department of Experimental Neurodegeneration, University Medical Center Göttingen, Walweg 33, 37073, Göttingen, Germany.
- 1Base Pharmaceuticals, Boston, MA, 02129, USA.
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Amen T, Kaganovich D. Stress granules sense metabolic stress at the plasma membrane and potentiate recovery by storing active Pkc1. Sci Signal 2020; 13:13/623/eaaz6339. [DOI: 10.1126/scisignal.aaz6339] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
As the physical barrier between the cell and the outside environment, the plasma membrane is well-positioned to be the first responder to stress. The membrane is also highly vulnerable to many types of perturbation, including heat, force, osmotic pressure, lipid shortage, and starvation. To determine whether the structural changes in the plasma membrane of Saccharomyces cerevisiae brought about by nutrient stress can be communicated to regulatory networks within the cell, we identified proteins that interact with stress granules (SGs), subcellular structures composed of proteins, and nontranslated RNAs that form when cells are stressed. We found that SG proteins interacted with components of eisosomes, which are subcortical membrane structures with a distinct lipid and protein composition. In response to starvation-triggered phosphorylation of eisosome proteins, eisosomes clustered and recruited SG components, including active Pkc1. The absence of eisosomes impaired SG formation, resulting in delayed recovery from nutrient deprivation. Thus, eisosome clustering is an example of interdomain communication in response to stress and identifies a previously unknown mechanism of SG regulation.
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Affiliation(s)
- Triana Amen
- Department of Experimental Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
| | - Daniel Kaganovich
- Department of Experimental Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
- 1Base Pharmaceuticals, Boston, MA 02129, USA
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10
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Chen C, Ding X, Akram N, Xue S, Luo SZ. Fused in Sarcoma: Properties, Self-Assembly and Correlation with Neurodegenerative Diseases. Molecules 2019; 24:molecules24081622. [PMID: 31022909 PMCID: PMC6514960 DOI: 10.3390/molecules24081622] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 04/12/2019] [Accepted: 04/17/2019] [Indexed: 12/13/2022] Open
Abstract
Fused in sarcoma (FUS) is a DNA/RNA binding protein that is involved in RNA metabolism and DNA repair. Numerous reports have demonstrated by pathological and genetic analysis that FUS is associated with a variety of neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), frontotemporal lobar degeneration (FTLD), and polyglutamine diseases. Traditionally, the fibrillar aggregation of FUS was considered to be the cause of those diseases, especially via its prion-like domains (PrLDs), which are rich in glutamine and asparagine residues. Lately, a nonfibrillar self-assembling phenomenon, liquid–liquid phase separation (LLPS), was observed in FUS, and studies of its functions, mechanism, and mutual transformation with pathogenic amyloid have been emerging. This review summarizes recent studies on FUS self-assembling, including both aggregation and LLPS as well as their relationship with the pathology of ALS, FTLD, and other neurodegenerative diseases.
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Affiliation(s)
- Chen Chen
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
| | - Xiufang Ding
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
| | - Nimrah Akram
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
| | - Song Xue
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
| | - Shi-Zhong Luo
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
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11
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Marsland R, England JL. Active regeneration unites high- and low-temperature features in cooperative self-assembly. Phys Rev E 2019; 98:022411. [PMID: 30253561 DOI: 10.1103/physreve.98.022411] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Indexed: 12/29/2022]
Abstract
Cytoskeletal filaments are capable of self-assembly in the absence of externally supplied chemical energy, but the rapid turnover rates essential for their biological function require a constant flux of adenosine triphosphate (ATP) or guanosine triphosphate (GTP) hydrolysis. The same is true for two-dimensional protein assemblies employed in the formation of vesicles from cellular membranes, which rely on ATP-hydrolyzing enzymes to rapidly disassemble upon completion of the process. Recent observations suggest that the nucleolus, p granules, and other three-dimensional membraneless organelles may also demand dissipation of chemical energy to maintain their fluidity. Cooperative binding plays a crucial role in the dynamics of these higher-dimensional structures, but is absent from classic models of one-dimensional cytoskeletal assembly. In this paper, we present a thermodynamically consistent model of active regeneration with cooperative assembly, and compute the maximum turnover rate and minimum disassembly time as a function of the chemical driving force and the binding energy. We find that these driven structures resemble different equilibrium states above and below the nucleation barrier. In particular, we show that the maximal acceleration under large binding energies unites infinite-temperature local fluctuations with low-temperature nucleation kinetics.
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Affiliation(s)
- Robert Marsland
- Physics of Living Systems Group, Department of Physics, Massachusetts Institute of Technology, 400 Technology Square, Cambridge, Massachusetts 02139, USA
| | - Jeremy L England
- Physics of Living Systems Group, Department of Physics, Massachusetts Institute of Technology, 400 Technology Square, Cambridge, Massachusetts 02139, USA
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12
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High-Reynolds Microfluidic Sorting of Large Yeast Populations. Sci Rep 2018; 8:13739. [PMID: 30214051 PMCID: PMC6137188 DOI: 10.1038/s41598-018-31726-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 08/02/2018] [Indexed: 12/24/2022] Open
Abstract
Microfluidic sorting offers a unique ability to isolate large numbers of cells for bulk proteomic or metabolomics studies but is currently limited by low throughput and persistent clogging at low flow rates. Recently we uncovered the physical principles governing the inertial focusing of particles in high-Reynolds numbers. Here, we superimpose high Reynolds inertial focusing on Dean vortices, to rapidly isolate large quantities of young and adult yeast from mixed populations at a rate of 107 cells/min/channel. Using a new algorithm to rapidly quantify budding scars in isolated yeast populations and system-wide proteomic analysis, we demonstrate that protein quality control and expression of established yeast aging markers such as CalM, RPL5, and SAM1 may change after the very first replication events, rather than later in the aging process as previously thought. Our technique enables the large-scale isolation of microorganisms based on minute differences in size (±1.5 μm), a feat unmatched by other technologies.
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13
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Rothe S, Prakash A, Tyedmers J. The Insoluble Protein Deposit (IPOD) in Yeast. Front Mol Neurosci 2018; 11:237. [PMID: 30050408 PMCID: PMC6052365 DOI: 10.3389/fnmol.2018.00237] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 06/18/2018] [Indexed: 11/13/2022] Open
Abstract
The appearance of protein aggregates is a hallmark of several pathologies including many neurodegenerative diseases. Mounting evidence suggests that the accumulation of misfolded proteins into inclusions is a secondary line of defense when the extent of protein misfolding exceeds the capacity of the Protein Quality Control System, which mediates refolding or degradation of misfolded species. Such exhaustion can occur during severe proteotoxic stress, the excessive occurrence of aggregation prone protein species, e.g., amyloids, or during ageing. However, the machinery that mediates recognition, recruitment and deposition of different types of misfolded proteins into specific deposition sites is only poorly understood. Since emerging principles of aggregate deposition appear evolutionarily conserved, yeast represents a powerful model to study basic mechanisms of recognition of different types of misfolded proteins, their recruitment to the respective deposition site and the molecular organization at the corresponding site. Yeast possesses at least three different aggregate deposition sites, one of which is a major deposition site for amyloid aggregates termed Insoluble PrOtein Deposit (IPOD). Due to the link between neurodegenerative disease and accumulation of amyloid aggregates, the IPOD is of particular interest when we aim to identify the molecular mechanisms that cells have evolved to counteract toxicity associated with the occurrence of amyloid aggregates. Here, we will review what is known about IPOD composition and the mechanisms of recognition and recruitment of amyloid aggregates to this site in yeast. Finally, we will briefly discuss the possible physiological role of aggregate deposition at the IPOD.
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Affiliation(s)
- Stephanie Rothe
- Department of Medicine I and Clinical Chemistry, Heidelberg University Hospital, Heidelberg, Germany
| | - Abaya Prakash
- Department of Medicine I and Clinical Chemistry, Heidelberg University Hospital, Heidelberg, Germany
| | - Jens Tyedmers
- Department of Medicine I and Clinical Chemistry, Heidelberg University Hospital, Heidelberg, Germany
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14
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Alberti S, Carra S. Quality Control of Membraneless Organelles. J Mol Biol 2018; 430:4711-4729. [PMID: 29758260 DOI: 10.1016/j.jmb.2018.05.013] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 05/04/2018] [Accepted: 05/04/2018] [Indexed: 02/06/2023]
Abstract
The formation of membraneless organelles (MLOs) by phase separation has emerged as a new way of organizing the cytoplasm and nucleoplasm of cells. Examples of MLOs forming via phase separation are nucleoli in the nucleus and stress granules in the cytoplasm. The main components of these MLOs are macromolecules such as RNAs and proteins. In order to assemble by phase separation, these proteins and RNAs have to undergo many cooperative interactions. These cooperative interactions are supported by specific molecular features within phase-separating proteins, such as multivalency and the presence of disordered domains that promote weak and transient interactions. However, these features also predispose phase-separating proteins to aberrant behavior. Indeed, evidence is emerging for a strong link between phase-separating proteins, MLOs, and age-related diseases. In this review, we discuss recent progress in understanding the formation, properties, and functions of MLOs. We pay special attention to the emerging link between MLOs and age-related diseases, and we explain how changes in the composition and physical properties of MLOs promote their conversion into an aberrant state. Furthermore, we discuss the key role of the protein quality control machinery in regulating the properties and functions of MLOs and thus in preventing age-related diseases.
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Affiliation(s)
- Simon Alberti
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany.
| | - Serena Carra
- Department of Biomedical, Metabolic and Neural Science, University of Modena and Reggio Emilia, Center for Neuroscience and Neurotechnology, 41125 Modena, Italy.
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15
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Drozdova P, Lipaeva P, Rogoza T, Zhouravleva G, Bondarev S. Overproduction of Sch9 leads to its aggregation and cell elongation in Saccharomyces cerevisiae. PLoS One 2018; 13:e0193726. [PMID: 29494682 PMCID: PMC5832320 DOI: 10.1371/journal.pone.0193726] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 02/16/2018] [Indexed: 11/25/2022] Open
Abstract
The Sch9 kinase of Saccharomyces cerevisiae is one of the major TOR pathway effectors and regulates diverse processes in the cell. Sch9 belongs to the AGC kinase family. In human, amplification of AGC kinase genes is connected with cancer. However, not much is known about the effects of Sch9 overproduction in yeast cells. To fill this gap, we developed a model system to monitor subcellular location and aggregation state of overproduced Sch9 or its regions fused to a fluorescent protein. With this system, we showed that Sch9-YFP forms detergent-resistant aggregates, and multiple protein regions are responsible for this. This finding corroborated the fact that Sch9-YFP is visualized as various fluorescent foci. In addition, we found that Sch9 overproduction caused cell elongation, and this effect was determined by its C-terminal region containing kinase domains. The constructs we present can be exploited to create superior yeast-based model systems to study processes behind kinase overproduction in cancers.
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Affiliation(s)
- Polina Drozdova
- Dept. of Genetics and Biotechnology, Saint Petersburg State University, St. Petersburg, Russia
| | - Polina Lipaeva
- Dept. of Genetics and Biotechnology, Saint Petersburg State University, St. Petersburg, Russia
| | - Tatyana Rogoza
- Dept. of Genetics and Biotechnology, Saint Petersburg State University, St. Petersburg, Russia
- Vavilov Institute of General Genetics, St. Petersburg Branch, Russian Academy of Sciences, St. Petersburg, Russia
| | - Galina Zhouravleva
- Dept. of Genetics and Biotechnology, Saint Petersburg State University, St. Petersburg, Russia
- The Laboratory of Amyloid Biology, Saint Petersburg State University, St. Petersburg, Russia
| | - Stanislav Bondarev
- Dept. of Genetics and Biotechnology, Saint Petersburg State University, St. Petersburg, Russia
- The Laboratory of Amyloid Biology, Saint Petersburg State University, St. Petersburg, Russia
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16
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There Is an Inclusion for That: Material Properties of Protein Granules Provide a Platform for Building Diverse Cellular Functions. Trends Biochem Sci 2017; 42:765-776. [DOI: 10.1016/j.tibs.2017.08.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 07/26/2017] [Accepted: 08/03/2017] [Indexed: 12/30/2022]
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17
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Gu ZC, Wu E, Sailer C, Jando J, Styles E, Eisenkolb I, Kuschel M, Bitschar K, Wang X, Huang L, Vissa A, Yip CM, Yedidi RS, Friesen H, Enenkel C. Ubiquitin orchestrates proteasome dynamics between proliferation and quiescence in yeast. Mol Biol Cell 2017; 28:2479-2491. [PMID: 28768827 PMCID: PMC5597321 DOI: 10.1091/mbc.e17-03-0162] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 06/16/2017] [Accepted: 07/24/2017] [Indexed: 12/14/2022] Open
Abstract
Proteasomes are key protease complexes responsible for protein degradation, and their localization changes with the growth conditions. This work in yeast shows that proteasomes exit the nucleus with the transition from proliferation to quiescence. Ubiquitin is a key player in proteasome dynamics and cytoplasmic proteasome granule formation. Proteasomes are essential for protein degradation in proliferating cells. Little is known about proteasome functions in quiescent cells. In nondividing yeast, a eukaryotic model of quiescence, proteasomes are depleted from the nucleus and accumulate in motile cytosolic granules termed proteasome storage granules (PSGs). PSGs enhance resistance to genotoxic stress and confer fitness during aging. Upon exit from quiescence PSGs dissolve, and proteasomes are rapidly delivered into the nucleus. To identify key players in PSG organization, we performed high-throughput imaging of green fluorescent protein (GFP)-labeled proteasomes in the yeast null-mutant collection. Mutants with reduced levels of ubiquitin are impaired in PSG formation. Colocalization studies of PSGs with proteins of the yeast GFP collection, mass spectrometry, and direct stochastic optical reconstitution microscopy of cross-linked PSGs revealed that PSGs are densely packed with proteasomes and contain ubiquitin but no polyubiquitin chains. Our results provide insight into proteasome dynamics between proliferating and quiescent yeast in response to cellular requirements for ubiquitin-dependent degradation.
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Affiliation(s)
- Zhu Chao Gu
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Edwin Wu
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Carolin Sailer
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Julia Jando
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Erin Styles
- Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Ina Eisenkolb
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Maike Kuschel
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Katharina Bitschar
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Xiaorong Wang
- Department of Physics and Biophysics, University of California, Irvine, Irvine, CA 92697
| | - Lan Huang
- Department of Physics and Biophysics, University of California, Irvine, Irvine, CA 92697
| | - Adriano Vissa
- Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Christopher M Yip
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada.,Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Ravikiran S Yedidi
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Helena Friesen
- Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Cordula Enenkel
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada
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18
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Welte MA, Gould AP. Lipid droplet functions beyond energy storage. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1862:1260-1272. [PMID: 28735096 PMCID: PMC5595650 DOI: 10.1016/j.bbalip.2017.07.006] [Citation(s) in RCA: 331] [Impact Index Per Article: 47.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 07/17/2017] [Accepted: 07/17/2017] [Indexed: 02/07/2023]
Abstract
Lipid droplets are cytoplasmic organelles that store neutral lipids and are critically important for energy metabolism. Their function in energy storage is firmly established and increasingly well characterized. However, emerging evidence indicates that lipid droplets also play important and diverse roles in the cellular handling of lipids and proteins that may not be directly related to energy homeostasis. Lipid handling roles of droplets include the storage of hydrophobic vitamin and signaling precursors, and the management of endoplasmic reticulum and oxidative stress. Roles of lipid droplets in protein handling encompass functions in the maturation, storage, and turnover of cellular and viral polypeptides. Other potential roles of lipid droplets may be connected with their intracellular motility and, in some cases, their nuclear localization. This diversity highlights that lipid droplets are very adaptable organelles, performing different functions in different biological contexts. This article is part of a Special Issue entitled: Recent Advances in Lipid Droplet Biology edited by Rosalind Coleman and Matthijs Hesselink.
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Affiliation(s)
- Michael A Welte
- Department of Biology, University of Rochester, Rochester, NY, United States.
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19
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Abstract
Replicative aging has been demonstrated in asymmetrically dividing unicellular organisms, seemingly caused by unequal damage partitioning. Although asymmetric segregation and inheritance of potential aging factors also occur in symmetrically dividing species, it nevertheless remains controversial whether this results in aging. Based on large-scale single-cell lineage data obtained by time-lapse microscopy with a microfluidic device, in this report, we demonstrate the absence of replicative aging in old-pole cell lineages of Schizosaccharomyces pombe cultured under constant favorable conditions. By monitoring more than 1,500 cell lineages in 7 different culture conditions, we showed that both cell division and death rates are remarkably constant for at least 50–80 generations. Our measurements revealed that the death rate per cellular generation increases with the division rate, pointing to a physiological trade-off with fast growth under balanced growth conditions. We also observed the formation and inheritance of Hsp104-associated protein aggregates, which are a potential aging factor in old-pole cell lineages, and found that these aggregates exhibited a tendency to preferentially remain at the old poles for several generations. However, the aggregates were eventually segregated from old-pole cells upon cell division and probabilistically allocated to new-pole cells. We found that cell deaths were typically preceded by sudden acceleration of protein aggregation; thus, a relatively large amount of protein aggregates existed at the very ends of the dead cell lineages. Our lineage tracking analyses, however, revealed that the quantity and inheritance of protein aggregates increased neither cellular generation time nor cell death initiation rates. Furthermore, our results demonstrated that unusually large amounts of protein aggregates induced by oxidative stress exposure did not result in aging; old-pole cells resumed normal growth upon stress removal, despite the fact that most of them inherited significant quantities of aggregates. These results collectively indicate that protein aggregates are not a major determinant of triggering cell death in S. pombe and thus cannot be an appropriate molecular marker or index for replicative aging under both favorable and stressful environmental conditions. Multicellular organisms universally senesce and must produce rejuvenated progenies in order to transmit life. Although similar age-related deterioration in physiological functions and reproduction is also found in unicellular organisms that divide asymmetrically to produce morphologically distinct aged and younger cells, it has been unclear whether symmetrically dividing microbes—such as fission yeast—exhibit the same traits. Using long-term live-cell microscopy combined with a microfluidic device, we monitor the growth and death of a large number of fission yeast cells and demonstrate the existence of aging-free lineages. These lineages are, however, not immortal, and the probability of death increases as the cells grow more rapidly; thus, the “live fast, die fast” trade-off exists in fission yeast. We further characterize the segregation and inheritance of protein aggregates, which are commonly thought of as “aging factors.” The aging-free lineages bear the aggregate load for some generations with no apparent adverse effects on growth. We also show that there is no threshold amount of protein aggregate above which cells are destined to death in both normal and stressed conditions: protein aggregate is thus not a direct initiation signal for cell death. Our data reveal that protein aggregation might not be an appropriate index for aging and that we should revisit its role in cell physiology.
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Affiliation(s)
- Hidenori Nakaoka
- Department of Basic Science, Graduate School of Arts and Sciences, University of Tokyo, Komaba, Meguro-ku, Tokyo, Japan
| | - Yuichi Wakamoto
- Department of Basic Science, Graduate School of Arts and Sciences, University of Tokyo, Komaba, Meguro-ku, Tokyo, Japan
- Research Center for Complex Systems Biology, University of Tokyo, Komaba, Meguro-ku, Tokyo, Japan
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20
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Mitotic Dysfunction Associated with Aging Hallmarks. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1002:153-188. [DOI: 10.1007/978-3-319-57127-0_7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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21
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Rinas U, Garcia-Fruitós E, Corchero JL, Vázquez E, Seras-Franzoso J, Villaverde A. Bacterial Inclusion Bodies: Discovering Their Better Half. Trends Biochem Sci 2017; 42:726-737. [PMID: 28254353 DOI: 10.1016/j.tibs.2017.01.005] [Citation(s) in RCA: 109] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 01/23/2017] [Accepted: 01/26/2017] [Indexed: 01/07/2023]
Abstract
Bacterial inclusion bodies (IBs) are functional, non-toxic amyloids occurring in recombinant bacteria showing analogies with secretory granules of the mammalian endocrine system. The scientific interest in these mesoscale protein aggregates has been historically masked by their status as a hurdle in recombinant protein production. However, progressive understanding of how the cell handles the quality of recombinant polypeptides and the main features of their intriguing molecular organization has stimulated the interest in inclusion bodies and spurred their use in diverse technological fields. The engineering and tailoring of IBs as functional protein particles for materials science and biomedicine is a good example of how formerly undesired bacterial byproducts can be rediscovered as promising functional materials for a broad spectrum of applications.
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Affiliation(s)
- Ursula Rinas
- Leibniz University of Hannover, Technical Chemistry and Life Science, Hannover, Germany; Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Elena Garcia-Fruitós
- Department of Ruminant Production, Institut de Recerca i Tecnologia Agroalimentàries (IRTA), Torre Marimon, 08140 Caldes de Montbui, Barcelona, Spain
| | - José Luis Corchero
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Bellaterra, 08193 Cerdanyola del Vallès, Spain; Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, Bellaterra, 08193 Cerdanyola del Vallès, Spain; Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Bellaterra, 08193 Cerdanyola del Vallès, Spain
| | - Esther Vázquez
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Bellaterra, 08193 Cerdanyola del Vallès, Spain; Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, Bellaterra, 08193 Cerdanyola del Vallès, Spain; Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Bellaterra, 08193 Cerdanyola del Vallès, Spain
| | - Joaquin Seras-Franzoso
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Bellaterra, 08193 Cerdanyola del Vallès, Spain; Molecular Biology and Biochemistry Research Center for Nanomedicine (Cibbim-Nanomedicine), Hospital Vall d'Hebron, Passeig de la Vall d'Hebron, 119-129, 08035 Barcelona, Spain
| | - Antonio Villaverde
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Bellaterra, 08193 Cerdanyola del Vallès, Spain; Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, Bellaterra, 08193 Cerdanyola del Vallès, Spain; Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Bellaterra, 08193 Cerdanyola del Vallès, Spain.
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22
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Liu WJ, Ye L, Huang WF, Guo LJ, Xu ZG, Wu HL, Yang C, Liu HF. p62 links the autophagy pathway and the ubiqutin-proteasome system upon ubiquitinated protein degradation. Cell Mol Biol Lett 2016; 21:29. [PMID: 28536631 PMCID: PMC5415757 DOI: 10.1186/s11658-016-0031-z] [Citation(s) in RCA: 572] [Impact Index Per Article: 71.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Accepted: 12/07/2016] [Indexed: 01/19/2023] Open
Abstract
The ubiquitin–proteasome system (UPS) and autophagy are two distinct and interacting proteolytic systems. They play critical roles in cell survival under normal conditions and during stress. An increasing body of evidence indicates that ubiquitinated cargoes are important markers of degradation. p62, a classical receptor of autophagy, is a multifunctional protein located throughout the cell and involved in many signal transduction pathways, including the Keap1–Nrf2 pathway. It is involved in the proteasomal degradation of ubiquitinated proteins. When the cellular p62 level is manipulated, the quantity and location pattern of ubiquitinated proteins change with a considerable impact on cell survival. Altered p62 levels can even lead to some diseases. The proteotoxic stress imposed by proteasome inhibition can activate autophagy through p62 phosphorylation. A deficiency in autophagy may compromise the ubiquitin–proteasome system, since overabundant p62 delays delivery of the proteasomal substrate to the proteasome despite proteasomal catalytic activity being unchanged. In addition, p62 and the proteasome can modulate the activity of HDAC6 deacetylase, thus influencing the autophagic degradation.
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Affiliation(s)
- Wei Jing Liu
- The Institute of Nephrology, Guangdong Medical University, Zhanjiang, Guangdong 524001 China.,Key Laboratory of Chinese Internal Medicine of Ministry of Education and Beijing, Dongzhimen Hospital Affiliated to Beijing University of Chinese Medicine, Beijing, 100700 China
| | - Lin Ye
- The Institute of Nephrology, Guangdong Medical University, Zhanjiang, Guangdong 524001 China
| | - Wei Fang Huang
- The Institute of Nephrology, Guangdong Medical University, Zhanjiang, Guangdong 524001 China
| | - Lin Jie Guo
- The Institute of Nephrology, Guangdong Medical University, Zhanjiang, Guangdong 524001 China
| | - Zi Gan Xu
- The Institute of Nephrology, Guangdong Medical University, Zhanjiang, Guangdong 524001 China
| | - Hong Luan Wu
- The Institute of Nephrology, Guangdong Medical University, Zhanjiang, Guangdong 524001 China
| | - Chen Yang
- The Institute of Nephrology, Guangdong Medical University, Zhanjiang, Guangdong 524001 China
| | - Hua Feng Liu
- The Institute of Nephrology, Guangdong Medical University, Zhanjiang, Guangdong 524001 China
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23
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Nevzglyadova OV, Artemov AV, Mikhailova EV, Lyublinskaya OG, Ozerova YE, Ivanova PA, Kostyleva EI, Soidla TR. The effect of yeast Saccharomyces cerevisiae red pigment on the expression of cloned human α-synuclein. ACTA ACUST UNITED AC 2016. [DOI: 10.1134/s1990519x16040106] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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24
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25
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Halfmann R. A glass menagerie of low complexity sequences. Curr Opin Struct Biol 2016; 38:18-25. [PMID: 27258703 DOI: 10.1016/j.sbi.2016.05.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 05/06/2016] [Accepted: 05/11/2016] [Indexed: 10/24/2022]
Abstract
Remarkably simple proteins play outsize roles in the execution of developmental complexity within biological systems. Sequence information determines structure and hence function, so how do low complexity sequences fulfill their functions? Recent discoveries are raising the curtain on a new dimension of the sequence-structure paradigm. In it, function derives not from the structures of individual proteins, but instead, from dynamic material properties of entire ensembles of the proteins acting in unison through phase changes. These phases include liquids, one-dimensional crystals, and - as elaborated herein - even glasses. The peculiar thermodynamics of glass-like protein assemblies, in particular, illuminate new principles of information flow through and, at times, orthogonal to the central dogma of molecular biology.
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Affiliation(s)
- Randal Halfmann
- Stowers Institute for Medical Research, 1000 E. 50th St., Kansas City, MO 64110, USA; Department of Molecular and Integrative Physiology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA.
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26
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Oeser ML, Amen T, Nadel CM, Bradley AI, Reed BJ, Jones RD, Gopalan J, Kaganovich D, Gardner RG. Dynamic Sumoylation of a Conserved Transcription Corepressor Prevents Persistent Inclusion Formation during Hyperosmotic Stress. PLoS Genet 2016; 12:e1005809. [PMID: 26800527 PMCID: PMC4723248 DOI: 10.1371/journal.pgen.1005809] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 12/22/2015] [Indexed: 11/29/2022] Open
Abstract
Cells are often exposed to physical or chemical stresses that can damage the structures of essential biomolecules. Stress-induced cellular damage can become deleterious if not managed appropriately. Rapid and adaptive responses to stresses are therefore crucial for cell survival. In eukaryotic cells, different stresses trigger post-translational modification of proteins with the small ubiquitin-like modifier SUMO. However, the specific regulatory roles of sumoylation in each stress response are not well understood. Here, we examined the sumoylation events that occur in budding yeast after exposure to hyperosmotic stress. We discovered by proteomic and biochemical analyses that hyperosmotic stress incurs the rapid and transient sumoylation of Cyc8 and Tup1, which together form a conserved transcription corepressor complex that regulates hundreds of genes. Gene expression and cell biological analyses revealed that sumoylation of each protein directs distinct outcomes. In particular, we discovered that Cyc8 sumoylation prevents the persistence of hyperosmotic stress-induced Cyc8-Tup1 inclusions, which involves a glutamine-rich prion domain in Cyc8. We propose that sumoylation protects against persistent inclusion formation during hyperosmotic stress, allowing optimal transcriptional function of the Cyc8-Tup1 complex. Cells have evolved complex stress responses to cope with environmental challenges that could otherwise inflict severe damage on the molecules essential for life. Stress responses must ameliorate the immediate damage caused by stress exposure and also adjust metabolic capacity, gene expression output, and other cellular functions to protect against further damage that could be incurred by prolonged exposure to stress. Posttranslational protein modifications are a major means by which cells respond to changing environmental conditions. These modifications can alter the function, localization, and molecular interactions of their target proteins. In addition, evidence is emerging that some posttranslational modifications may also change the physical characteristics of target proteins. In this study, we present evidence that during hyperosmotic stress, a condition known to induce protein misfolding, cells rapidly but transiently use the small ubiquitin-modifier SUMO to protect against persistent inclusion formation of a conserved transcriptional repressor complex. We propose that this rapid protective action via posttranslational modification enables optimal gene regulation during the cellular response to hyperosmotic stress.
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Affiliation(s)
- Michelle L. Oeser
- Molecular and Cellular Biology Program, University of Washington, Seattle, Washington, United States of America
- Department of Pharmacology, University of Washington, Seattle, Washington, United States of America
| | - Triana Amen
- Alexander Grass Center for Bioengineering, Hebrew University of Jerusalem, Jerusalem, Israel
- Department of Cell and Developmental Biology, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Cory M. Nadel
- Department of Pharmacology, University of Washington, Seattle, Washington, United States of America
| | - Amanda I. Bradley
- Molecular and Cellular Biology Program, University of Washington, Seattle, Washington, United States of America
| | - Benjamin J. Reed
- Department of Pharmacology, University of Washington, Seattle, Washington, United States of America
| | - Ramon D. Jones
- Department of Pharmacology, University of Washington, Seattle, Washington, United States of America
| | - Janani Gopalan
- Department of Pharmacology, University of Washington, Seattle, Washington, United States of America
| | - Daniel Kaganovich
- Department of Cell and Developmental Biology, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Richard G. Gardner
- Molecular and Cellular Biology Program, University of Washington, Seattle, Washington, United States of America
- Department of Pharmacology, University of Washington, Seattle, Washington, United States of America
- * E-mail:
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27
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Uchida T, Tamaki Y, Ayaki T, Shodai A, Kaji S, Morimura T, Banno Y, Nishitsuji K, Sakashita N, Maki T, Yamashita H, Ito H, Takahashi R, Urushitani M. CUL2-mediated clearance of misfolded TDP-43 is paradoxically affected by VHL in oligodendrocytes in ALS. Sci Rep 2016; 6:19118. [PMID: 26751167 PMCID: PMC4707540 DOI: 10.1038/srep19118] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 12/04/2015] [Indexed: 12/28/2022] Open
Abstract
The molecular machinery responsible for cytosolic accumulation of misfolded TDP-43 in amyotrophic lateral sclerosis (ALS) remains elusive. Here we identified a cullin-2 (CUL2) RING complex as a novel ubiquitin ligase for fragmented forms of TDP-43. The von Hippel Lindau protein (VHL), a substrate binding component of the complex, preferentially recognized misfolded TDP-43 at Glu246 in RNA-recognition motif 2. Recombinant full-length TDP-43 was structurally fragile and readily cleaved, suggesting that misfolded TDP-43 is cleared by VHL/CUL2 in a step-wise manner via fragmentation. Surprisingly, excess VHL stabilized and led to inclusion formation of TDP-43, as well as mutant SOD1, at the juxtanuclear protein quality control center. Moreover, TDP-43 knockdown elevated VHL expression in cultured cells, implying an aberrant interaction between VHL and mislocalized TDP-43 in ALS. Finally, cytoplasmic inclusions especially in oligodendrocytes in ALS spinal cords were immunoreactive to both phosphorylated TDP-43 and VHL. Thus, our results suggest that an imbalance in VHL and CUL2 may underlie oligodendrocyte dysfunction in ALS, and highlight CUL2 E3 ligase emerges as a novel therapeutic potential for ALS.
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Affiliation(s)
- Tsukasa Uchida
- Department of Neurology, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto, 606-8507 Japan
| | - Yoshitaka Tamaki
- Department of Neurology, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto, 606-8507 Japan
| | - Takashi Ayaki
- Department of Neurology, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto, 606-8507 Japan
| | - Akemi Shodai
- Department of Neurology, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto, 606-8507 Japan
| | - Seiji Kaji
- Department of Neurology, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto, 606-8507 Japan
| | - Toshifumi Morimura
- Molecular Neuroscience Research Center, Shiga University of Medical Science, Seta-Tsukinowa-cho, Otsu, Shiga 520-2192, Japan
| | - Yoshinori Banno
- Molecular Neuroscience Research Center, Shiga University of Medical Science, Seta-Tsukinowa-cho, Otsu, Shiga 520-2192, Japan
| | - Kazuchika Nishitsuji
- Department of Molecular Pathology, Tokushima University, 2-24 Shinkuracho, Tokushima, Tokushima Prefecture 770-0855, Japan
| | - Naomi Sakashita
- Department of Molecular Pathology, Tokushima University, 2-24 Shinkuracho, Tokushima, Tokushima Prefecture 770-0855, Japan
| | - Takakuni Maki
- Department of Neurology, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto, 606-8507 Japan
| | - Hirofumi Yamashita
- Department of Neurology, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto, 606-8507 Japan
| | - Hidefumi Ito
- Department of Neurology, Wakayama Medical University, 811-1 Kimiidera, Wakayama, Wakayama Prefecture 641-8509, Japan
| | - Ryosuke Takahashi
- Department of Neurology, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto, 606-8507 Japan
| | - Makoto Urushitani
- Department of Neurology, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto, 606-8507 Japan
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28
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Peters LZ, Karmon O, Miodownik S, Ben-Aroya S. Proteasome storage granules are transiently associated with the insoluble protein deposit (IPOD). J Cell Sci 2016; 129:1190-7. [DOI: 10.1242/jcs.179648] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 01/26/2016] [Indexed: 12/28/2022] Open
Abstract
Proteasome storage granules (PSGs) are created in yeast as part of an extensive, programmed reorganization of proteins into reversible assemblies, upon carbon source depletion. Here, we demonstrate that cells distinguish dysfunctional proteasomes from PSGs on the cytosolic insoluble protein deposit (IPOD). Furthermore, we provide evidence that this is a general mechanism for the reorganization of additional proteins into reversible assemblies. Our study expands the roles of the IPOD which may serve not only as the specific depository for amyloidogenic and misfolded proteins, but also as a potential hub, from which proteins are directed to distinct cellular compartments. These findings therefore provide a framework for understanding how cells discriminate between intact and abnormal proteins under stress conditions to ensure that only structurally ‘correct’ proteins are deployed.
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Affiliation(s)
- Lee Zeev Peters
- Faculty of Life Sciences Bar-Ilan University, Ramat-Gan, Israel
| | - Ofri Karmon
- Faculty of Life Sciences Bar-Ilan University, Ramat-Gan, Israel
| | - Shir Miodownik
- Faculty of Life Sciences Bar-Ilan University, Ramat-Gan, Israel
| | - Shay Ben-Aroya
- Faculty of Life Sciences Bar-Ilan University, Ramat-Gan, Israel
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29
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Amen T, Lázaro DF, Outeiro TF, Kaganovich D. Modeling Neuronal Pathology in Yeast: Insights into the Molecular Basis of Parkinson’s Disease. Isr J Chem 2015. [DOI: 10.1002/ijch.201500071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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30
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Brielle S, Gura R, Kaganovich D. Imaging stress. Cell Stress Chaperones 2015; 20:867-74. [PMID: 26139131 PMCID: PMC4595435 DOI: 10.1007/s12192-015-0615-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 06/16/2015] [Accepted: 06/17/2015] [Indexed: 10/23/2022] Open
Abstract
Recent innovations in cell biology and imaging approaches are changing the way we study cellular stress, protein misfolding, and aggregation. Studies have begun to show that stress responses are even more variegated and dynamic than previously thought, encompassing nano-scale reorganization of cytosolic machinery that occurs almost instantaneously, much faster than transcriptional responses. Moreover, protein and mRNA quality control is often organized into highly dynamic macromolecular assemblies, or dynamic droplets, which could easily be mistaken for dysfunctional "aggregates," but which are, in fact, regulated functional compartments. The nano-scale architecture of stress-response ranges from diffraction-limited structures like stress granules, P-bodies, and stress foci to slightly larger quality control inclusions like juxta nuclear quality control compartment (JUNQ) and insoluble protein deposit compartment (IPOD), as well as others. Examining the biochemical and physical properties of these dynamic structures necessitates live cell imaging at high spatial and temporal resolution, and techniques to make quantitative measurements with respect to movement, localization, and mobility. Hence, it is important to note some of the most recent observations, while casting an eye towards new imaging approaches that offer the possibility of collecting entirely new kinds of data from living cells.
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Affiliation(s)
- Shlomi Brielle
- Department of Cell and Developmental Biology, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, 91904, Israel
- Alexander Grass Center for Bioengineering, Hebrew University of Jerusalem, Jerusalem, Israel, 91904
| | - Rotem Gura
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Daniel Kaganovich
- Department of Cell and Developmental Biology, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, 91904, Israel.
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Castellano LM, Bart SM, Holmes VM, Weissman D, Shorter J. Repurposing Hsp104 to Antagonize Seminal Amyloid and Counter HIV Infection. ACTA ACUST UNITED AC 2015; 22:1074-86. [PMID: 26256479 DOI: 10.1016/j.chembiol.2015.07.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 06/30/2015] [Accepted: 07/07/2015] [Indexed: 11/30/2022]
Abstract
Naturally occurring proteolytic fragments of prostatic acid phosphatase (PAP248-286 and PAP85-120) and semenogelins (SEM1 and SEM2) form amyloid fibrils in seminal fluid, which capture HIV virions and promote infection. For example, PAP248-286 fibrils, termed SEVI (semen-derived enhancer of viral infection), can potentiate HIV infection by several orders of magnitude. Here, we design three disruptive technologies to rapidly antagonize seminal amyloid by repurposing Hsp104, an amyloid-remodeling nanomachine from yeast. First, Hsp104 and an enhanced engineered variant, Hsp104(A503V), directly remodel SEVI and PAP85-120 fibrils into non-amyloid forms. Second, we elucidate catalytically inactive Hsp104 scaffolds that do not remodel amyloid structure, but cluster SEVI, PAP85-120, and SEM1(45-107) fibrils into larger assemblies. Third, we modify Hsp104 to interact with the chambered protease ClpP, which enables coupled remodeling and degradation to irreversibly clear SEVI and PAP85-120 fibrils. Each strategy diminished the ability of seminal amyloid to promote HIV infection, and could have therapeutic utility.
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Affiliation(s)
- Laura M Castellano
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Pharmacology Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Stephen M Bart
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Cell and Molecular Biology Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Veronica M Holmes
- Division of Infectious Diseases, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Drew Weissman
- Division of Infectious Diseases, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - James Shorter
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Pharmacology Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Cell and Molecular Biology Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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32
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Finka A, Sood V, Quadroni M, Rios PDL, Goloubinoff P. Quantitative proteomics of heat-treated human cells show an across-the-board mild depletion of housekeeping proteins to massively accumulate few HSPs. Cell Stress Chaperones 2015; 20:605-20. [PMID: 25847399 PMCID: PMC4463922 DOI: 10.1007/s12192-015-0583-2] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Revised: 03/08/2015] [Accepted: 03/10/2015] [Indexed: 11/18/2022] Open
Abstract
Classic semiquantitative proteomic methods have shown that all organisms respond to a mild heat shock by an apparent massive accumulation of a small set of proteins, named heat-shock proteins (HSPs) and a concomitant slowing down in the synthesis of the other proteins. Yet unexplained, the increased levels of HSP messenger RNAs (mRNAs) may exceed 100 times the ensuing relative levels of HSP proteins. We used here high-throughput quantitative proteomics and targeted mRNA quantification to estimate in human cell cultures the mass and copy numbers of the most abundant proteins that become significantly accumulated, depleted, or unchanged during and following 4 h at 41 °C, which we define as mild heat shock. This treatment caused a minor across-the-board mass loss in many housekeeping proteins, which was matched by a mass gain in a few HSPs, predominantly cytosolic HSPCs (HSP90s) and HSPA8 (HSC70). As the mRNAs of the heat-depleted proteins were not significantly degraded and less ribosomes were recruited by excess new HSP mRNAs, the mild depletion of the many housekeeping proteins during heat shock was attributed to their slower replenishment. This differential protein expression pattern was reproduced by isothermal treatments with Hsp90 inhibitors. Unexpectedly, heat-treated cells accumulated 55 times more new molecules of HSPA8 (HSC70) than of the acknowledged heat-inducible isoform HSPA1A (HSP70), implying that when expressed as net copy number differences, rather than as mere "fold change" ratios, new biologically relevant information can be extracted from quantitative proteomic data. Raw data are available via ProteomeXchange with identifier PXD001666.
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Affiliation(s)
- Andrija Finka
- Department of Plant Molecular Biology, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland
- Laboratoire de Biophysique Statistique, School of Basic Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Vishal Sood
- Laboratoire de Biophysique Statistique, School of Basic Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Manfredo Quadroni
- Department of Biochemistry, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland
| | - Paolo De Los Rios
- Laboratoire de Biophysique Statistique, School of Basic Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Pierre Goloubinoff
- Department of Plant Molecular Biology, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland
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33
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Brock KP, Abraham AC, Amen T, Kaganovich D, England JL. Structural Basis for Modulation of Quality Control Fate in a Marginally Stable Protein. Structure 2015; 23:1169-78. [PMID: 26027734 PMCID: PMC4509718 DOI: 10.1016/j.str.2015.04.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 04/09/2015] [Accepted: 04/18/2015] [Indexed: 11/25/2022]
Abstract
The human von Hippel-Lindau (VHL) tumor suppressor is a marginally stable protein previously used as a model substrate of eukaryotic refolding and degradation pathways. When expressed in the absence of its cofactors, VHL cannot fold and is quickly degraded by the quality control machinery of the cell. We combined computational methods with in vivo experiments to examine the basis of the misfolding propensity of VHL. By expressing a set of randomly mutated VHL sequences in yeast, we discovered a more stable mutant form. Subsequent modeling suggested the mutation had caused a conformational change affecting cofactor and chaperone interaction, and this hypothesis was then confirmed by additional knockout and overexpression experiments targeting a yeast cofactor homolog. These findings offer a detailed structural basis for the modulation of quality control fate in a model misfolded protein and highlight burial mode modeling as a rapid means to detect functionally important conformational changes in marginally stable globular domains.
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Affiliation(s)
- Kelly P Brock
- Computational and Systems Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Ayelet-chen Abraham
- Department of Cell and Developmental Biology, Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem 91904, Israel
| | - Triana Amen
- Department of Cell and Developmental Biology, Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem 91904, Israel; Alexander Grass Center for Bioengineering, Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem 91904, Israel
| | - Daniel Kaganovich
- Department of Cell and Developmental Biology, Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem 91904, Israel.
| | - Jeremy L England
- Physics of Living Systems Group, Department of Physics, Massachusetts Institute of Technology, 400 Tech Square, Cambridge, MA 02139, USA.
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Moldavski O, Amen T, Levin-Zaidman S, Eisenstein M, Rogachev I, Brandis A, Kaganovich D, Schuldiner M. Lipid Droplets Are Essential for Efficient Clearance of Cytosolic Inclusion Bodies. Dev Cell 2015; 33:603-10. [PMID: 26004510 DOI: 10.1016/j.devcel.2015.04.015] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 02/17/2015] [Accepted: 04/21/2015] [Indexed: 11/24/2022]
Abstract
Exposing cells to folding stress causes a subset of their proteins to misfold and accumulate in inclusion bodies (IBs). IB formation and clearance are both active processes, but little is known about their mechanism. To shed light on this issue, we performed a screen with over 4,000 fluorescently tagged yeast proteins for co-localization with a model misfolded protein that marks IBs during folding stress. We identified 13 proteins that co-localize to IBs. Remarkably, one of these IB proteins, the uncharacterized and conserved protein Iml2, exhibited strong physical interactions with lipid droplet (LD) proteins. Indeed, we here show that IBs and LDs are spatially and functionally linked. We further demonstrate a mechanism for IB clearance via a sterol-based metabolite emanating from LDs. Our findings therefore uncover a function for Iml2 and LDs in regulating a critical stage of cellular proteostasis.
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Affiliation(s)
- Ofer Moldavski
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Triana Amen
- Department of Cell and Developmental Biology, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Smadar Levin-Zaidman
- Electron Microscopy Unit, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Miriam Eisenstein
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Ilana Rogachev
- Department for Biological Services, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Alexander Brandis
- Department for Biological Services, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Daniel Kaganovich
- Department of Cell and Developmental Biology, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem 91904, Israel.
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel.
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Pattabiraman S, Kaganovich D. Imperfect asymmetry: The mechanism governing asymmetric partitioning of damaged cellular components during mitosis. BIOARCHITECTURE 2015; 4:203-9. [PMID: 25941938 DOI: 10.1080/19490992.2015.1014213] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Aging is universally associated with organism-wide dysfunction and a decline in cellular fitness. From early development onwards, the efficiency of self-repair, energy production, and homeostasis all decrease. Due to the multiplicity of systems that undergo agingrelated decline, the mechanistic basis of organismal aging has been difficult to pinpoint. At the cellular level, however, recent work has provided important insight. Cellular aging is associated with the accumulation of several types of damage, in particular damage to the proteome and organelles. Groundbreaking studies have shown that replicative aging is the result of a rejuvenation mechanism that prevents the inheritance of damaged components during division, thereby confining the effects of aging to specific cells, while removing damage from others. Asymmetric inheritance of misfolded and aggregated proteins, as well as reduced mitochondria, has been shown in yeast. Until recently, however, it was not clear whether a similar mechanism operates in mammalian cells, which were thought to mostly divide symmetrically. Our group has recently shown that vimentin establishes mitotic polarity in immortalized mammalian cells, and mediates asymmetric partitioning of multiple factors through direct interaction. These findings prompt a provocative hypothesis: that intermediate filaments serve as asymmetric partitioning modules or "sponges" that, when expressed prior to mitosis, can "clean" emerging cells of the damage they have accumulated.
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Affiliation(s)
- Sundararaghavan Pattabiraman
- a Department of Cell and Developmental Biology ; Alexander Silberman Institute of Life Sciences; Hebrew University of Jerusalem ; Jerusalem , Israel
| | - Daniel Kaganovich
- a Department of Cell and Developmental Biology ; Alexander Silberman Institute of Life Sciences; Hebrew University of Jerusalem ; Jerusalem , Israel
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36
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The protein quality control machinery regulates its misassembled proteasome subunits. PLoS Genet 2015; 11:e1005178. [PMID: 25919710 PMCID: PMC4412499 DOI: 10.1371/journal.pgen.1005178] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 03/26/2015] [Indexed: 01/22/2023] Open
Abstract
Cellular toxicity introduced by protein misfolding threatens cell fitness and viability. Failure to eliminate these polypeptides is associated with various aggregation diseases. In eukaryotes, the ubiquitin proteasome system (UPS) plays a vital role in protein quality control (PQC), by selectively targeting misfolded proteins for degradation. While the assembly of the proteasome can be naturally impaired by many factors, the regulatory pathways that mediate the sorting and elimination of misassembled proteasomal subunits are poorly understood. Here, we reveal how the dysfunctional proteasome is controlled by the PQC machinery. We found that among the multilayered quality control mechanisms, UPS mediated degradation of its own misassembled subunits is the favored pathway. We also demonstrated that the Hsp42 chaperone mediates an alternative pathway, the accumulation of these subunits in cytoprotective compartments. Thus, we show that proteasome homeostasis is controlled through probing the level of proteasome assembly, and the interplay between UPS mediated degradation or their sorting into distinct cellular compartments. The accumulation of misfolded proteins threatens cell fitness and viability and their aggregation is commonly associated with numerous neurodegenerative disorders. Cells therefore rely on a number of protein quality control (PQC) pathways to prevent protein aggregation. In eukaryotes, the ubiquitin proteasome system (UPS), a supramolecular machinery that mediates the proteolysis of damaged or misfolded proteins, plays a vital role in PQC by selectively targeting proteins for degradation. Although the critical role-played by the UPS in PQC, and the severe consequences of impairing this pathway are well established, little was known about the mechanisms that control dysfunctional proteasome subunits. Here, we reveal that the interplay between UPS mediated degradation of its own misassembled subunits, and sorting them into cytoprotective compartments, a process that is mediated by the Hsp42 chaperone, determines how proteasome homeostasis is controlled in yeast cells. We believe that the mechanism of proteasome regulation by the PCQ in yeast may serve as a paradigm for understanding how homeostasis of this essential complex is controlled in major chronic neurodegenerative disorders in higher eukaryotes.
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The aggregation-prone intracellular serpin SRP-2 fails to transit the ER in Caenorhabditis elegans. Genetics 2015; 200:207-19. [PMID: 25786854 DOI: 10.1534/genetics.115.176180] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 03/17/2015] [Indexed: 11/18/2022] Open
Abstract
Familial encephalopathy with neuroserpin inclusions bodies (FENIB) is a serpinopathy that induces a rare form of presenile dementia. Neuroserpin contains a classical signal peptide and like all extracellular serine proteinase inhibitors (serpins) is secreted via the endoplasmic reticulum (ER)-Golgi pathway. The disease phenotype is due to gain-of-function missense mutations that cause neuroserpin to misfold and aggregate within the ER. In a previous study, nematodes expressing a homologous mutation in the endogenous Caenorhabditis elegans serpin, srp-2, were reported to model the ER proteotoxicity induced by an allele of mutant neuroserpin. Our results suggest that SRP-2 lacks a classical N-terminal signal peptide and is a member of the intracellular serpin family. Using confocal imaging and an ER colocalization marker, we confirmed that GFP-tagged wild-type SRP-2 localized to the cytosol and not the ER. Similarly, the aggregation-prone SRP-2 mutant formed intracellular inclusions that localized to the cytosol. Interestingly, wild-type SRP-2, targeted to the ER by fusion to a cleavable N-terminal signal peptide, failed to be secreted and accumulated within the ER lumen. This ER retention phenotype is typical of other obligate intracellular serpins forced to translocate across the ER membrane. Neuroserpin is a secreted protein that inhibits trypsin-like proteinase. SRP-2 is a cytosolic serpin that inhibits lysosomal cysteine peptidases. We concluded that SRP-2 is neither an ortholog nor a functional homolog of neuroserpin. Furthermore, animals expressing an aggregation-prone mutation in SRP-2 do not model the ER proteotoxicity associated with FENIB.
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