251
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Roth DM, Hutt DM, Tong J, Bouchecareilh M, Wang N, Seeley T, Dekkers JF, Beekman JM, Garza D, Drew L, Masliah E, Morimoto RI, Balch WE. Modulation of the maladaptive stress response to manage diseases of protein folding. PLoS Biol 2014; 12:e1001998. [PMID: 25406061 PMCID: PMC4236052 DOI: 10.1371/journal.pbio.1001998] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 10/07/2014] [Indexed: 12/31/2022] Open
Abstract
Diseases of protein folding arise because of the inability of an altered peptide sequence to properly engage protein homeostasis components that direct protein folding and function. To identify global principles of misfolding disease pathology we examined the impact of the local folding environment in alpha-1-antitrypsin deficiency (AATD), Niemann-Pick type C1 disease (NPC1), Alzheimer's disease (AD), and cystic fibrosis (CF). Using distinct models, including patient-derived cell lines and primary epithelium, mouse brain tissue, and Caenorhabditis elegans, we found that chronic expression of misfolded proteins not only triggers the sustained activation of the heat shock response (HSR) pathway, but that this sustained activation is maladaptive. In diseased cells, maladaptation alters protein structure-function relationships, impacts protein folding in the cytosol, and further exacerbates the disease state. We show that down-regulation of this maladaptive stress response (MSR), through silencing of HSF1, the master regulator of the HSR, restores cellular protein folding and improves the disease phenotype. We propose that restoration of a more physiological proteostatic environment will strongly impact the management and progression of loss-of-function and gain-of-toxic-function phenotypes common in human disease.
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Affiliation(s)
- Daniela Martino Roth
- Department of Cell Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Darren M. Hutt
- Department of Cell Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Jiansong Tong
- Department of Cell Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Marion Bouchecareilh
- Department of Cell Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Ning Wang
- Department of Molecular Biosciences, Rice Institute for Biomedical Research, Northwestern University, Evanston, Illinois, United States of America
| | - Theo Seeley
- Department of Cell Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Johanna F. Dekkers
- Department of Pediatric Pulmonology, Wilhelmina Children's Hospital, University Medical Centre, Utrecht, The Netherlands
- Laboratory of Translational Immunology, Wilhelmina Children's Hospital, University Medical Centre, Utrecht, The Netherlands
| | - Jeffrey M. Beekman
- Department of Pediatric Pulmonology, Wilhelmina Children's Hospital, University Medical Centre, Utrecht, The Netherlands
- Laboratory of Translational Immunology, Wilhelmina Children's Hospital, University Medical Centre, Utrecht, The Netherlands
| | - Dan Garza
- Proteostasis Therapeutics Inc., Cambridge, Massachusetts, United States of America
| | - Lawrence Drew
- Proteostasis Therapeutics Inc., Cambridge, Massachusetts, United States of America
| | - Eliezer Masliah
- Department of Neurosciences, University of California, San Diego, La Jolla, California, United States of America
| | - Richard I. Morimoto
- Department of Molecular Biosciences, Rice Institute for Biomedical Research, Northwestern University, Evanston, Illinois, United States of America
| | - William E. Balch
- Department of Cell Biology, The Scripps Research Institute, La Jolla, California, United States of America
- The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California, United States of America
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California, United States of America
- The Institute for Childhood and Neglected Diseases, The Scripps Research Institute, La Jolla, California, United States of America
- * E-mail:
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252
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The amazing ubiquitin-proteasome system: structural components and implication in aging. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 314:171-237. [PMID: 25619718 DOI: 10.1016/bs.ircmb.2014.09.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Proteome quality control (PQC) is critical for the maintenance of cellular functionality and it is assured by the curating activity of the proteostasis network (PN). PN is constituted of several complex protein machines that under conditions of proteome instability aim to, firstly identify, and then, either rescue or degrade nonnative polypeptides. Central to the PN functionality is the ubiquitin-proteasome system (UPS) which is composed from the ubiquitin-conjugating enzymes and the proteasome; the latter is a sophisticated multi-subunit molecular machine that functions in a bimodal way as it degrades both short-lived ubiquitinated normal proteins and nonfunctional polypeptides. UPS is also involved in PQC of the nucleus, the endoplasmic reticulum and the mitochondria and it also interacts with the other main cellular degradation axis, namely the autophagy-lysosome system. UPS functionality is optimum in the young organism but it is gradually compromised during aging resulting in increasing proteotoxic stress; these effects correlate not only with aging but also with most age-related diseases. Herein, we present a synopsis of the UPS components and of their functional alterations during cellular senescence or in vivo aging. We propose that mild UPS activation in the young organism will, likely, promote antiaging effects and/or suppress age-related diseases.
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253
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Stem cell aging: mechanisms, regulators and therapeutic opportunities. Nat Med 2014; 20:870-80. [PMID: 25100532 DOI: 10.1038/nm.3651] [Citation(s) in RCA: 479] [Impact Index Per Article: 47.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2014] [Accepted: 07/09/2014] [Indexed: 12/14/2022]
Abstract
Aging tissues experience a progressive decline in homeostatic and regenerative capacities, which has been attributed to degenerative changes in tissue-specific stem cells, stem cell niches and systemic cues that regulate stem cell activity. Understanding the molecular pathways involved in this age-dependent deterioration of stem cell function will be critical for developing new therapies for diseases of aging that target the specific causes of age-related functional decline. Here we explore key molecular pathways that are commonly perturbed as tissues and stem cells age and degenerate. We further consider experimental evidence both supporting and refuting the notion that modulation of these pathways per se can reverse aging phenotypes. Finally, we ask whether stem cell aging establishes an epigenetic 'memory' that is indelibly written or one that can be reset.
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254
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Wiemer M, Osiewacz HD. The proteasome activity reporter GFP-Cl1 is degraded by autophagy in the aging model Podospora anserina. F1000Res 2014; 3:230. [PMID: 25520781 PMCID: PMC4264638 DOI: 10.12688/f1000research.5337.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/25/2014] [Indexed: 01/08/2023] Open
Abstract
The degradation of damaged proteins is an important vital function especially during aging and stress. The ubiquitin proteasome system is one of the major cellular machineries for protein degradation. Health and longevity are associated with high proteasome activity. To demonstrate such a role in aging of Podospora anserina, we first analyzed the transcript and protein abundance of selected proteasome components in wild-type cultures of different age. No significant differences were observed. Next, in order to increase the overall proteasome abundance we generated strains overexpressing the catalytic proteasome subunits PaPRE2 and PaPRE3. Although transcript levels were strongly increased, no substantial effect on the abundance of the corresponding proteins was observed. Finally, the analysis of the P. anserina strains expressing the sequence coding for the CL1 degron fused to the Gfp gene revealed no evidence for degradation of the GFP-CL1 fusion protein by the proteasome. Instead, our results demonstrate the degradation of the CL1-degron sequence via autophagy, indicating that basal autophagy appears to be a very effective protein quality control pathway in P. anserina.
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Affiliation(s)
- Matthias Wiemer
- Institute of Molecular Biosciences and Cluster of Excellence Frankfurt Macromolecular Complexes; Department of Biosciences, J W Goethe University, Frankfurt, 60438, Germany
| | - Heinz D Osiewacz
- Institute of Molecular Biosciences and Cluster of Excellence Frankfurt Macromolecular Complexes; Department of Biosciences, J W Goethe University, Frankfurt, 60438, Germany
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255
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Hipp MS, Park SH, Hartl FU. Proteostasis impairment in protein-misfolding and -aggregation diseases. Trends Cell Biol 2014; 24:506-14. [DOI: 10.1016/j.tcb.2014.05.003] [Citation(s) in RCA: 449] [Impact Index Per Article: 44.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 05/19/2014] [Accepted: 05/20/2014] [Indexed: 12/27/2022]
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256
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Jansen AHP, Reits EAJ, Hol EM. The ubiquitin proteasome system in glia and its role in neurodegenerative diseases. Front Mol Neurosci 2014; 7:73. [PMID: 25152710 PMCID: PMC4126450 DOI: 10.3389/fnmol.2014.00073] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 07/10/2014] [Indexed: 12/12/2022] Open
Abstract
The ubiquitin proteasome system (UPS) is crucial for intracellular protein homeostasis and for degradation of aberrant and damaged proteins. The accumulation of ubiquitinated proteins is a hallmark of many neurodegenerative diseases, including amyotrophic lateral sclerosis, Alzheimer’s, Parkinson’s, and Huntington’s disease, leading to the hypothesis that proteasomal impairment is contributing to these diseases. So far, most research related to the UPS in neurodegenerative diseases has been focused on neurons, while glial cells have been largely disregarded in this respect. However, glial cells are essential for proper neuronal function and adopt a reactive phenotype in neurodegenerative diseases, thereby contributing to an inflammatory response. This process is called reactive gliosis, which in turn affects UPS function in glial cells. In many neurodegenerative diseases, mostly neurons show accumulation and aggregation of ubiquitinated proteins, suggesting that glial cells may be better equipped to maintain proper protein homeostasis. During an inflammatory reaction, the immunoproteasome is induced in glia, which may contribute to a more efficient degradation of disease-related proteins. Here we review the role of the UPS in glial cells in various neurodegenerative diseases, and we discuss how studying glial cell function might provide essential information in unraveling mechanisms of neurodegenerative diseases.
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Affiliation(s)
- Anne H P Jansen
- Department of Cell Biology and Histology, Academic Medical Center Amsterdam, Netherlands
| | - Eric A J Reits
- Department of Cell Biology and Histology, Academic Medical Center Amsterdam, Netherlands
| | - Elly M Hol
- Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht Utrecht, Netherlands ; Netherlands Institute for Neuroscience, Institute of the Royal Netherlands Academy of Arts and Sciences Amsterdam, Netherlands ; Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam Netherlands
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257
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Hoppe T. Limited proteolysis: DisRUPting proteasomal inhibition. Curr Biol 2014; 24:R693-5. [PMID: 25093561 DOI: 10.1016/j.cub.2014.06.056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The 26S proteasome is a protease complex that completely degrades substrate proteins marked with a chain of ubiquitins, but is also able to perform endoproteolytic cleavage. A new study now demonstrates that regulated ubiquitin-proteasome-dependent processing ameliorates proteasomal inhibition.
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Affiliation(s)
- Thorsten Hoppe
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph Stelzmann Str. 26, 50931 Cologne, Germany.
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258
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Dantuma NP, Bott LC. The ubiquitin-proteasome system in neurodegenerative diseases: precipitating factor, yet part of the solution. Front Mol Neurosci 2014; 7:70. [PMID: 25132814 PMCID: PMC4117186 DOI: 10.3389/fnmol.2014.00070] [Citation(s) in RCA: 213] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2014] [Accepted: 07/09/2014] [Indexed: 01/17/2023] Open
Abstract
The ubiquitin-proteasome system (UPS) has been implicated in neurodegenerative diseases based on the presence of deposits consisting of ubiquitylated proteins in affected neurons. It has been postulated that aggregation-prone proteins associated with these disorders, such as α-synuclein, β-amyloid peptide, and polyglutamine proteins, compromise UPS function, and delay the degradation of other proteasome substrates. Many of these substrates play important regulatory roles in signaling, cell cycle progression, or apoptosis, and their inadvertent stabilization due to an overloaded and improperly functioning UPS may thus be responsible for cellular demise in neurodegeneration. Over the past decade, numerous studies have addressed the UPS dysfunction hypothesis using various model systems and techniques that differ in their readout and sensitivity. While an inhibitory effect of some disease proteins on the UPS has been demonstrated, increasing evidence attests that the UPS remains operative in many disease models, which opens new possibilities for treatment. In this review, we will discuss the paradigm shift that repositioned the UPS from being a prime suspect in the pathophysiology of neurodegeneration to an attractive therapeutic target that can be harnessed to accelerate the clearance of disease-linked proteins.
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Affiliation(s)
- Nico P Dantuma
- Department of Cell and Molecular Biology, Karolinska Institutet Stockholm, Sweden
| | - Laura C Bott
- Department of Cell and Molecular Biology, Karolinska Institutet Stockholm, Sweden ; Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health Bethesda, MD, USA
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259
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Chaperoning proteins for destruction: diverse roles of Hsp70 chaperones and their co-chaperones in targeting misfolded proteins to the proteasome. Biomolecules 2014; 4:704-24. [PMID: 25036888 PMCID: PMC4192669 DOI: 10.3390/biom4030704] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 05/31/2014] [Accepted: 06/24/2014] [Indexed: 01/04/2023] Open
Abstract
Molecular chaperones were originally discovered as heat shock-induced proteins that facilitate proper folding of proteins with non-native conformations. While the function of chaperones in protein folding has been well documented over the last four decades, more recent studies have shown that chaperones are also necessary for the clearance of terminally misfolded proteins by the Ub-proteasome system. In this capacity, chaperones protect misfolded degradation substrates from spontaneous aggregation, facilitate their recognition by the Ub ligation machinery and finally shuttle the ubiquitylated substrates to the proteasome. The physiological importance of these functions is manifested by inefficient proteasomal degradation and the accumulation of protein aggregates during ageing or in certain neurodegenerative diseases, when chaperone levels decline. In this review, we focus on the diverse roles of stress-induced chaperones in targeting misfolded proteins to the proteasome and the consequences of their compromised activity. We further discuss the implications of these findings to the identification of new therapeutic targets for the treatment of amyloid diseases.
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260
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Affiliation(s)
- Harm H Kampinga
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands.
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261
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Sha Z, Goldberg AL. Proteasome-mediated processing of Nrf1 is essential for coordinate induction of all proteasome subunits and p97. Curr Biol 2014; 24:1573-1583. [PMID: 24998528 DOI: 10.1016/j.cub.2014.06.004] [Citation(s) in RCA: 167] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 05/21/2014] [Accepted: 06/02/2014] [Indexed: 12/30/2022]
Abstract
BACKGROUND Proteasome inhibitors are widely used in the treatment of multiple myeloma and as research tools. Additionally, diminished proteasome function may contribute to neuronal dysfunction. In response to these inhibitors, cells enhance the expression of proteasome subunits by the transcription factor Nrf1. Here, we investigate the mechanisms by which decreased proteasome function triggers production of new proteasomes via Nrf1. RESULTS Exposure of myeloma or neuronal cells to proteasome inhibitors (bortezomib, epoxomicin, and MG132), but not to proteotoxic or ER stress, caused a 2- to 4-fold increase within 4 hr in mRNAs for all 26S subunits. In addition, p97 and its cofactors (Npl4, Ufd1, and p47), PA200, and USP14 were induced, but expression of immunoproteasome-specific subunits was suppressed. Nrf1 mediates this induction of proteasomes and p97, but only upon exposure to low concentrations of inhibitors that partially inhibit proteolysis. Surprisingly, high concentrations of these inhibitors prevent this compensatory response. Nrf1 is normally ER-bound, and its release requires its deglycosylation and ubiquitination. Normally ubiquitinated Nrf1 is rapidly degraded, but when partially inhibited, proteasomes carry out limited proteolysis and release the processed Nrf1 (lacking its N-terminal region) from the ER, which allows it to enter the nucleus and promote gene expression. CONCLUSIONS When fully active, proteasomes degrade Nrf1, but when partially inhibited, they perform limited proteolysis that generates the active form of Nrf1. This elegant mechanism allows cells to compensate for reduced proteasome function by enhancing production of 26S subunits and p97.
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Affiliation(s)
- Zhe Sha
- Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
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262
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Wolff S, Weissman JS, Dillin A. Differential scales of protein quality control. Cell 2014; 157:52-64. [PMID: 24679526 DOI: 10.1016/j.cell.2014.03.007] [Citation(s) in RCA: 177] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Revised: 03/06/2014] [Accepted: 03/07/2014] [Indexed: 02/06/2023]
Abstract
Proteins are notorious for their unpleasant behavior-continually at risk of misfolding, collecting damage, aggregating, and causing toxicity and disease. To counter these challenges, cells have evolved elaborate chaperone and quality control networks that can resolve damage at the level of the protein, organelle, cell, or tissue. On the smallest scale, the integrity of individual proteins is monitored during their synthesis. On a larger scale, cells use compartmentalized defenses and networks of communication, capable sometimes of signaling between cells, to respond to changes in the proteome's health. Together, these layered defenses help protect cells from damaged proteins.
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Affiliation(s)
- Suzanne Wolff
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Jonathan S Weissman
- Department of Cellular and Molecular Pharmacology, California Institute of Quantitative Biology, Center for RNA Systems Biology, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA.
| | - Andrew Dillin
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720, USA.
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263
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Chondrogianni N, Sakellari M, Lefaki M, Papaevgeniou N, Gonos ES. Proteasome activation delays aging in vitro and in vivo. Free Radic Biol Med 2014; 71:303-320. [PMID: 24681338 DOI: 10.1016/j.freeradbiomed.2014.03.031] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 03/18/2014] [Accepted: 03/18/2014] [Indexed: 02/02/2023]
Abstract
Aging is a natural biological process that is characterized by a progressive accumulation of macromolecular damage. In the proteome, aging is accompanied by decreased protein homeostasis and function of the major cellular proteolytic systems, leading to the accumulation of unfolded, misfolded, or aggregated proteins. In particular, the proteasome is responsible for the removal of normal as well as damaged or misfolded proteins. Extensive work during the past several years has clearly demonstrated that proteasome activation by either genetic means or use of compounds significantly retards aging. Importantly, this represents a common feature across evolution, thereby suggesting proteasome activation to be an evolutionarily conserved mechanism of aging and longevity regulation. This review article reports on the means of function of these proteasome activators and how they regulate aging in various species.
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Affiliation(s)
- Niki Chondrogianni
- National Hellenic Research Foundation, Institute of Biology, Medicinal Chemistry, and Biotechnology, 116 35 Athens, Greece.
| | - Marianthi Sakellari
- National Hellenic Research Foundation, Institute of Biology, Medicinal Chemistry, and Biotechnology, 116 35 Athens, Greece; Örebro University Medical School, Örebro, Sweden
| | - Maria Lefaki
- National Hellenic Research Foundation, Institute of Biology, Medicinal Chemistry, and Biotechnology, 116 35 Athens, Greece
| | - Nikoletta Papaevgeniou
- National Hellenic Research Foundation, Institute of Biology, Medicinal Chemistry, and Biotechnology, 116 35 Athens, Greece
| | - Efstathios S Gonos
- National Hellenic Research Foundation, Institute of Biology, Medicinal Chemistry, and Biotechnology, 116 35 Athens, Greece; Örebro University Medical School, Örebro, Sweden
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264
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Fabre B, Lambour T, Garrigues L, Ducoux-Petit M, Amalric F, Monsarrat B, Burlet-Schiltz O, Bousquet-Dubouch MP. Label-Free Quantitative Proteomics Reveals the Dynamics of Proteasome Complexes Composition and Stoichiometry in a Wide Range of Human Cell Lines. J Proteome Res 2014; 13:3027-37. [DOI: 10.1021/pr500193k] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Bertrand Fabre
- CNRS; IPBS (Institut de Pharmacologie et de Biologie Structurale); 205 route de Narbonne, F-31077 Toulouse, France
- Université de Toulouse; UPS; IPBS; F-31077 Toulouse, France
| | - Thomas Lambour
- CNRS; IPBS (Institut de Pharmacologie et de Biologie Structurale); 205 route de Narbonne, F-31077 Toulouse, France
- Université de Toulouse; UPS; IPBS; F-31077 Toulouse, France
| | - Luc Garrigues
- CNRS; IPBS (Institut de Pharmacologie et de Biologie Structurale); 205 route de Narbonne, F-31077 Toulouse, France
- Université de Toulouse; UPS; IPBS; F-31077 Toulouse, France
| | - Manuelle Ducoux-Petit
- CNRS; IPBS (Institut de Pharmacologie et de Biologie Structurale); 205 route de Narbonne, F-31077 Toulouse, France
- Université de Toulouse; UPS; IPBS; F-31077 Toulouse, France
| | - François Amalric
- CNRS; IPBS (Institut de Pharmacologie et de Biologie Structurale); 205 route de Narbonne, F-31077 Toulouse, France
- Université de Toulouse; UPS; IPBS; F-31077 Toulouse, France
| | - Bernard Monsarrat
- CNRS; IPBS (Institut de Pharmacologie et de Biologie Structurale); 205 route de Narbonne, F-31077 Toulouse, France
- Université de Toulouse; UPS; IPBS; F-31077 Toulouse, France
| | - Odile Burlet-Schiltz
- CNRS; IPBS (Institut de Pharmacologie et de Biologie Structurale); 205 route de Narbonne, F-31077 Toulouse, France
- Université de Toulouse; UPS; IPBS; F-31077 Toulouse, France
| | - Marie-Pierre Bousquet-Dubouch
- CNRS; IPBS (Institut de Pharmacologie et de Biologie Structurale); 205 route de Narbonne, F-31077 Toulouse, France
- Université de Toulouse; UPS; IPBS; F-31077 Toulouse, France
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265
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Tan SM, Altschuler G, Zhao TY, Ang HS, Yang H, Lim B, Vardy L, Hide W, Thomson AM, Lareu RR. Divergent LIN28-mRNA associations result in translational suppression upon the initiation of differentiation. Nucleic Acids Res 2014; 42:7997-8007. [PMID: 24860167 PMCID: PMC4081066 DOI: 10.1093/nar/gku430] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
LIN28 function is fundamental to the activity and behavior of human embryonic stem cells (hESCs) and induced pluripotent stem cells. Its main roles in these cell types are the regulation of translational efficiency and let-7 miRNA maturation. However, LIN28-associated mRNA cargo shifting and resultant regulation of translational efficiency upon the initiation of differentiation remain unknown. An RNA-immunoprecipitation and microarray analysis protocol, eRIP, that has high specificity and sensitivity was developed to test endogenous LIN28-associated mRNA cargo shifting. A combined eRIP and polysome analysis of early stage differentiation of hESCs with two distinct differentiation cues revealed close similarities between the dynamics of LIN28 association and translational modulation of genes involved in the Wnt signaling, cell cycle, RNA metabolism and proteasomal pathways. Our data demonstrate that change in translational efficiency is a major contributor to early stages of differentiation of hESCs, in which LIN28 plays a central role. This implies that eRIP analysis of LIN28-associated RNA cargoes may be used for rapid functional quality control of pluripotent stem cells under manufacture for therapeutic applications.
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Affiliation(s)
- Shen Mynn Tan
- Stem Cell and Developmental Biology, Genome Institute of Singapore, Agency for Science Technology and Research (A*STAR), 138672, Singapore
| | - Gabriel Altschuler
- Department of Biostatistics, Harvard School of Public Health, Boston, MA 02115, USA
| | - Tian Yun Zhao
- Institute of Medical Biology, A*STAR, 138648, Singapore
| | - Haw Siang Ang
- Cancer Science Institute, National University of Singapore (NUS), 117599, Singapore
| | - Henry Yang
- Cancer Science Institute, National University of Singapore (NUS), 117599, Singapore
| | - Bing Lim
- Stem Cell and Developmental Biology, Genome Institute of Singapore, Agency for Science Technology and Research (A*STAR), 138672, Singapore
| | - Leah Vardy
- Institute of Medical Biology, A*STAR, 138648, Singapore
| | - Winston Hide
- Department of Biostatistics, Harvard School of Public Health, Boston, MA 02115, USA
| | - Andrew M Thomson
- Stem Cell and Developmental Biology, Genome Institute of Singapore, Agency for Science Technology and Research (A*STAR), 138672, Singapore
| | - Ricky R Lareu
- Department of Orthopedic Surgery, NUS Tissue Engineering Program, Yong Loo Lin School of Medicine, NUS, 119228, Singapore and School of Pharmacy, CHIRI Biosciences, Curtin University, Western Australia 6102, Australia
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266
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Saez I, Vilchez D. The Mechanistic Links Between Proteasome Activity, Aging and Age-related Diseases. Curr Genomics 2014; 15:38-51. [PMID: 24653662 PMCID: PMC3958958 DOI: 10.2174/138920291501140306113344] [Citation(s) in RCA: 219] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 01/13/2014] [Accepted: 01/15/2014] [Indexed: 01/17/2023] Open
Abstract
Damaged and misfolded proteins accumulate during the aging process, impairing cell function and tissue homeostasis. These perturbations to protein homeostasis (proteostasis) are hallmarks of age-related neurodegenerative disorders such as Alzheimer’s, Parkinson’s or Huntington’s disease. Damaged proteins are degraded by cellular clearance mechanisms such as the proteasome, a key component of the proteostasis network. Proteasome activity declines during aging, and proteasomal dysfunction is associated with late-onset disorders. Modulation of proteasome activity extends lifespan and protects organisms from symptoms associated with proteostasis disorders. Here we review the links between proteasome activity, aging and neurodegeneration. Additionally, strategies to modulate proteasome activity and delay the onset of diseases associated to proteasomal dysfunction are discussed herein.
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Affiliation(s)
- Isabel Saez
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Co-logne, Joseph Stelzmann Strasse 26, 50931 Cologne, Germany
| | - David Vilchez
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Co-logne, Joseph Stelzmann Strasse 26, 50931 Cologne, Germany
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267
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Strikoudis A, Guillamot M, Aifantis I. Regulation of stem cell function by protein ubiquitylation. EMBO Rep 2014; 15:365-82. [PMID: 24652853 DOI: 10.1002/embr.201338373] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Tissue homeostasis depends largely on the ability to replenish impaired or aged cells. Thus, tissue-resident stem cells need to provide functional progeny throughout the lifetime of an organism. Significant work in the past years has characterized how stem cells integrate signals from their environment to shape regulatory transcriptional networks and chromatin-regulating factors that control stem cell differentiation or maintenance. There is increasing interest in how post-translational modifications, and specifically ubiquitylation, control these crucial decisions. Ubiquitylation modulates the stability and function of important factors that regulate key processes in stem cell behavior. In this review, we analyze the role of ubiquitylation in embryonic stem cells and different adult multipotent stem cell systems and discuss the underlying mechanisms that control the balance between quiescence, self-renewal, and differentiation. We also discuss deregulated processes of ubiquitin-mediated protein degradation that lead to the development of tumor-initiating cells.
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Affiliation(s)
- Alexandros Strikoudis
- Howard Hughes Medical Institute New York University School of Medicine, New York, NY, USA
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268
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Webb AE, Brunet A. FOXO transcription factors: key regulators of cellular quality control. Trends Biochem Sci 2014; 39:159-69. [PMID: 24630600 DOI: 10.1016/j.tibs.2014.02.003] [Citation(s) in RCA: 398] [Impact Index Per Article: 39.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 02/05/2014] [Accepted: 02/07/2014] [Indexed: 12/13/2022]
Abstract
FOXO transcription factors are conserved regulators of longevity downstream of insulin signaling. These transcription factors integrate signals emanating from nutrient deprivation and stress stimuli to coordinate programs of genes involved in cellular metabolism and resistance to oxidative stress. Here, we discuss emerging evidence for a pivotal role of FOXO factors in promoting the expression of genes involved in autophagy and the ubiquitin-proteasome system--two cell clearance processes that are essential for maintaining organelle and protein homeostasis (proteostasis). The ability of FOXO to maintain cellular quality control appears to be critical in processes and pathologies where damaged proteins and organelles accumulate, including aging and neurodegenerative diseases.
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Affiliation(s)
- Ashley E Webb
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Anne Brunet
- Department of Genetics, Stanford University, Stanford, CA 94305, USA; Glenn Laboratories for the Biology of Aging at Stanford, Stanford, CA 94305, USA.
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269
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Haematopoietic stem cells require a highly regulated protein synthesis rate. Nature 2014; 509:49-54. [PMID: 24670665 PMCID: PMC4015626 DOI: 10.1038/nature13035] [Citation(s) in RCA: 457] [Impact Index Per Article: 45.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2013] [Accepted: 01/15/2014] [Indexed: 12/19/2022]
Abstract
Many aspects of cellular physiology remain unstudied in somatic stem cells. For example, there are almost no data on protein synthesis in any somatic stem cell. We found that the amount of protein synthesized per hour in haematopoietic stem cells (HSCs) in vivo was lower than in most other haematopoietic cells, even if we controlled for differences in cell cycle status or forced HSCs to undergo self-renewing divisions. Reduced ribosome function in Rpl24Bst/+ mice further reduced protein synthesis in HSCs and impaired HSC function. Pten deletion increased protein synthesis in HSCs but also reduced HSC function. Rpl24Bst/+ cell-autonomously rescued the effects of Pten deletion in HSCs, blocking the increase in protein synthesis, restoring HSC function, and delaying leukaemogenesis. Pten deficiency thus depletes HSCs and promotes leukaemia partly by increasing protein synthesis. Either increased or decreased protein synthesis impairs HSC function.
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270
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Proteostasis and aging of stem cells. Trends Cell Biol 2014; 24:161-70. [DOI: 10.1016/j.tcb.2013.09.002] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 09/04/2013] [Accepted: 09/04/2013] [Indexed: 12/13/2022]
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271
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Rege J, Nakamura Y, Wang T, Merchen TD, Sasano H, Rainey WE. Transcriptome profiling reveals differentially expressed transcripts between the human adrenal zona fasciculata and zona reticularis. J Clin Endocrinol Metab 2014; 99:E518-27. [PMID: 24423296 PMCID: PMC3942232 DOI: 10.1210/jc.2013-3198] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
CONTEXT The human adrenal zona fasciculata (ZF) and zona reticularis (ZR) are responsible for the production of cortisol and 19-carbon steroids (often called adrenal androgens), respectively. However, the gene profiles and exact molecular mechanisms leading to the functional phenotype of the ZF and ZR are still not clearly defined. In the present study, we identified the transcripts that are differentially expressed in the ZF and ZR. OBJECTIVE The objective of the study was to compare the transcriptome profiles of ZF and ZR. DESIGN AND METHODS ZF and ZR were microdissected from 10 human adrenals. Total RNA was extracted from 10 ZF/ZR pairs and hybridized to Illumina microarray chips. The 10 most differentially expressed transcripts were studied with quantitative RT-PCR (qPCR). Immunohistochemistry was also performed on four zone-specific genes. RESULTS Microarray results demonstrated that only 347 transcripts of the 47 231 were significantly different by 2-fold or greater in the ZF and ZR. ZF had 195 transcripts with 2-fold or greater increase compared with its paired ZR, whereas ZR was found to have 152 transcripts with 2-fold or greater higher expression than in ZF. Microarray and qPCR analysis of transcripts encoding steroidogenic enzymes (n = 10) demonstrated that only 3β-hydroxysteroid dehydrogenase, steroid sulfotransferase, type 5 17β-hydroxysteroid dehydrogenase, and cytochrome b5 were significantly different. Immunohistochemistry and qPCR studies confirmed that the ZF had an increased expression of lymphoid enhancer-binding factor 1 and nephroblastoma overexpressed, whereas ZR showed an increased expression of solute carrier family 27 (fatty acid transporter) (SLC27A2), member 2 and TSPAN12 (tetraspanin 12) CONCLUSION: Microarray revealed several novel candidate genes for elucidating the molecular mechanisms governing the ZF and ZR, thereby increasing our understanding of the functional zonation of these two adrenocortical zones.
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Affiliation(s)
- Juilee Rege
- Departments of Molecular and Integrative Physiology and Internal Medicine (J.R., W.E.R.), University of Michigan Medical School, Ann Arbor, Michigan 48109; Departments of Physiology (J.R., T.W., W.E.R.) and Surgery (T.D.M.), Georgia Regents University, Augusta, Georgia 30912; and Department of Pathology (Y.N., H.S.), Tohoku University School of Medicine, Sendai 980-8579, Japan
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272
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Abstract
Protein homoeostasis is a fundamental requirement for all living cells in order to survive in a dynamic surrounding. Proper levels of AIRAPL (arsenite-inducible RNA-associated protein-like protein) (ZFAND2B) are required in order to maintain cellular folding capacity in metazoans, and functional impairment of AIRAPL results in acceleration of aging and protein aggregation. However, the cellular roles of AIRAPL in this process are not known. In the present paper, we report that AIRAPL binds and forms a complex with p97 [VCP (valosin-containing protein)/Cdc48], Ubxd8 (ubiquitin regulatory X domain 8), Npl4-Ufd1, Derlin-1 and Bag6 on the ER (endoplasmic reticulum) membrane. In spite of the fact that AIRAPL complex partners are involved in the ERAD (ER-associated degradation) process, AIRAPL knockdown does not show any impairment in ERAD substrate degradation. However, translocation into the ER of a subset of ERAD- and non-ERAD-secreted proteins are regulated by AIRAPL. The ability to regulate translocation by the p97-AIRAPL complex is entirely dependent on the proteins' signal peptide. Our results demonstrate a p97 complex regulating translocation into the ER in a signal-peptide-dependent manner.
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273
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Schröter F, Adjaye J. The proteasome complex and the maintenance of pluripotency: sustain the fate by mopping up? Stem Cell Res Ther 2014; 5:24. [PMID: 25127410 PMCID: PMC4035846 DOI: 10.1186/scrt413] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
The proteasome is a multi-enzyme complex responsible for orchestrating protein quality control by degrading misfolded, damaged, abnormal and foreign proteins. Studies related to the association of the proteasomal system in the preservation of self-renewal in both human and mouse pluripotent cells are sparse, and therefore a clear indication of the emergence of a new and important field of research. Under specific conditions the standard proteasome switches to the newly synthesized immunoproteasome, a catalytically active protein chamber also involved in the regulation of protein homeostasis, cell signaling and gene expression. Herein we review recent data to help elucidate and highlight the pivotal role of the proteasome complex, constitutive as well as inducible, in the regulation of self-renewal, pluripotency and differentiation of both embryonic and induced pluripotent stem cells. The proteasome that is endowed with enhanced proteolytic activity maintains self-renewal by regulating gene expression. In addition to protein degradation, the proteasome activator PA28, compartments of the 19S regulatory particle and key members of the ubiquitin pathway dictate the fate of a pluripotent stem cell. We anticipate that our observations will stimulate active research in this new and emerging theme related to stem cell biology, disease and regenerative medicine.
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274
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The ubiquitin proteasome system in Caenorhabditis elegans and its regulation. Redox Biol 2014; 2:333-47. [PMID: 24563851 PMCID: PMC3926112 DOI: 10.1016/j.redox.2014.01.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 01/08/2014] [Accepted: 01/10/2014] [Indexed: 11/20/2022] Open
Abstract
Protein degradation constitutes a major cellular function that is responsible for maintenance of the normal cellular physiology either through the degradation of normal proteins or through the elimination of damaged proteins. The Ubiquitin–Proteasome System (UPS)1 is one of the main proteolytic systems that orchestrate protein degradation. Given that up- and down- regulation of the UPS system has been shown to occur in various normal (such as ageing) and pathological (such as neurodegenerative diseases) processes, the exogenous modulation of the UPS function and activity holds promise of (a) developing new therapeutic interventions against various diseases and (b) establishing strategies to maintain cellular homeostasis. Since the proteasome genes are evolutionarily conserved, their role can be dissected in simple model organisms, such as the nematode, Caenorhabditis elegans. In this review, we survey findings on the redox regulation of the UPS in C. elegans showing that the nematode is an instrumental tool in the identification of major players in the UPS pathway. Moreover, we specifically discuss UPS-related genes that have been modulated in the nematode and in human cells and have resulted in similar effects thus further exhibiting the value of this model in the study of the UPS. UPS is one of the main proteolytic systems that orchestrate protein degradation. Proteasome function can be dissected in Caenorhabditis elegans. Nematodes can be used in the identification of major players in the UPS pathway.
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275
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Ameliorating replicative senescence of human bone marrow stromal cells by PSMB5 overexpression. Biochem Biophys Res Commun 2014; 443:1182-8. [PMID: 24393841 DOI: 10.1016/j.bbrc.2013.12.113] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Accepted: 12/20/2013] [Indexed: 02/08/2023]
Abstract
Multipotent human bone marrow stromal cells (hBMSCs) potentially serve as a source for cell-based therapy in regenerative medicine. However, in vitro expansion was inescapably accompanied with cell senescence, characterized by inhibited proliferation and compromised pluripotency. We have previously demonstrated that this aging process is closely associated with reduced 20S proteasomal activity, with down-regulation of rate-limiting catalytic β-subunits particularly evident. In the present study, we confirmed that proteasomal activity directly contributes to senescence of hBMSCs, which could be reversed by overexpression of the β5-subunit (PSMB5). Knocking down PSMB5 led to decreased proteasomal activity concurrent with reduced cell proliferation in early-stage hBMSCs, which is similar to the senescent phenotype observed in late-stage cells. In contrast, overexpressing PSMB5 in late-stage cells efficiently restored the normal activity of 20S proteasomes and promoted cell growth, possibly via upregulating the Cyclin D1/CDK4 complex. Additionally, PSMB5 could enhance cell resistance to oxidative stress, as evidenced by the increased cell survival upon exposing senescent hBMSCs to hydrogen peroxide. Furthermore, PSMB5 overexpression retained the pluripotency of late-stage hBMSCs by facilitating their neural differentiation both in vitro and in vivo. Collectively, our work reveals a critical role of PSMB5 in 20S proteasome-mediated protection against replicative senescence, pointing to a possible strategy for maintaining the integrity of culture-expanded hBMSCs by manipulating the expression of PSMB5.
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276
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Role of protein misfolding and proteostasis deficiency in protein misfolding diseases and aging. Int J Cell Biol 2013; 2013:638083. [PMID: 24348562 PMCID: PMC3855986 DOI: 10.1155/2013/638083] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 10/08/2013] [Accepted: 10/09/2013] [Indexed: 11/29/2022] Open
Abstract
The misfolding, aggregation, and tissue accumulation of proteins are common events in diverse chronic diseases, known as protein misfolding disorders. Many of these diseases are associated with aging, but the mechanism for this connection is unknown. Recent evidence has shown that the formation and accumulation of protein aggregates may be a process frequently occurring during normal aging, but it is unknown whether protein misfolding is a cause or a consequence of aging. To combat the formation of these misfolded aggregates cells have developed complex and complementary pathways aiming to maintain protein homeostasis. These protective pathways include the unfolded protein response, the ubiquitin proteasome system, autophagy, and the encapsulation of damaged proteins in aggresomes. In this paper we review the current knowledge on the role of protein misfolding in disease and aging as well as the implication of deficiencies in the proteostasis cellular pathways in these processes. It is likely that further understanding of the mechanisms involved in protein misfolding and the natural defense pathways may lead to novel strategies for treatment of age-dependent protein misfolding disorders and perhaps aging itself.
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277
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Hernebring M, Fredriksson Å, Liljevald M, Cvijovic M, Norrman K, Wiseman J, Semb H, Nyström T. Removal of damaged proteins during ES cell fate specification requires the proteasome activator PA28. Sci Rep 2013; 3:1381. [PMID: 23459332 PMCID: PMC3587881 DOI: 10.1038/srep01381] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Accepted: 02/14/2013] [Indexed: 11/09/2022] Open
Abstract
In embryonic stem cells, removal of oxidatively damaged proteins is triggered upon the first signs of cell fate specification but the underlying mechanism is not known. Here, we report that this phase of differentiation encompasses an unexpected induction of genes encoding the proteasome activator PA28αβ (11S), subunits of the immunoproteasome (20Si), and the 20Si regulator TNFα. This induction is accompanied by assembly of mature PA28-20S(i) proteasomes and elevated proteasome activity. Inhibiting accumulation of PA28α using miRNA counteracted the removal of damaged proteins demonstrating that PA28αβ has a hitherto unidentified role required for resetting the levels of protein damage at the transition from self-renewal to cell differentiation.
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Affiliation(s)
- Malin Hernebring
- Department of Chemistry and Molecular Biology, University of Gothenburg, SE-413 90 Göteborg, Sweden.
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278
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Son MY, Seol B, Han YM, Cho YS. Comparative receptor tyrosine kinase profiling identifies a novel role for AXL in human stem cell pluripotency. Hum Mol Genet 2013; 23:1802-16. [PMID: 24218367 DOI: 10.1093/hmg/ddt571] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The extensive molecular characterization of human pluripotent stem cells (hPSCs), human embryonic stem cells (hESCs) and human-induced pluripotent stem cells (hiPSCs) is required before they can be applied in the future for personalized medicine and drug discovery. Despite the efforts that have been made with kinome analyses, we still lack in-depth insights into the molecular signatures of receptor tyrosine kinases (RTKs) that are related to pluripotency. Here, we present the first detailed and distinct repertoire of RTK characteristic for hPSC pluripotency by determining both the expression and phosphorylation profiles of RTKs in hESCs and hiPSCs using reverse transcriptase-polymerase chain reaction with degenerate primers that target conserved tyrosine kinase domains and phospho-RTK array, respectively. Among the RTKs tested, the up-regulation of EPHA1, ERBB2, FGFR4 and VEGFR2 and the down-regulation of AXL, EPHA4, PDGFRB and TYRO3 in terms of both their expression and phosphorylation levels were predominantly related to the maintenance of hPSC pluripotency. Notably, the specific inhibition of AXL was significantly advantageous in maintaining undifferentiated hESCs and hiPSCs and for the overall efficiency and kinetics of hiPSC generation. Additionally, a global phosphoproteomic analysis showed that ∼30% of the proteins (293 of 970 phosphoproteins) showed differential phosphorylation upon AXL inhibition in undifferentiated hPSCs, revealing the potential contribution of AXL-mediated phosphorylation dynamics to pluripotency-related signaling networks. Our findings provide a novel molecular signature of AXL in pluripotency control that will complement existing pluripotency-kinome networks.
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Affiliation(s)
- Mi-Young Son
- Stem Cell Research Center, KRIBB, 125 Gwahangno, Yuseong-gu, Daejeon 305-806, Republic of Korea
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279
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Qi T, Zhang W, Luan Y, Kong F, Xu D, Cheng G, Wang Y. Proteomic profiling identified multiple short-lived members of the central proteome as the direct targets of the addicted oncogenes in cancer cells. Mol Cell Proteomics 2013; 13:49-62. [PMID: 24105791 DOI: 10.1074/mcp.m113.027813] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
"Oncogene addiction" is an unexplained phenomenon in the area of cancer targeted therapy. In this study, we have tested a hypothesis that rapid apoptotic response of cancer cells following acute inhibition of the addicted oncogenes is because of loss of multiple short-lived proteins whose activity normally maintain cell survival by blocking caspase activation directly or indirectly. It was shown that rapid apoptotic response or acute apoptosis could be induced in both A431 and MiaPaCa-2 cells, and quick down-regulation of 17 proteins, which were all members of the central proteome of human cells, was found to be associated with the onset of acute apoptosis. Knockdown of PSMD11 could partially promote the occurrence of acute apoptosis in both MiaPaCa-2 and PANC-1 pancreatic cancer cells. These findings indicate that maintaining the stability of central proteome may be a primary mechanism for addicted oncogenes to maintain the survival of cancer cells through various signaling pathways, and quick loss of some of the short-lived members of the central proteome may be the direct reason for the rapid apoptotic response or acute apoptosis following acute inhibition of the addicted oncogenes in cancer cells. These findings we have presented can help us better understand the phenomenon of oncogene-addiction and may have important implications for the targeted therapy of cancer.
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Affiliation(s)
- Tonggang Qi
- Central Research Laboratory, The Second Hospital of Shandong University, Jinan, China
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280
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Förster F, Unverdorben P, Śledź P, Baumeister W. Unveiling the Long-Held Secrets of the 26S Proteasome. Structure 2013; 21:1551-62. [DOI: 10.1016/j.str.2013.08.010] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 08/15/2013] [Accepted: 08/16/2013] [Indexed: 01/23/2023]
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281
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Rafalski VA, Mancini E, Brunet A. Energy metabolism and energy-sensing pathways in mammalian embryonic and adult stem cell fate. J Cell Sci 2013; 125:5597-608. [PMID: 23420198 DOI: 10.1242/jcs.114827] [Citation(s) in RCA: 132] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Metabolism is influenced by age, food intake, and conditions such as diabetes and obesity. How do physiological or pathological metabolic changes influence stem cells, which are crucial for tissue homeostasis? This Commentary reviews recent evidence that stem cells have different metabolic demands than differentiated cells, and that the molecular mechanisms that control stem cell self-renewal and differentiation are functionally connected to the metabolic state of the cell and the surrounding stem cell niche. Furthermore, we present how energy-sensing signaling molecules and metabolism regulators are implicated in the regulation of stem cell self-renewal and differentiation. Finally, we discuss the emerging literature on the metabolism of induced pluripotent stem cells and how manipulating metabolic pathways might aid cellular reprogramming. Determining how energy metabolism regulates stem cell fate should shed light on the decline in tissue regeneration that occurs during aging and facilitate the development of therapies for degenerative or metabolic diseases.
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282
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Abstract
Mammalian aging is associated with reduced tissue regeneration, increased degenerative disease, and cancer. Because stem cells regenerate many adult tissues and contribute to the development of cancer by accumulating mutations, age-related changes in stem cells likely contribute to age-related morbidity. Consistent with this, stem cell function declines with age in numerous tissues as a result of gate-keeping tumor suppressor expression, DNA damage, changes in cellular physiology, and environmental changes in tissues. It remains unknown whether declines in stem cell function during aging influence organismal longevity. However, mechanisms that influence longevity also modulate age-related morbidity, partly through effects on stem cells.
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Affiliation(s)
- Robert A J Signer
- Children's Research Institute, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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283
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Chung S, Suzuki H, Miyamoto T, Takamatsu N, Tatsuguchi A, Ueda K, Kijima K, Nakamura Y, Matsuo Y. Development of an orally-administrative MELK-targeting inhibitor that suppresses the growth of various types of human cancer. Oncotarget 2013; 3:1629-40. [PMID: 23283305 PMCID: PMC3681500 DOI: 10.18632/oncotarget.790] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
We previously reported MELK (maternal embryonic leucine zipper kinase) as a novel therapeutic target for breast cancer. MELK was also reported to be highly upregulated in multiple types of human cancer. It was implied to play indispensable roles in cancer cell survival and indicated its involvement in the maintenance of tumor-initiating cells. We conducted a high-throughput screening of a compound library followed by structure-activity relationship studies, and successfully obtained a highly potent MELK inhibitor OTSSP167 with IC50 of 0.41 nM. OTSSP167 inhibited the phosphorylation of PSMA1 (proteasome subunit alpha type 1) and DBNL (drebrin-like), which we identified as novel MELK substrates and are important for stem-cell characteristics and invasiveness. The compound suppressed mammosphere formation of breast cancer cells and exhibited significant tumor growth suppression in xenograft studies using breast, lung, prostate, and pancreas cancer cell lines in mice by both intravenous and oral administration. This MELK inhibitor should be a promising compound possibly to suppress the growth of tumor-initiating cells and be applied for treatment of a wide range of human cancer.
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Affiliation(s)
- Suyoun Chung
- Department of Medicine and Surgery, The University of Chicago, Chicago, IL, USA
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284
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Abstract
In this issue of Cell Stem Cell, Buckley et al. (2012) show that the ubiquitin-proteasome system (UPS) regulates pluripotency in embryonic stem cells and induced pluripotent stem cells, opening the door to a better understanding at the system level of protein dynamics responsible for the maintenance and induction of pluripotency.
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285
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Webb AE, Pollina EA, Vierbuchen T, Urbán N, Ucar D, Leeman DS, Martynoga B, Sewak M, Rando TA, Guillemot F, Wernig M, Brunet A. FOXO3 shares common targets with ASCL1 genome-wide and inhibits ASCL1-dependent neurogenesis. Cell Rep 2013; 4:477-91. [PMID: 23891001 DOI: 10.1016/j.celrep.2013.06.035] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 05/11/2013] [Accepted: 06/25/2013] [Indexed: 12/16/2022] Open
Abstract
FOXO transcription factors are central regulators of longevity from worms to humans. FOXO3, the FOXO isoform associated with exceptional human longevity, preserves adult neural stem cell pools. Here, we identify FOXO3 direct targets genome-wide in primary cultures of adult neural progenitor cells (NPCs). Interestingly, FOXO3-bound sites are enriched for motifs for bHLH transcription factors, and FOXO3 shares common targets with the proneuronal bHLH transcription factor ASCL1/MASH1 in NPCs. Analysis of the chromatin landscape reveals that FOXO3 and ASCL1 are particularly enriched at the enhancers of genes involved in neurogenic pathways. Intriguingly, FOXO3 inhibits ASCL1-dependent neurogenesis in NPCs and direct neuronal conversion in fibroblasts. FOXO3 also restrains neurogenesis in vivo. Our study identifies a genome-wide interaction between the prolongevity transcription factor FOXO3 and the cell-fate determinant ASCL1 and raises the possibility that FOXO3's ability to restrain ASCL1-dependent neurogenesis may help preserve the neural stem cell pool.
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Affiliation(s)
- Ashley E Webb
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
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286
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Matilainen O, Arpalahti L, Rantanen V, Hautaniemi S, Holmberg CI. Insulin/IGF-1 signaling regulates proteasome activity through the deubiquitinating enzyme UBH-4. Cell Rep 2013; 3:1980-95. [PMID: 23770237 DOI: 10.1016/j.celrep.2013.05.012] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Revised: 04/15/2013] [Accepted: 05/08/2013] [Indexed: 12/21/2022] Open
Abstract
The proteasome plays an important role in proteostasis by carrying out controlled protein degradation in the cell. Impairments in proteasome function are associated with severe and often age-related diseases. Here, we have characterized a molecular mechanism linking insulin/IGF-1 signaling (IIS) to proteasome activity. We show that decreased IIS, which promotes proteostasis and longevity, increases proteasome activity through the FOXO transcription factor DAF-16 in C. elegans. Furthermore, we reveal that DAF-16 represses expression of the proteasome-associated deubiquitinating enzyme ubh-4, which we suggest functions as a tissue-specific proteasome inhibitor. Finally, we demonstrate that proteasome activation through downregulation of the ubh-4 human ortholog uchl5 increases degradation of proteotoxic proteins in mammalian cells. In conclusion, we have established a mechanism by which the evolutionarily conserved IIS contributes to the regulation of proteasome activity in a multicellular organism.
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Affiliation(s)
- Olli Matilainen
- Research Programs Unit, Translational Cancer Biology Program, Biomedicum Helsinki, University of Helsinki, FI-00290 Helsinki, Finland
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287
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Tsakiri EN, Sykiotis GP, Papassideri IS, Gorgoulis VG, Bohmann D, Trougakos IP. Differential regulation of proteasome functionality in reproductive vs. somatic tissues of Drosophila during aging or oxidative stress. FASEB J 2013; 27:2407-20. [PMID: 23457214 PMCID: PMC4050428 DOI: 10.1096/fj.12-221408] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 02/21/2013] [Indexed: 12/29/2022]
Abstract
Proteasome is central to proteostasis maintenance, as it degrades both normal and damaged proteins. Herein, we undertook a detailed analysis of proteasome regulation in the in vivo setting of Drosophila melanogaster. We report that a major hallmark of somatic tissues of aging flies is the gradual accumulation of ubiquitinated and carbonylated proteins; these effects correlated with a ~50% reduction of proteasome expression and catalytic activities. In contrast, gonads of aging flies were relatively free of proteome oxidative damage and maintained substantial proteasome expression levels and highly active proteasomes. Moreover, gonads of young flies were found to possess more abundant and more active proteasomes than somatic tissues. Exposure of flies to oxidants induced higher proteasome activities specifically in the gonads, which were, independently of age, more resistant than soma to oxidative challenge and, as analyses in reporter transgenic flies showed, retained functional antioxidant responses. Finally, inducible Nrf2 activation in transgenic flies promoted youthful proteasome expression levels in the aged soma, suggesting that age-dependent Nrf2 dysfunction is causative of decreasing somatic proteasome expression during aging. The higher investment in proteostasis maintenance in the gonads plausibly facilitates proteome stability across generations; it also provides evidence in support of the trade-off theories of aging.
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Affiliation(s)
- Eleni N. Tsakiri
- Department of Cell Biology and Biophysics, Faculty of Biology, University of Athens, Panepistimiopolis, Athens, Greece
| | - Gerasimos P. Sykiotis
- Division of Endocrinology, Department of Internal Medicine, University of Patras Medical School, Patras, Greece
| | - Issidora S. Papassideri
- Department of Cell Biology and Biophysics, Faculty of Biology, University of Athens, Panepistimiopolis, Athens, Greece
| | - Vassilis G. Gorgoulis
- Department of Histology and Embryology, School of Medicine, University of Athens, Athens, Greece; and
| | - Dirk Bohmann
- Department of Biomedical Genetics, University of Rochester Medical Center, Rochester, New York, USA
| | - Ioannis P. Trougakos
- Department of Cell Biology and Biophysics, Faculty of Biology, University of Athens, Panepistimiopolis, Athens, Greece
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288
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Vilchez D, Boyer L, Lutz M, Merkwirth C, Morantte I, Tse C, Spencer B, Page L, Masliah E, Berggren WT, Gage FH, Dillin A. FOXO4 is necessary for neural differentiation of human embryonic stem cells. Aging Cell 2013; 12:518-22. [PMID: 23551888 DOI: 10.1111/acel.12067] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/18/2012] [Indexed: 11/29/2022] Open
Abstract
Proteostasis is critical for maintaining cell function and proteome stability may play an important role in human embryonic stem cell (hESC) immortality. Notably, hESC populations exhibit a high assembly of active proteasomes, a key node of the proteostasis network. FOXO4, an insulin/IGF-1 responsive transcription factor, regulates proteasome activity in hESCs. We find that loss of FOXO4 reduces the potential of hESCs to differentiate into neural lineages. Therefore, FOXO4 crosses evolutionary boundaries and links hESC function to invertebrate longevity modulation.
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Affiliation(s)
- David Vilchez
- Howard Hughes Medical Institute Glenn Center for Aging Research Molecular and Cell Biology Laboratory The Salk Institute for Biological Studies 10010 North Torrey Pines RoadLa Jolla CA 92037USA
| | - Leah Boyer
- Laboratory of Genetics The Salk Institute for Biological Studies 10010 North Torrey Pines RoadLa Jolla CA 92037USA
- Biomedical Science Graduate Program School of Medicine University of California, San Diego La Jolla CA 92093USA
| | - Margaret Lutz
- Stem Cell Core The Salk Institute for Biological Studies La Jolla CA 92037 USA
| | - Carsten Merkwirth
- Howard Hughes Medical Institute Glenn Center for Aging Research Molecular and Cell Biology Laboratory The Salk Institute for Biological Studies 10010 North Torrey Pines RoadLa Jolla CA 92037USA
| | - Ianessa Morantte
- Howard Hughes Medical Institute Glenn Center for Aging Research Molecular and Cell Biology Laboratory The Salk Institute for Biological Studies 10010 North Torrey Pines RoadLa Jolla CA 92037USA
| | - Chris Tse
- Laboratory of Genetics The Salk Institute for Biological Studies 10010 North Torrey Pines RoadLa Jolla CA 92037USA
| | - Brian Spencer
- Department of Neurosciences University of California, San Diego 9500 Gilman DriveLa Jolla CA 92093USA
| | - Lesley Page
- Department of Cell Biology The Scripps Research Institute 10550 North Torrey Pines RoadLa Jolla CA 92037USA
| | - Eliezer Masliah
- Department of Neurosciences University of California, San Diego 9500 Gilman DriveLa Jolla CA 92093USA
| | | | - Fred H. Gage
- Laboratory of Genetics The Salk Institute for Biological Studies 10010 North Torrey Pines RoadLa Jolla CA 92037USA
| | - Andrew Dillin
- Howard Hughes Medical Institute Glenn Center for Aging Research Molecular and Cell Biology Laboratory The Salk Institute for Biological Studies 10010 North Torrey Pines RoadLa Jolla CA 92037USA
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289
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Arczewska KD, Tomazella GG, Lindvall JM, Kassahun H, Maglioni S, Torgovnick A, Henriksson J, Matilainen O, Marquis BJ, Nelson BC, Jaruga P, Babaie E, Holmberg CI, Bürglin TR, Ventura N, Thiede B, Nilsen H. Active transcriptomic and proteomic reprogramming in the C. elegans nucleotide excision repair mutant xpa-1. Nucleic Acids Res 2013; 41:5368-81. [PMID: 23580547 PMCID: PMC3664812 DOI: 10.1093/nar/gkt225] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Transcription-blocking oxidative DNA damage is believed to contribute to aging and to underlie activation of oxidative stress responses and down-regulation of insulin-like signaling (ILS) in Nucleotide Excision Repair (NER) deficient mice. Here, we present the first quantitative proteomic description of the Caenorhabditis elegans NER-defective xpa-1 mutant and compare the proteome and transcriptome signatures. Both methods indicated activation of oxidative stress responses, which was substantiated biochemically by a bioenergetic shift involving increased steady-state reactive oxygen species (ROS) and Adenosine triphosphate (ATP) levels. We identify the lesion-detection enzymes of Base Excision Repair (NTH-1) and global genome NER (XPC-1 and DDB-1) as upstream requirements for transcriptomic reprogramming as RNA-interference mediated depletion of these enzymes prevented up-regulation of genes over-expressed in the xpa-1 mutant. The transcription factors SKN-1 and SLR-2, but not DAF-16, were identified as effectors of reprogramming. As shown in human XPA cells, the levels of transcription-blocking 8,5'-cyclo-2'-deoxyadenosine lesions were reduced in the xpa-1 mutant compared to the wild type. Hence, accumulation of cyclopurines is unlikely to be sufficient for reprogramming. Instead, our data support a model where the lesion-detection enzymes NTH-1, XPC-1 and DDB-1 play active roles to generate a genomic stress signal sufficiently strong to result in transcriptomic reprogramming in the xpa-1 mutant.
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Affiliation(s)
- Katarzyna D Arczewska
- The Biotechnology Centre, University of Oslo, PO Box 1125 Blindern, 0317 Oslo, Norway
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290
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Tanaka K, Matsuda N. Proteostasis and neurodegeneration: the roles of proteasomal degradation and autophagy. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1843:197-204. [PMID: 23523933 DOI: 10.1016/j.bbamcr.2013.03.012] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Revised: 03/01/2013] [Accepted: 03/10/2013] [Indexed: 11/30/2022]
Abstract
All proteins in a cell continuously turn over, each at its own rate, contributing to a cell's development, differentiation, or aging. Of course, unnecessary protein(s), or those synthesized in excess, that hamper cellular homeostasis should be discarded rapidly. Furthermore, cells that have been subjected to various environmental stresses, e.g., reactive oxygen species (ROS) and UV irradiation, may incur various types of protein damage, which vitiate normal and homeostatic functions in the cell. Thereby, the prompt elimination of impaired proteins is essential for cell viability. This housekeeping is accomplished by two major catabolic routes-proteasomal digestion and autophagy. Strict maintenance of proteostasis is particularly important in non-proliferative cells, especially neurons, and it is plausible that its failure leads to a number of the neurodegenerative diseases becoming prominent in the growing elderly population. This article is part of a Special Issue entitled: Ubiquitin-Proteasome System. Guest Editors: Thomas Sommer and Dieter H. Wolf.
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Affiliation(s)
- Keiji Tanaka
- Laboratory of Protein Metabolism, Tokyo Metropolitan Institute of Medical Science, Kamikitazawa 2-1-6, Setagaya-ku, Tokyo 156-8506, Japan.
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291
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Trougakos IP, Sesti F, Tsakiri E, Gorgoulis VG. Non-enzymatic post-translational protein modifications and proteostasis network deregulation in carcinogenesis. J Proteomics 2013; 92:274-98. [PMID: 23500136 DOI: 10.1016/j.jprot.2013.02.024] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 02/19/2013] [Accepted: 02/27/2013] [Indexed: 12/25/2022]
Abstract
Organisms are constantly challenged by stressors and thus the maintenance of biomolecules functionality is essential for the assurance of cellular homeostasis. Proteins carry out the vast majority of cellular functions by mostly participating in multimeric protein assemblies that operate as protein machines. Cells have evolved a complex proteome quality control network for the rescue, when possible, or the degradation of damaged polypeptides. Nevertheless, despite these proteostasis ensuring mechanisms, new protein synthesis, and the replication-mediated dilution of proteome damage in mitotic cells, the gradual accumulation of stressors during aging (or due to lifestyle) results in increasingly damaged proteome. Non-enzymatic post-translational protein modifications mostly arise by unbalanced redox homeostasis and/or high glucose levels and may cause disruption of proteostasis as they can alter protein function. This outcome may then increase genomic instability due to reduced fidelity in processes like DNA replication or repair. Herein, we present a synopsis of the major non-enzymatic post-translation protein modifications and of the proteostasis network deregulation in carcinogenesis. We propose that activation of the proteostasis ensuring mechanisms in premalignant cells has tumor-preventive effects, whereas considering that over-activation of these mechanisms represents a hallmark of advanced tumors, their inhibition provides a strategy for the development of anti-tumor therapies. This article is part of a Special Issue entitled: Posttranslational Protein modifications in biology and Medicine.
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Affiliation(s)
- Ioannis P Trougakos
- Department of Cell Biology and Biophysics, Faculty of Biology, University of Athens, Panepistimiopolis, Athens 15784, Greece.
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292
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Guan JL, Simon AK, Prescott M, Menendez JA, Liu F, Wang F, Wang C, Wolvetang E, Vazquez-Martin A, Zhang J. Autophagy in stem cells. Autophagy 2013; 9:830-49. [PMID: 23486312 DOI: 10.4161/auto.24132] [Citation(s) in RCA: 217] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Autophagy is a highly conserved cellular process by which cytoplasmic components are sequestered in autophagosomes and delivered to lysosomes for degradation. As a major intracellular degradation and recycling pathway, autophagy is crucial for maintaining cellular homeostasis as well as remodeling during normal development, and dysfunctions in autophagy have been associated with a variety of pathologies including cancer, inflammatory bowel disease and neurodegenerative disease. Stem cells are unique in their ability to self-renew and differentiate into various cells in the body, which are important in development, tissue renewal and a range of disease processes. Therefore, it is predicted that autophagy would be crucial for the quality control mechanisms and maintenance of cellular homeostasis in various stem cells given their relatively long life in the organisms. In contrast to the extensive body of knowledge available for somatic cells, the role of autophagy in the maintenance and function of stem cells is only beginning to be revealed as a result of recent studies. Here we provide a comprehensive review of the current understanding of the mechanisms and regulation of autophagy in embryonic stem cells, several tissue stem cells (particularly hematopoietic stem cells), as well as a number of cancer stem cells. We discuss how recent studies of different knockout mice models have defined the roles of various autophagy genes and related pathways in the regulation of the maintenance, expansion and differentiation of various stem cells. We also highlight the many unanswered questions that will help to drive further research at the intersection of autophagy and stem cell biology in the near future.
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Affiliation(s)
- Jun-Lin Guan
- Division of Molecular Medicine, Department of Internal Medicine and Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA.
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293
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Diversity in the origins of proteostasis networks--a driver for protein function in evolution. Nat Rev Mol Cell Biol 2013; 14:237-48. [PMID: 23463216 DOI: 10.1038/nrm3542] [Citation(s) in RCA: 166] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Although the sequence of a protein largely determines its function, proteins can adopt different folding states in response to changes in the environment, some of which may be deleterious to the organism. All organisms--Bacteria, Archaea and Eukarya--have evolved a protein homeostasis, or proteostasis, network comprising chaperones and folding factors, degradation components, signalling pathways and specialized compartmentalized modules that manage protein folding in response to environmental stimuli and variation. Surveying the origins of proteostasis networks reveals that they have co-evolved with the proteome to regulate the physiological state of the cell, reflecting the unique stresses that different cells or organisms experience, and that they have a key role in driving evolution by closely managing the link between the phenotype and the genotype.
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294
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Tsakiri EN, Sykiotis GP, Papassideri IS, Gorgoulis VG, Bohmann D, Trougakos IP. Differential regulation of proteasome functionality in reproductive vs. somatic tissues of Drosophila during aging or oxidative stress. FASEB J 2013. [PMID: 23457214 DOI: 10.1096/fj.12–221408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Proteasome is central to proteostasis maintenance, as it degrades both normal and damaged proteins. Herein, we undertook a detailed analysis of proteasome regulation in the in vivo setting of Drosophila melanogaster. We report that a major hallmark of somatic tissues of aging flies is the gradual accumulation of ubiquitinated and carbonylated proteins; these effects correlated with a ~50% reduction of proteasome expression and catalytic activities. In contrast, gonads of aging flies were relatively free of proteome oxidative damage and maintained substantial proteasome expression levels and highly active proteasomes. Moreover, gonads of young flies were found to possess more abundant and more active proteasomes than somatic tissues. Exposure of flies to oxidants induced higher proteasome activities specifically in the gonads, which were, independently of age, more resistant than soma to oxidative challenge and, as analyses in reporter transgenic flies showed, retained functional antioxidant responses. Finally, inducible Nrf2 activation in transgenic flies promoted youthful proteasome expression levels in the aged soma, suggesting that age-dependent Nrf2 dysfunction is causative of decreasing somatic proteasome expression during aging. The higher investment in proteostasis maintenance in the gonads plausibly facilitates proteome stability across generations; it also provides evidence in support of the trade-off theories of aging.
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Affiliation(s)
- Eleni N Tsakiri
- Department of Cell Biology and Biophysics, Faculty of Biology, University of Athens, Panepistimiopolis, Athens, Greece
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295
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Sledź P, Förster F, Baumeister W. Allosteric effects in the regulation of 26S proteasome activities. J Mol Biol 2013; 425:1415-23. [PMID: 23416139 DOI: 10.1016/j.jmb.2013.01.036] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 01/30/2013] [Accepted: 01/30/2013] [Indexed: 10/27/2022]
Abstract
The 26S proteasome is the executive arm of the ubiquitin-proteasome system. This 2.5-MDa complex comprising the 20S core particle (CP) and the 19S regulatory particle (RP) is able to effectively execute its function due to a tightly regulated network of allosteric interactions. From this perspective, we summarize the current state of knowledge on these regulatory interdependencies. We classify them into the three functional layers-within the CP, within the RP, and at the CP-RP interface. In the CP, allosteric effects are thought to couple the gate opening and substrate proteolysis. Gate opening depends on events occurring in the RP-ATP hydrolysis and substrate binding. Finally, a number of processes occurring solely in the RP, like ATP hydrolysis or substrate deubiquitylation, are also proposed to be allosterically regulated. Recent advances in structural studies of 26S proteasome open up new avenues for dissecting and rationalizing the molecular basis of these regulatory networks.
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Affiliation(s)
- Paweł Sledź
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
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296
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Tsuneyoshi N, Tan EK, Sadasivam A, Poobalan Y, Sumi T, Nakatsuji N, Suemori H, Dunn NR. The SMAD2/3 corepressor SNON maintains pluripotency through selective repression of mesendodermal genes in human ES cells. Genes Dev 2013; 26:2471-6. [PMID: 23154981 DOI: 10.1101/gad.201772.112] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Activin/Nodal signaling via SMAD2/3 maintains human embryonic stem cell (hESC) pluripotency by direct transcriptional regulation of NANOG or, alternatively, induces mesoderm and definitive endoderm (DE) formation. In search of an explanation for these contrasting effects, we focused on SNON (SKIL), a potent SMAD2/3 corepressor that is expressed in hESCs but rapidly down-regulated upon differentiation. We show that SNON predominantly associates with SMAD2 at the promoters of primitive streak (PS) and early DE marker genes. Knockdown of SNON results in premature activation of PS and DE genes and loss of hESC morphology. In contrast, enforced SNON expression inhibits DE formation and diverts hESCs toward an extraembryonic fate. Thus, our findings provide novel mechanistic insight into how a single signaling pathway both regulates pluripotency and directs lineage commitment.
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Affiliation(s)
- Norihiro Tsuneyoshi
- Institute of Medical Biology, A*STAR (Agency for Science, Technology, and Research), Singapore, Singapore
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297
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Regulation of pluripotency and cellular reprogramming by the ubiquitin-proteasome system. Cell Stem Cell 2012; 11:783-98. [PMID: 23103054 DOI: 10.1016/j.stem.2012.09.011] [Citation(s) in RCA: 214] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Revised: 07/13/2012] [Accepted: 09/17/2012] [Indexed: 11/22/2022]
Abstract
Although transcriptional regulation of stem cell pluripotency and differentiation has been extensively studied, only a small number of studies have addressed the roles for posttranslational modifications in these processes. A key mechanism of posttranslational modification is ubiquitination by the ubiquitin-proteasome system (UPS). Here, using shotgun proteomics, we map the ubiquitinated protein landscape during embryonic stem cell (ESC) differentiation and induced pluripotency. Moreover, using UPS-targeted RNAi screens, we identify additional regulators of pluripotency and differentiation. We focus on two of these proteins, the deubiquitinating enzyme Psmd14 and the E3 ligase Fbxw7, and characterize their importance in ESC pluripotency and cellular reprogramming. This global characterization of the UPS as a key regulator of stem cell pluripotency opens the way for future studies that focus on specific UPS enzymes or ubiquitinated substrates.
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