301
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Ermolaeva M, Schumacher B. The innate immune system as mediator of systemic DNA damage responses. Commun Integr Biol 2013; 6:e26926. [PMID: 25210580 PMCID: PMC3922787 DOI: 10.4161/cib.26926] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 10/22/2013] [Accepted: 10/23/2013] [Indexed: 12/19/2022] Open
Abstract
DNA damage causally contributes to cancer development and tissue degeneration with aging.(1) Cellular DNA damage responses (DDR) mediate cell cycle arrest to allow time for DNA repair, or induce cellular senescence and apoptosis to eliminate damaged cells.(2) In contrast to cell-autonomous DNA damage responses, it remains less clear how organisms respond to genome instability in certain cell types and how distinct tissues interact when responding to tissue-specific DNA damage. C. elegans comprises an intriguing system to study the interaction between distinct tissues as germ cells evoke conserved DDR mechanisms, while somatic tissues are highly radio resistant.(3) (,) (4) The recent discovery of the "germline DNA damage-induced systemic stress response" (GDISR) sheds new light on non-cell autonomous responses to genome instability.(5) GDISR is mediated by ERK MAP kinase MPK-1 induced putative secreted peptides that are associated with innate immunity. The innate immune response leads to activation of the ubiquitin-proteasome-system (UPS) in somatic tissues, which confers systemic stress resistance. We discuss the role of the innate immunity in mediating systemic DNA damage responses and how UPS activity promotes endurance of somatic tissues.
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Affiliation(s)
- Maria Ermolaeva
- Institute for Genome Stability in Aging and Disease, Medical Faculty, University of Cologne; Cologne, Germany
| | - Björn Schumacher
- Institute for Genome Stability in Aging and Disease, Medical Faculty, University of Cologne; Cologne, Germany ; Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD); Institute for Genetics; University of Cologne; Cologne, Germany
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302
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Abstract
In a recent paper in Nature, Ermolaeva et al. uncover a systemic response to DNA damage in germ cells that protects somatic tissues, providing mechanistic insight into the bidirectional communication between germ line and soma.
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303
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Tsakiri EN, Sykiotis GP, Papassideri IS, Terpos E, Dimopoulos MA, Gorgoulis VG, Bohmann D, Trougakos IP. Proteasome dysfunction in Drosophila signals to an Nrf2-dependent regulatory circuit aiming to restore proteostasis and prevent premature aging. Aging Cell 2013; 12:802-13. [PMID: 23738891 DOI: 10.1111/acel.12111] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/22/2013] [Indexed: 11/30/2022] Open
Abstract
The ubiquitin-proteasome system is central to the regulation of cellular proteostasis. Nevertheless, the impact of in vivo proteasome dysfunction on the proteostasis networks and the aging processes remains poorly understood. We found that RNAi-mediated knockdown of 20S proteasome subunits in Drosophila melanogaster resulted in larval lethality. We therefore studied the molecular effects of proteasome dysfunction in adult flies by developing a model of dose-dependent pharmacological proteasome inhibition. Impaired proteasome function promoted several 'old-age' phenotypes and markedly reduced flies' lifespan. In young somatic tissues and in gonads of all ages, loss of proteasome activity induced higher expression levels and assembly rates of proteasome subunits. Proteasome dysfunction was signaled to the proteostasis network by reactive oxygen species that originated from malfunctioning mitochondria and triggered an Nrf2-dependent upregulation of the proteasome subunits. RNAi-mediated Nrf2 knockdown reduced proteasome activities, flies' resistance to stress, as well as longevity. Conversely, inducible activation of Nrf2 in transgenic flies upregulated basal proteasome expression and activity independently of age and conferred resistance to proteotoxic stress. Interestingly, prolonged Nrf2 overexpression reduced longevity, indicating that excessive activation of the proteostasis pathways can be detrimental. Our in vivo studies add new knowledge on the proteotoxic stress-related regulation of the proteostasis networks in higher metazoans. Proteasome dysfunction triggers the activation of an Nrf2-dependent tissue- and age-specific regulatory circuit aiming to adjust the cellular proteasome activity according to temporal and/or spatial proteolytic demands. Prolonged deregulation of this proteostasis circuit accelerates aging.
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Affiliation(s)
- Eleni N. Tsakiri
- Department of Cell Biology and Biophysics; Faculty of Biology; University of Athens; Panepistimiopolis; Athens 15784; Greece
| | - Gerasimos P. Sykiotis
- Division of Endocrinology; Department of Internal Medicine; University of Patras Medical School; Patras 26500; Greece
| | - Issidora S. Papassideri
- Department of Cell Biology and Biophysics; Faculty of Biology; University of Athens; Panepistimiopolis; Athens 15784; Greece
| | - Evangelos Terpos
- Department of Clinical Therapeutics; School of Medicine; University of Athens; Athens 11528; Greece
| | - Meletios A. Dimopoulos
- Department of Clinical Therapeutics; School of Medicine; University of Athens; Athens 11528; Greece
| | | | - Dirk Bohmann
- Department of Biomedical Genetics; University of Rochester Medical Center; Rochester; NY 14642; USA
| | - Ioannis P. Trougakos
- Department of Cell Biology and Biophysics; Faculty of Biology; University of Athens; Panepistimiopolis; Athens 15784; Greece
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304
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Shemesh N, Shai N, Ben-Zvi A. Germline stem cell arrest inhibits the collapse of somatic proteostasis early in Caenorhabditis elegans adulthood. Aging Cell 2013; 12:814-22. [PMID: 23734734 DOI: 10.1111/acel.12110] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/22/2013] [Indexed: 12/18/2022] Open
Abstract
All cells rely on highly conserved protein folding and clearance pathways to detect and resolve protein damage and to maintain protein homeostasis (proteostasis). Because age is associated with an imbalance in proteostasis, there is a need to understand how protein folding is regulated in a multicellular organism that undergoes aging. We have observed that the ability of Caenorhabditis elegans to maintain proteostasis declines sharply following the onset of oocyte biomass production, suggesting that a restricted protein folding capacity may be linked to the onset of reproduction. To test this hypothesis, we monitored the effects of different sterile mutations on the maintenance of proteostasis in the soma of C. elegans. We found that germline stem cell (GSC) arrest rescued protein quality control, resulting in maintenance of robust proteostasis in different somatic tissues of adult animals. We further demonstrated that GSC-dependent modulation of proteostasis requires several different signaling pathways, including hsf-1 and daf-16/kri-1/tcer-1, daf-12, daf-9, daf-36, nhr-80, and pha-4 that differentially modulate somatic quality control functions, such that each signaling pathway affects different aspects of proteostasis and cannot functionally complement the other pathways. We propose that the effect of GSCs on the collapse of proteostasis at the transition to adulthood is due to a switch mechanism that links GSC status with maintenance of somatic proteostasis via regulation of the expression and function of different quality control machineries and cellular stress responses that progressively lead to a decline in the maintenance of proteostasis in adulthood, thereby linking reproduction to the maintenance of the soma.
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Affiliation(s)
- Netta Shemesh
- Department of Life Sciences and The National Institute for Biotechnology in the Negev; Ben-Gurion University of the Negev; Beer Sheva 84105; Israel
| | - Nadav Shai
- Department of Life Sciences and The National Institute for Biotechnology in the Negev; Ben-Gurion University of the Negev; Beer Sheva 84105; Israel
| | - Anat Ben-Zvi
- Department of Life Sciences and The National Institute for Biotechnology in the Negev; Ben-Gurion University of the Negev; Beer Sheva 84105; Israel
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305
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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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306
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Schmidt M, Finley D. Regulation of proteasome activity in health and disease. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1843:13-25. [PMID: 23994620 DOI: 10.1016/j.bbamcr.2013.08.012] [Citation(s) in RCA: 328] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 08/05/2013] [Accepted: 08/07/2013] [Indexed: 12/13/2022]
Abstract
The ubiquitin-proteasome system (UPS) is the primary selective degradation system in the nuclei and cytoplasm of eukaryotic cells, required for the turnover of myriad soluble proteins. The hundreds of factors that comprise the UPS include an enzymatic cascade that tags proteins for degradation via the covalent attachment of a poly-ubiquitin chain, and a large multimeric enzyme that degrades ubiquitinated proteins, the proteasome. Protein degradation by the UPS regulates many pathways and is a crucial component of the cellular proteostasis network. Dysfunction of the ubiquitination machinery or the proteolytic activity of the proteasome is associated with numerous human diseases. In this review we discuss the contributions of the proteasome to human pathology, describe mechanisms that regulate the proteolytic capacity of the proteasome, and discuss strategies to modulate proteasome function as a therapeutic approach to ameliorate diseases associated with altered UPS function. 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)
- Marion Schmidt
- Albert Einstein College of Medicine, Department of Biochemistry, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
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307
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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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308
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Ciechanover A, Stanhill A. The complexity of recognition of ubiquitinated substrates by the 26S proteasome. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1843:86-96. [PMID: 23872423 DOI: 10.1016/j.bbamcr.2013.07.007] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 07/02/2013] [Accepted: 07/08/2013] [Indexed: 02/03/2023]
Abstract
The Ubiquitin Proteasome System (UPS) was discovered in two steps. Initially, APF-1 (ATP-dependent proteolytic Factor 1) later identified as ubiquitin (Ub), a hitherto known protein of unknown function, was found to covalently modify proteins. This modification led to degradation of the tagged protein by - at that time - an unknown protease. This was followed later by the identification of the 26S proteasome complex which is composed of a previously identified Multi Catalytic Protease (MCP) and an additional regulatory complex, as the protease that degrades Ub-tagged proteins. While Ub conjugation and proteasomal degradation are viewed as a continued process responsible for most of the regulated proteolysis in the cell, the two processes have also independent roles. In parallel and in the years that followed, the hallmark signal that links the substrate to the proteasome was identified as an internal Lys48-based polyUb chain. However, since these initial findings were described, our understanding of both ends of the process (i.e. Ub-conjugation to proteins, and their recognition and degradation), have advanced significantly. This enabled us to start bridging the ends of this continuous process which suffered until lately from limited structural data regarding the 26S proteasomal architecture and the structure and diversity of the Ub chains. These missing pieces are of great importance because the link between ubiquitination and proteasomal processing is subject to numerous regulatory steps and are found to function improperly in several pathologies. Recently, the molecular architecture of the 26S proteasome was resolved in great detail, enabling us to address mechanistic questions regarding the various molecular events that polyubiquitinated (polyUb) substrates undergo during binding and processing by the 26S proteasome. In addition, advancement in analytical and synthetic methods enables us to better understand the structure and diversity of the degradation signal. The review summarizes these recent findings and addresses the extrapolated meanings in light of previous reports. Finally, it addresses some of the still remaining questions to be solved in order to obtain a continuous mechanistic view of the events that a substrate undergoes from its initial ubiquitination to proteasomal degradation. 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)
- Aaron Ciechanover
- The David and Janet Polak Cancer and Vascular Biology Research Center, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 31096, Israel
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309
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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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310
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Abstract
Aging is characterized by a progressive loss of physiological integrity, leading to impaired function and increased vulnerability to death. This deterioration is the primary risk factor for major human pathologies, including cancer, diabetes, cardiovascular disorders, and neurodegenerative diseases. Aging research has experienced an unprecedented advance over recent years, particularly with the discovery that the rate of aging is controlled, at least to some extent, by genetic pathways and biochemical processes conserved in evolution. This Review enumerates nine tentative hallmarks that represent common denominators of aging in different organisms, with special emphasis on mammalian aging. These hallmarks are: genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication. A major challenge is to dissect the interconnectedness between the candidate hallmarks and their relative contributions to aging, with the final goal of identifying pharmaceutical targets to improve human health during aging, with minimal side effects.
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Affiliation(s)
- Carlos López-Otín
- Departamento de Bioquímica y Biología Molecular, Instituto Universitario de Oncología (IUOPA), Universidad de Oviedo, Oviedo, Spain
| | - Maria A. Blasco
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Linda Partridge
- Max Planck Institute for Biology of Ageing, Cologne, Germany
- Institute of Healthy Ageing, Department of Genetics, Evolution and Environment, University College London, London, UK
| | - Manuel Serrano
- Tumor Suppression Group, Molecular Oncology Program, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Guido Kroemer
- INSERM, U848, Villejuif, France
- Metabolomics Platform, Institut Gustave Roussy, Villejuif, France
- Centre de Recherche des Cordeliers, Paris, France
- Pôle de Biologie, Hôpital Européen Georges Pompidou, AP-HP, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Paris, France
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311
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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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312
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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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313
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Sandri M, Barberi L, Bijlsma AY, Blaauw B, Dyar KA, Milan G, Mammucari C, Meskers CGM, Pallafacchina G, Paoli A, Pion D, Roceri M, Romanello V, Serrano AL, Toniolo L, Larsson L, Maier AB, Muñoz-Cánoves P, Musarò A, Pende M, Reggiani C, Rizzuto R, Schiaffino S. Signalling pathways regulating muscle mass in ageing skeletal muscle. The role of the IGF1-Akt-mTOR-FoxO pathway. Biogerontology 2013; 14:303-23. [DOI: 10.1007/s10522-013-9432-9] [Citation(s) in RCA: 237] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 05/03/2013] [Indexed: 11/29/2022]
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314
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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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315
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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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316
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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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317
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Abstract
The proteasome refers to a collection of complexes centered on the 20S proteasome core particle (20S CP), a complex of 28 subunits that houses proteolytic sites in its hollow interior. Proteasomes are found in eukaryotes, archaea, and some eubacteria, and their activity is critical for many cellular pathways. Important recent advances include inhibitor binding studies and the structure of the immunoproteasome, whose specificity is altered by the incorporation of inducible catalytic subunits. The inherent repression of the 20S CP is relieved by the ATP-independent activators 11S and Blm10/PA200, whose structures reveal principles of proteasome mechanism. The structure of the ATP-dependent 19S regulatory particle, which mediates degradation of polyubiquitylated proteins, is being revealed by a combination of crystal or NMR structures of individual subunits and electron microscopy reconstruction of the intact complex. Other recent structural advances inform us about mechanisms of assembly and the role of conformational changes in the functional cycle.
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Affiliation(s)
- Erik Kish-Trier
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112-5650, USA
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318
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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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319
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Abstract
Forkhead box O (FOXO) transcription factors are involved in the regulation of the cell cycle, apoptosis and metabolism. In model organisms, FOXO activity also affects stem cell maintenance and lifespan as well as age-related diseases, such as cancer and diabetes. Multiple upstream pathways regulate FOXO activity through post-translational modifications and nuclear-cytoplasmic shuttling of both FOXO and its regulators. The diversity of this upstream regulation and the downstream effects of FOXOs suggest that they function as homeostasis regulators to maintain tissue homeostasis over time and coordinate a response to environmental changes, including growth factor deprivation, metabolic stress (starvation) and oxidative stress.
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320
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Abstract
Hormones play a critical role in driving major stage transitions and developmental timing events in many species. In the nematode C. elegans the steroid hormone receptor, DAF-12, works at the confluence of pathways regulating developmental timing, stage specification, and longevity. DAF-12 couples environmental and physiologic signals to life history regulation, and it is embedded in a rich architecture governing diverse processes. Here, we highlight the molecular insights, extraordinary circuitry, and signaling pathways governing life stage transitions in the worm and how they have yielded fundamental insights into steroid regulation of biological time.
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Affiliation(s)
- Adam Antebi
- Max Planck Institute for Biology of Ageing, Cologne, Germany.
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