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Shmueli MD, Sheban D, Eisenberg-Lerner A, Merbl Y. Histone degradation by the proteasome regulates chromatin and cellular plasticity. FEBS J 2021; 289:3304-3316. [PMID: 33914417 PMCID: PMC9292675 DOI: 10.1111/febs.15903] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 04/07/2021] [Accepted: 04/26/2021] [Indexed: 11/27/2022]
Abstract
Histones constitute the primary protein building blocks of the chromatin and play key roles in the dynamic control of chromatin compaction and epigenetic regulation. Histones are regulated by intricate mechanisms that alter their functionality and stability, thereby expanding the regulation of chromatin‐transacting processes. As such, histone degradation is tightly regulated to provide spatiotemporal control of cellular histone abundance. While several mechanisms have been implicated in controlling histone stability, here, we discuss proteasome‐dependent degradation of histones and the protein modifications that are associated with it. We then highlight specific cellular and physiological states that are associated with altered histone degradation by cellular proteasomes.
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Affiliation(s)
- Merav D Shmueli
- Department of Immunology, Weizmann Institute of Science, Rehovot, Israel
| | - Daoud Sheban
- Department of Immunology, Weizmann Institute of Science, Rehovot, Israel
| | | | - Yifat Merbl
- Department of Immunology, Weizmann Institute of Science, Rehovot, Israel
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2
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JANNUZZI AT, ARSLAN S, ALPERTUNGA B, KARADEMİR YILMAZ B. Proteasomal system related stress response in different cancer cell lines. CLINICAL AND EXPERIMENTAL HEALTH SCIENCES 2020. [DOI: 10.33808/clinexphealthsci.802815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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3
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Kondakova IV, Shashova EE, Sidenko EA, Astakhova TM, Zakharova LA, Sharova NP. Estrogen Receptors and Ubiquitin Proteasome System: Mutual Regulation. Biomolecules 2020; 10:biom10040500. [PMID: 32224970 PMCID: PMC7226411 DOI: 10.3390/biom10040500] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 03/21/2020] [Accepted: 03/25/2020] [Indexed: 12/11/2022] Open
Abstract
This review provides information on the structure of estrogen receptors (ERs), their localization and functions in mammalian cells. Additionally, the structure of proteasomes and mechanisms of protein ubiquitination and cleavage are described. According to the modern concept, the ubiquitin proteasome system (UPS) is involved in the regulation of the activity of ERs in several ways. First, UPS performs the ubiquitination of ERs with a change in their functional activity. Second, UPS degrades ERs and their transcriptional regulators. Third, UPS affects the expression of ER genes. In addition, the opportunity of the regulation of proteasome functioning by ERs—in particular, the expression of immune proteasomes—is discussed. Understanding the complex mechanisms underlying the regulation of ERs and proteasomes has great prospects for the development of new therapeutic agents that can make a significant contribution to the treatment of diseases associated with the impaired function of these biomolecules.
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Affiliation(s)
- Irina V. Kondakova
- Cancer Research Institute, Tomsk National Research Medical Center, Russian Academy of Sciences, 5 Kooperativny Street, 634009 Tomsk, Russia; (I.V.K.); (E.E.S.); (E.A.S.)
| | - Elena E. Shashova
- Cancer Research Institute, Tomsk National Research Medical Center, Russian Academy of Sciences, 5 Kooperativny Street, 634009 Tomsk, Russia; (I.V.K.); (E.E.S.); (E.A.S.)
| | - Evgenia A. Sidenko
- Cancer Research Institute, Tomsk National Research Medical Center, Russian Academy of Sciences, 5 Kooperativny Street, 634009 Tomsk, Russia; (I.V.K.); (E.E.S.); (E.A.S.)
| | - Tatiana M. Astakhova
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, 26 Vavilov Street, 119334 Moscow, Russia; (T.M.A.); (L.A.Z.)
| | - Liudmila A. Zakharova
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, 26 Vavilov Street, 119334 Moscow, Russia; (T.M.A.); (L.A.Z.)
| | - Natalia P. Sharova
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, 26 Vavilov Street, 119334 Moscow, Russia; (T.M.A.); (L.A.Z.)
- Correspondence: ; Tel.: +7-499-135-7674; Fax: +7-499-135-3322
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Proteasome Activation to Combat Proteotoxicity. Molecules 2019; 24:molecules24152841. [PMID: 31387243 PMCID: PMC6696185 DOI: 10.3390/molecules24152841] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 07/22/2019] [Accepted: 08/01/2019] [Indexed: 12/11/2022] Open
Abstract
Loss of proteome fidelity leads to the accumulation of non-native protein aggregates and oxidatively damaged species: hallmarks of an aged cell. These misfolded and aggregated species are often found, and suggested to be the culpable party, in numerous neurodegenerative diseases including Huntington's, Parkinson's, Amyotrophic Lateral Sclerosis (ALS), and Alzheimer's Diseases (AD). Many strategies for therapeutic intervention in proteotoxic pathologies have been put forth; one of the most promising is bolstering the efficacy of the proteasome to restore normal proteostasis. This strategy is ideal as monomeric precursors and oxidatively damaged proteins, so called "intrinsically disordered proteins" (IDPs), are targeted by the proteasome. This review will provide an overview of disorders in proteins, both intrinsic and acquired, with a focus on susceptibility to proteasomal degradation. We will then examine the proteasome with emphasis on newly published structural data and summarize current known small molecule proteasome activators.
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Aim for the core: suitability of the ubiquitin-independent 20S proteasome as a drug target in neurodegeneration. Transl Res 2018; 198:48-57. [PMID: 30244692 PMCID: PMC6154511 DOI: 10.1016/j.trsl.2018.05.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Revised: 05/14/2018] [Accepted: 05/15/2018] [Indexed: 02/06/2023]
Abstract
Neurodegenerative diseases are a class of age-associated proteopathies characterized by the accumulation of misfolded and/or aggregation-prone proteins. This imbalance has been attributed, in part, to an age-dependent decay in the capacity of protein turnover. Most proteins are degraded by the ubiquitin-proteasome system (UPS), which is composed of ubiquitin ligases and regulatory particles, such as the 19S, that deliver cargo to the proteolytically active 20S proteasome (20S) core. However, a subset of clients, especially intrinsically disordered proteins (IDPs), are also removed by the action of the ubiquitin-independent proteasome system (UIPS). What are the specific contributions of the UPS and UIPS in the context of neurodegeneration? Here, we explore how age-associated changes in the relative contribution of the UPS and UIPS, combined with the IDP-like structure of many neurodegenerative disease-associated proteins, might contribute. Strikingly, the 20S has been shown to predominate in older neurons and to preferentially act on relevant substrates, such as synuclein and tau. Moreover, pharmacological activation of the 20S has been shown to accelerate removal of aggregation-prone proteins in some models. Together, these recent studies are turning attention to the 20S and the UIPS as potential therapeutic targets in neurodegeneration.
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Alghamdi A, Vallortigara J, Howlett DR, Broadstock M, Hortobágyi T, Ballard C, Thomas AJ, O'Brien JT, Aarsland D, Attems J, Francis PT, Whitfield DR. Reduction of RPT6/S8 (a Proteasome Component) and Proteasome Activity in the Cortex is Associated with Cognitive Impairment in Lewy Body Dementia. J Alzheimers Dis 2018; 57:373-386. [PMID: 28269775 PMCID: PMC5438478 DOI: 10.3233/jad-160946] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Lewy body dementia is the second most common neurodegenerative dementia and is pathologically characterized by α-synuclein positive cytoplasmic inclusions, with varying amounts of amyloid-β (Aβ) and hyperphosphorylated tau (tau) aggregates in addition to synaptic loss. A dysfunctional ubiquitin proteasome system (UPS), the major proteolytic pathway responsible for the clearance of short lived proteins, may be a mediating factor of disease progression and of the development of α-synuclein aggregates. In the present study, protein expression of a key component of the UPS, the RPT6 subunit of the 19S regulatory complex was determined. Furthermore, the main proteolytic-like (chymotrypsin- and PGPH-) activities have also been analyzed. The middle frontal (Brodmann, BA9), inferior parietal (BA40), and anterior cingulate (BA24) gyrus' cortex were selected as regions of interest from Parkinson's disease dementia (PDD, n = 31), dementia with Lewy bodies (DLB, n = 44), Alzheimer's disease (AD, n = 16), and control (n = 24) brains. Clinical and pathological data available included the MMSE score. DLB, PDD, and AD were characterized by significant reductions of RPT6 (one-way ANOVA, p < 0.001; Bonferroni post hoc test) in prefrontal cortex and parietal cortex compared with controls. Strong associations were observed between RPT6 levels in prefrontal, parietal cortex, and anterior cingulate gyrus and cognitive impairment (p = 0.001, p = 0.001, and p = 0.008, respectively). These findings highlight the involvement of the UPS in Lewy body dementia and indicate that targeting the UPS may have the potential to slow down or reduce the progression of cognitive impairment in DLB and PDD.
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Affiliation(s)
- Amani Alghamdi
- King's College London, Wolfson Centre for Age-Related Diseases, London, UK.,Department of Biochemistry, King Saud University, College of Science, Riyadh, Saudi Arabia
| | - Julie Vallortigara
- King's College London, Wolfson Centre for Age-Related Diseases, London, UK
| | - David R Howlett
- King's College London, Wolfson Centre for Age-Related Diseases, London, UK
| | - Martin Broadstock
- King's College London, Wolfson Centre for Age-Related Diseases, London, UK
| | - Tibor Hortobágyi
- Department of Neuropathology, Institute of Pathology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Clive Ballard
- King's College London, Wolfson Centre for Age-Related Diseases, London, UK.,University of Exeter Medical School, University of Exeter, Devon, UK
| | - Alan J Thomas
- NIHR Biomedical Research Centre for Mental Health, South London and Maudsley NHS Foundation Trust and Institute of Psychiatry, Kings College London, UK
| | | | - Dag Aarsland
- Department of Neurobiology, Ward Sciences and Society, Karolinska Institute, Stockholm Sweden.,Centre for Age-Related Medicine, Stavanger University Hospital, Stavanger, Norway
| | - Johannes Attems
- Institute of Neuroscience and Newcastle University Institute for Ageing, Campus for Ageing and Vitality, UK
| | - Paul T Francis
- King's College London, Wolfson Centre for Age-Related Diseases, London, UK
| | - David R Whitfield
- King's College London, Wolfson Centre for Age-Related Diseases, London, UK
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Bottje WG, Lassiter K, Piekarski-Welsher A, Dridi S, Reverter A, Hudson NJ, Kong BW. Proteogenomics Reveals Enriched Ribosome Assembly and Protein Translation in Pectoralis major of High Feed Efficiency Pedigree Broiler Males. Front Physiol 2017; 8:306. [PMID: 28559853 PMCID: PMC5432614 DOI: 10.3389/fphys.2017.00306] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 04/27/2017] [Indexed: 12/15/2022] Open
Abstract
Background: In production animal agriculture, the cost of feed represents 60–70% of the total cost of raising an animal to market weight. Thus, development of viable biomarkers for feed efficiency (FE, g gain/g feed) to assist in genetic selection of breeding stock remains an important goal in commercial breeding programs. Methods: Global gene (cDNA microarray, RNAseq) and protein expression (shotgun proteomics) analyses have been conducted on breast muscle samples obtained from pedigree broiler males (PedM) exhibiting high and low FE phenotypes. Using the entire datasets (i.e., no cutoffs for significance or fold difference in expression) the number of genes or proteins that were expressed numerically higher or lower in the high FE compared to the low FE phenotype for key terms or functions, e.g., ribosomal, mitochondrial ribosomal, tRNA, RNA binding motif, RNA polymerase, small nuclear ribonucleoprotein, and protein tyrosine phosphatase, were determined. Bionomial distribution analysis (exact) was then conducted on these datasets to determine significance between numerically up or down expression. Results: Processes associated with mitochondrial proteome expression (e.g., mitochondrial ribosomal proteins, mitochondrial transcription, mitochondrial tRNA, and translation) were enriched in breast muscle from the high FE compared to the low FE pedigree male broiler phenotype. Furthermore, the high FE phenotype exhibited enrichment of ribosome assembly (e.g., RNA polymerase, mitochondrial and cytosolic ribosomes, small, and heterogeneous nuclear ribonucleoproteins), as well as nuclear transport and protein translation processes compared to the low FE phenotype. Quality control processes (proteosomes and autophagy) were also enriched in the high FE phenotype. In contrast, the low FE phenotype exhibited enrichment of cytoskeletal proteins, protein tyrosine phosphatases, and tyrosine kinases compared to the high FE phenotype. These results suggest that processes of mitochondrial and cytosolic ribosomal construction, activity, and protein translation would be enhanced in high FE breast muscle, and that phosphorylation of tyrosine moieties of proteins could be prolonged in the high compared to low FE phenotype. The results indicate the presence of a proteogenomic architecture that could enhance ribosome construction, protein translation, and quality control processes and contribute to the phenotypic expression of feed efficiency in this PedM broiler model.
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Affiliation(s)
- Walter G Bottje
- Department of Poultry Science, Center of Excellence for Poultry Science, University of ArkansasFayetteville, AR, USA
| | - Kentu Lassiter
- Department of Poultry Science, Center of Excellence for Poultry Science, University of ArkansasFayetteville, AR, USA
| | - Alissa Piekarski-Welsher
- Department of Poultry Science, Center of Excellence for Poultry Science, University of ArkansasFayetteville, AR, USA
| | - Sami Dridi
- Department of Poultry Science, Center of Excellence for Poultry Science, University of ArkansasFayetteville, AR, USA
| | - Antonio Reverter
- Computational and Systems Biology, Agriculture and Food (CSIRO)St. Lucia, QLD, Australia
| | - Nicholas J Hudson
- Animal Science, School of Agriculture and Food Science, University of QueenslandGatton, QLD, Australia
| | - Byung-Whi Kong
- Department of Poultry Science, Center of Excellence for Poultry Science, University of ArkansasFayetteville, AR, USA
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Yu D, Li X, Zhao X, Du C, Chen J, Li C, Sun M, Wang L, Lin J, Tang D, Yu F, Liu X. RPN1a negatively regulates ABA signaling in Arabidopsis. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2016; 108:279-285. [PMID: 27474935 DOI: 10.1016/j.plaphy.2016.06.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 06/01/2016] [Accepted: 06/11/2016] [Indexed: 06/06/2023]
Abstract
The 26S proteasome selectively regulates key abscisic acid (ABA) signaling proteins, but the physiological functions and mechanisms of RPN1a (a subunit of the 26S proteasome) in ABA signaling remain largely unknown. In this study, we found that the mRNA expression of RPN1a was suppressed by ABA treatment, and that RPN1a protein was expressed abundantly in guard cells. In the presence of ABA, rpn1a mutants showed rapid stomatal closure, low water loss, delayed germination, and inhibited root elongation. In addition, the transcripts of key ABA signaling genes, including ABI5, RD22, RD29A, and RD29B, were upregulated in rpn1a mutant plants in response to ABA. Furthermore, the ABI5 protein level was higher in rpn1a mutants subjected to ABA treatment. Yeast two-hybrid and bimolecular fluorescence complementation assays showed that RPN1a interacts with ABI1. Overall, these findings suggest that RPN1a negatively regulates ABA signaling in Arabidopsis.
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Affiliation(s)
- Dashi Yu
- Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, China
| | - Xiushan Li
- Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, China
| | - Xiaoying Zhao
- Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, China
| | - Changqing Du
- Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, China
| | - Jia Chen
- Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, China
| | - Chiyu Li
- Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, China
| | - Mengsi Sun
- Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, China
| | - Long Wang
- Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, China
| | - Jianzhong Lin
- Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, China
| | - Dongying Tang
- Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, China
| | - Feng Yu
- Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, China.
| | - Xuanming Liu
- Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410082, China; State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha, 410082, China.
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9
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Maganti N, Moody TD, Truax AD, Thakkar M, Spring AM, Germann MW, Greer SF. Nonproteolytic roles of 19S ATPases in transcription of CIITApIV genes. PLoS One 2014; 9:e91200. [PMID: 24625964 PMCID: PMC3953376 DOI: 10.1371/journal.pone.0091200] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 02/11/2014] [Indexed: 11/19/2022] Open
Abstract
Accumulating evidence shows the 26S proteasome is involved in the regulation of gene expression. We and others have demonstrated that proteasome components bind to sites of gene transcription, regulate covalent modifications to histones, and are involved in the assembly of activator complexes in mammalian cells. The mechanisms by which the proteasome influences transcription remain unclear, although prior observations suggest both proteolytic and non-proteolytic activities. Here, we define novel, non-proteolytic, roles for each of the three 19S heterodimers, represented by the 19S ATPases Sug1, S7, and S6a, in mammalian gene expression using the inflammatory gene CIITApIV. These 19S ATPases are recruited to induced CIITApIV promoters and also associate with CIITA coding regions. Additionally, these ATPases interact with elongation factor PTEFb complex members CDK9 and Hexim-1 and with Ser5 phosphorylated RNA Pol II. Both the generation of transcripts from CIITApIV and efficient recruitment of RNA Pol II to CIITApIV are negatively impacted by siRNA mediated knockdown of these 19S ATPases. Together, these results define novel roles for 19S ATPases in mammalian gene expression and indicate roles for these ATPases in promoting transcription processes.
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Affiliation(s)
- Nagini Maganti
- Graduate Program in Cell Biology and Immunology, Department of Biology, Georgia State University, Atlanta, Georgia, United States of America
| | - Tomika D. Moody
- Graduate Program in Cell Biology and Immunology, Department of Biology, Georgia State University, Atlanta, Georgia, United States of America
| | - Agnieszka D. Truax
- Graduate Program in Cell Biology and Immunology, Department of Biology, Georgia State University, Atlanta, Georgia, United States of America
| | - Meghna Thakkar
- Graduate Program in Cell Biology and Immunology, Department of Biology, Georgia State University, Atlanta, Georgia, United States of America
| | - Alexander M. Spring
- Department of Chemistry, Georgia State University, Atlanta, Georgia, United States of America
| | - Markus W. Germann
- Department of Chemistry, Georgia State University, Atlanta, Georgia, United States of America
| | - Susanna F. Greer
- Graduate Program in Cell Biology and Immunology, Department of Biology, Georgia State University, Atlanta, Georgia, United States of America
- * E-mail:
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Wang X, Guerrero C, Kaiser P, Huang L. Proteomics of proteasome complexes and ubiquitinated proteins. Expert Rev Proteomics 2014; 4:649-65. [DOI: 10.1586/14789450.4.5.649] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Abstract
The ubiquitin-mediated degradation of proteins in numerous cellular processes, such as turnover and quality control of proteins, cell cycle and apoptosis, transcription and cell signaling, immune response and antigen presentation, and inflammation and development makes the ubiquitin-proteosome systems a very interesting target for various therapeutic interventions. Proteosome inhibitors were first synthesized as tools to probe the function and specificity of this particle's proteolytic activities. Most synthetic inhibitors rely on a peptide base, which mimics a protein substrate, attached at a COOH terminal "warhead." Notable warheads include boronic acids, such as bortezomib and epoxy ketones, such as carfilzomib. A variety of natural products also inhibit the proteosome that are not peptide-based, most notably lactacystin, that is related to NPI-0052, or salinosporamide A, another inhibitor in clinical trials. The possibility that proteosome inhibitors could be drug candidates was considered after studies showed that they induced apoptosis in leukemic cell lines. The first proteasome inhibitor in clinical application, bortezomib showed activity in non-small-cell lung and androgen-independent prostate carcinoma, as well as MM and mantle cell and follicular non-Hodgkin's lymphoma. It is now licensed for the treatment of newly diagnosed as well as relapsed/progressive MM and has had a major impact on the improvement in the treatment of MM in the last few years.
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Affiliation(s)
- Hermann Einsele
- Department of Internal Medicine II, University Hospital Würzburg, Josef-Schneider Straße 2, 97080, Wurzburg, Germany,
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12
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A novel interplay between the ubiquitin–proteasome system and serine proteases during Drosophila development. Biochem J 2013; 454:571-83. [PMID: 23805892 DOI: 10.1042/bj20130040] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 06/26/2013] [Accepted: 06/28/2013] [Indexed: 11/17/2022]
Abstract
The concentrations of the Drosophila proteasomal and extraproteasomal polyubiquitin receptors fluctuate in a developmentally regulated fashion. This fluctuation is generated by a previously unidentified proteolytic activity. In the present paper, we describe the purification, identification and characterization of this protease (endoproteinase I). Its expression increases sharply at the L1-L2 larval stages, remains high until the second half of the L3 stage, then declines dramatically. This sharp decrease coincides precisely with the increase of polyubiquitin receptor concentrations in late L3 larvae, which suggests a tight developmental co-regulation. RNAi-induced down-regulation of endoproteinase I results in pupal lethality. Interestingly, we found a cross-talk between the 26S proteasome and this larval protease: transgenic overexpression of the in vivo target of endoproteinase I, the C-terminal half of the proteasomal polyubiquitin receptor subunit p54/Rpn10 results in transcriptional down-regulation of endoproteinase I and consequently a lower level of proteolytic elimination of the polyubiquitin receptors. Another larval protease, Jonah65A-IV, which degrades only unfolded proteins and exhibits similar cross-talk with the proteasome has also been purified and characterized. It may prevent the accumulation of polyubiquitylated proteins in larvae contrary to the low polyubiquitin receptor concentration.
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13
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Separation of a functional deubiquitylating module from the SAGA complex by the proteasome regulatory particle. Nat Commun 2013; 4:2641. [DOI: 10.1038/ncomms3641] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 09/19/2013] [Indexed: 01/01/2023] Open
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Abstract
The plant cytotoxin ricin enters mammalian cells by receptor-mediated endocytosis, undergoing retrograde transport to the ER (endoplasmic reticulum) where its catalytic A chain (RTA) is reductively separated from the holotoxin to enter the cytosol and inactivate ribosomes. The currently accepted model is that the bulk of ER-dislocated RTA is degraded by proteasomes. We show in the present study that the proteasome has a more complex role in ricin intoxication than previously recognized, that the previously reported increase in sensitivity of mammalian cells to ricin in the presence of proteasome inhibitors simply reflects toxicity of the inhibitors themselves, and that RTA is a very poor substrate for proteasomal degradation. Denatured RTA and casein compete for a binding site on the regulatory particle of the 26S proteasome, but their fates differ. Casein is degraded, but the mammalian 26S proteasome AAA (ATPase associated with various cellular activities)-ATPase subunit RPT5 acts as a chaperone that prevents aggregation of denatured RTA and stimulates recovery of catalytic RTA activity in vitro. Furthermore, in vivo, the ATPase activity of Rpt5p is required for maximal toxicity of RTA dislocated from the Saccharomyces cerevisiae ER. The results of the present study implicate RPT5/Rpt5p in the triage of substrates in which either activation (folding) or inactivation (degradation) pathways may be initiated.
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15
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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: 318] [Impact Index Per Article: 28.9] [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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16
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Leone P, Shin EC, Perosa F, Vacca A, Dammacco F, Racanelli V. MHC class I antigen processing and presenting machinery: organization, function, and defects in tumor cells. J Natl Cancer Inst 2013; 105:1172-87. [PMID: 23852952 DOI: 10.1093/jnci/djt184] [Citation(s) in RCA: 362] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The surface presentation of peptides by major histocompatibility complex (MHC) class I molecules is critical to all CD8(+) T-cell adaptive immune responses, including those against tumors. The generation of peptides and their loading on MHC class I molecules is a multistep process involving multiple molecular species that constitute the so-called antigen processing and presenting machinery (APM). The majority of class I peptides begin as proteasome degradation products of cytosolic proteins. Once transported into the endoplasmic reticulum by TAP (transporter associated with antigen processing), peptides are not bound randomly by class I molecules but are chosen by length and sequence, with peptidases editing the raw peptide pool. Aberrations in APM genes and proteins have frequently been observed in human tumors and found to correlate with relevant clinical variables, including tumor grade, tumor stage, disease recurrence, and survival. These findings support the idea that APM defects are immune escape mechanisms that disrupt the tumor cells' ability to be recognized and killed by tumor antigen-specific cytotoxic CD8(+) T cells. Detailed knowledge of APM is crucial for the optimization of T cell-based immunotherapy protocols.
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Affiliation(s)
- Patrizia Leone
- Department of Internal Medicine and Clinical Oncology, University of Bari Medical School, Bari, Italy
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Dechavanne V, Vilbois F, Glez L, Antonsson B. Purification and separation of the 20S immunoproteasome from the constitutive proteasome and identification of the subunits by LC–MS. Protein Expr Purif 2013; 87:100-10. [DOI: 10.1016/j.pep.2012.10.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 10/29/2012] [Accepted: 10/31/2012] [Indexed: 10/27/2022]
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18
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Campello L, Esteve-Rudd J, Cuenca N, Martín-Nieto J. The ubiquitin-proteasome system in retinal health and disease. Mol Neurobiol 2013; 47:790-810. [PMID: 23339020 DOI: 10.1007/s12035-012-8391-5] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 12/18/2012] [Indexed: 10/27/2022]
Abstract
The ubiquitin-proteasome system (UPS) is the main intracellular pathway for modulated protein turnover, playing an important role in the maintenance of cellular homeostasis. It also exerts a protein quality control through degradation of oxidized, mutant, denatured, or misfolded proteins and is involved in many biological processes where protein level regulation is necessary. This system allows the cell to modulate its protein expression pattern in response to changing physiological conditions and provides a critical protective role in health and disease. Impairments of UPS function in the central nervous system (CNS) underlie an increasing number of genetic and idiopathic diseases, many of which affect the retina. Current knowledge on the UPS composition and function in this tissue, however, is scarce and dispersed. This review focuses on UPS elements reported in the retina, including ubiquitinating and deubiquitinating enzymes (DUBs), and alternative proteasome assemblies. Known and inferred roles of protein ubiquitination, and of the related, SUMO conjugation (SUMOylation) process, in normal retinal development and adult homeostasis are addressed, including modulation of the visual cycle and response to retinal stress and injury. Additionally, the relationship between UPS dysfunction and human neurodegenerative disorders affecting the retina, including Alzheimer's, Parkinson's, and Huntington's diseases, are dealt with, together with numerous instances of retina-specific illnesses with UPS involvement, such as retinitis pigmentosa, macular degenerations, glaucoma, diabetic retinopathy (DR), and aging-related impairments. This information, though still basic and limited, constitutes a suitable framework to be expanded in incoming years and should prove orientative toward future therapy design targeting sight-affecting diseases with a UPS underlying basis.
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Affiliation(s)
- Laura Campello
- Departamento de Fisiología, Genética y Microbiología, Facultad de Ciencias, Universidad de Alicante, 03080 Alicante, Spain
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19
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Höhn A, König J, Grune T. Protein oxidation in aging and the removal of oxidized proteins. J Proteomics 2013; 92:132-59. [PMID: 23333925 DOI: 10.1016/j.jprot.2013.01.004] [Citation(s) in RCA: 154] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 01/08/2013] [Indexed: 12/12/2022]
Abstract
Reactive oxygen species (ROS) are generated constantly within cells at low concentrations even under physiological conditions. During aging the levels of ROS can increase due to a limited capacity of antioxidant systems and repair mechanisms. Proteins are among the main targets for oxidants due to their high rate constants for several reactions with ROS and their abundance in biological systems. Protein damage has an important influence on cellular viability since most protein damage is non-repairable, and has deleterious consequences on protein structure and function. In addition, damaged and modified proteins can form cross-links and provide a basis for many senescence-associated alterations and may contribute to a range of human pathologies. Two proteolytic systems are responsible to ensure the maintenance of cellular functions: the proteasomal (UPS) and the lysosomal system. Those degrading systems provide a last line of antioxidative protection, removing irreversible damaged proteins and recycling amino acids for the continuous protein synthesis. But during aging, both systems are affected and their proteolytic activity declines significantly. Here we highlight the recent advantages in the understanding of protein oxidation and the fate of these damaged proteins during aging. This article is part of a Special Issue entitled: Posttranslational Protein modifications in biology and Medicine.
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Affiliation(s)
- Annika Höhn
- Department of Nutritional Toxicology, Institute of Nutrition, Friedrich Schiller University Jena, 07743 Jena, Germany
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20
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Penney M, Samejima I, Wilkinson CR, McInerny CJ, Mathiassen SG, Wallace M, Toda T, Hartmann-Petersen R, Gordon C. Fission yeast 26S proteasome mutants are multi-drug resistant due to stabilization of the Pap1 transcription factor. PLoS One 2012; 7:e50796. [PMID: 23209828 PMCID: PMC3507774 DOI: 10.1371/journal.pone.0050796] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 10/25/2012] [Indexed: 01/12/2023] Open
Abstract
Here we report the result of a genetic screen for mutants resistant to the microtubule poison methyl benzimidazol-2-yl carbamate (MBC) that were also temperature sensitive for growth. In total the isolated mutants were distributed in ten complementation groups. Cloning experiments revealed that most of the mutants were in essential genes encoding various 26S proteasome subunits. We found that the proteasome mutants are multi-drug resistant due to stabilization of the stress-activated transcription factor Pap1. We show that the ubiquitylation and ultimately the degradation of Pap1 depend on the Rhp6/Ubc2 E2 ubiquitin conjugating enzyme and the Ubr1 E3 ubiquitin-protein ligase. Accordingly, mutants lacking Rhp6 or Ubr1 display drug-resistant phenotypes.
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Affiliation(s)
- Mary Penney
- Medical Research Council, Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
| | - Itaru Samejima
- Medical Research Council, Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
| | - Caroline R. Wilkinson
- Cell Regulation Group, Paterson Institute for Cancer Research, University of Manchester, Manchester, United Kingdom
| | - Christopher J. McInerny
- Division of Molecular and Cellular Biology, School of Life Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Søs G. Mathiassen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Mairi Wallace
- Medical Research Council, Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
| | - Takashi Toda
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, London, United Kingdom
| | | | - Colin Gordon
- Medical Research Council, Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
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21
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Adaptive response, evidence of cross-resistance and its potential clinical use. Int J Mol Sci 2012; 13:10771-10806. [PMID: 23109822 PMCID: PMC3472714 DOI: 10.3390/ijms130910771] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 08/07/2012] [Accepted: 08/13/2012] [Indexed: 12/15/2022] Open
Abstract
Organisms and their cells are constantly exposed to environmental fluctuations. Among them are stressors, which can induce macromolecular damage that exceeds a set threshold, independent of the underlying cause. Stress responses are mechanisms used by organisms to adapt to and overcome stress stimuli. Different stressors or different intensities of stress trigger different cellular responses, namely induce cell repair mechanisms, induce cell responses that result in temporary adaptation to some stressors, induce autophagy or trigger cell death. Studies have reported life-prolonging effects of a wide variety of so-called stressors, such as oxidants, heat shock, some phytochemicals, ischemia, exercise and dietary energy restriction, hypergravity, etc. These stress responses, which result in enhanced defense and repair and even cross-resistance against multiple stressors, may have clinical use and will be discussed, while the emphasis will be on the effects/cross-effects of oxidants.
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22
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Shang F, Taylor A. Roles for the ubiquitin-proteasome pathway in protein quality control and signaling in the retina: implications in the pathogenesis of age-related macular degeneration. Mol Aspects Med 2012; 33:446-66. [PMID: 22521794 PMCID: PMC3417153 DOI: 10.1016/j.mam.2012.04.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 04/05/2012] [Indexed: 10/28/2022]
Abstract
The accumulation of damaged or postsynthetically modified proteins and dysregulation of inflammatory responses and angiogenesis in the retina/RPE are thought be etiologically related to formation of drusen and choroidal neovascularization (CNV), hallmarks of age-related macular degeneration (AMD). The ubiquitin-proteasome pathway (UPP) plays crucial roles in protein quality control, cell cycle control and signal transduction. Selective degradation of aberrant proteins by the UPP is essential for timely removal of potentially cytotoxic damaged or otherwise abnormal proteins. Proper function of the UPP is thought to be required for cellular function. In contrast, age--or stress induced--impairment the UPP or insufficient UPP capacity may contribute to the accumulation of abnormal proteins, cytotoxicity in the retina, and AMD. Crucial roles for the UPP in eye development, regulation of signal transduction, and antioxidant responses are also established. Insufficient UPP capacity in retina and RPE can result in dysregulation of signal transduction, abnormal inflammatory responses and CNV. There are also interactions between the UPP and lysosomal proteolytic pathways (LPPs). Means that modulate the proteolytic capacity are making their way into new generation of pharmacotherapies for delaying age-related diseases and may augment the benefits of adequate nutrition, with regard to diminishing the burden of AMD.
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Affiliation(s)
- Fu Shang
- Laboratory for Nutrition and Vision Research, USDA Human Nutrition Research Center on Aging, Boston, MA 02111, USA.
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23
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Camargo ACM, Fernandes BL, Cruz L, Ferro ES. Bioactive Peptides Produced by Limited Proteolysis. ACTA ACUST UNITED AC 2012. [DOI: 10.4199/c00056ed1v01y201204npe002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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24
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Lipinszki Z, Kovács L, Deák P, Udvardy A. Ubiquitylation of Drosophila p54/Rpn10/S5a Regulates Its Interaction with the UBA–UBL Polyubiquitin Receptors. Biochemistry 2012; 51:2461-70. [DOI: 10.1021/bi3001006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zoltán Lipinszki
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, H-6701 Szeged, P.O. Box 521, Hungary
| | - Levente Kovács
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, H-6701 Szeged, P.O. Box 521, Hungary
| | - Péter Deák
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, H-6701 Szeged, P.O. Box 521, Hungary
| | - Andor Udvardy
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, H-6701 Szeged, P.O. Box 521, Hungary
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25
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Lyzenga WJ, Stone SL. Abiotic stress tolerance mediated by protein ubiquitination. JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:599-616. [PMID: 22016431 DOI: 10.1093/jxb/err310] [Citation(s) in RCA: 257] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Plant growth and development is largely influenced by ubiquitin-mediated regulation of protein stability. Specificity of the ubiquitination pathway is controlled mainly by the substrate-recruiting E3 ubiquitin ligases, and consequently, E3 ligases control numerous cellular processes. Recent evidence that ubiquitination plays a critical role in regulating plant responses to abiotic stresses has launched intensive efforts to identify E3 ligases that mediate plant tolerance of adverse environmental conditions. Most stress-related E3 ligases identified to date facilitate responses to environmental stimuli by modulating the abundance of key downstream stress-responsive transcription factors. In this review, the regulatory roles of ubiquitin during the plant's response to abiotic stress are summarized and highlighted.
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Affiliation(s)
- Wendy J Lyzenga
- Department of Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
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26
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Abstract
The ubiquitin-proteasomal system is an essential element of the protein quality control machinery in cells. The central part of this system is the 20S proteasome. The proteasome is a barrel-shaped multienzyme complex, containing several active centers hidden at the inner surface of the hollow cylinder. So, the regulation of the substrate entry toward the inner proteasomal surface is a key control mechanism of the activity of this protease. This chapter outlines the knowledge on the structure of the subunits of the 20S proteasome, the binding and structure of some proteasomal regulators and inducible proteasomal subunits. Therefore, this chapter imparts the knowledge on proteasomal structure which is required for the understanding of the following chapters.
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27
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Kriegenburg F, Poulsen EG, Koch A, Krüger E, Hartmann-Petersen R. Redox control of the ubiquitin-proteasome system: from molecular mechanisms to functional significance. Antioxid Redox Signal 2011; 15:2265-99. [PMID: 21314436 DOI: 10.1089/ars.2010.3590] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In their natural environments, cells are regularly exposed to oxidizing conditions that may lead to protein misfolding. If such misfolded proteins are allowed to linger, they may form insoluble aggregates and pose a serious threat to the cell. Accumulation of misfolded, oxidatively damaged proteins is characteristic of many diseases and during aging. To counter the adverse effects of oxidative stress, cells can initiate an antioxidative response in an attempt to repair the damage, or rapidly channel the damaged proteins for degradation by the ubiquitin-proteasome system (UPS). Recent studies have shown that elements of the oxidative stress response and the UPS are linked on many levels. To manage the extra burden of misfolded proteins, the UPS is induced by oxidative stress, and special proteasome subtypes protect cells against oxidative damage. In addition, the proteasome is directly associated with a thioredoxin and other cofactors that may adjust the particle's response during an oxidative challenge. Here, we give an overview of the UPS and a detailed description of the degradation of oxidized proteins and of the crosstalk between oxidative stress and protein degradation in health and disease.
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Affiliation(s)
- Franziska Kriegenburg
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5,Copenhagen, Denmark
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28
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Melo SP, Barbour KW, Berger FG. Cooperation between an intrinsically disordered region and a helical segment is required for ubiquitin-independent degradation by the proteasome. J Biol Chem 2011; 286:36559-67. [PMID: 21878626 DOI: 10.1074/jbc.m111.274258] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The 26 S proteasomal complex, which is responsible for the bulk of protein degradation within the cell, recognizes its target substrates via covalently linked polyubiquitin moieties. However, a small but growing number of proteasomal substrates are degraded without a requirement for ubiquitinylation. One such substrate is the pyrimidine biosynthetic enzyme thymidylate synthase (EC 2.1.1.45), which catalyzes the synthesis of TMP and is the sole de novo source of TTP for DNA replication and repair. Previous work showed that intracellular proteolysis of human thymidylate synthase is directed by a degron at the polypeptide's N-terminal end, composed of an intrinsically disordered region (IDR) followed by a highly conserved amphipathic α-helix (hA). In the present report, we show that the hA helix does not function simply as an extension or scaffold for the IDR; rather, it provides a specific structural component that is necessary for degradation. Furthermore, its helical conformation is required for this function. We demonstrate that small domains from heterologous proteins can substitute for the IDR and the hA helix of human thymidylate synthase, indicating that the degradation-promoting function of these regions is not sequence-specific. The results, in general, indicate that cooperation between intrinsically disordered domains and α-helical segments is required for ubiquitin-independent degradation by the proteasome. There appears to be little sequence constraint on the ability of these regions to function as degron constituents. Rather, it is the overall conformation (or lack thereof) that is critical.
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Affiliation(s)
- Sandra P Melo
- Department of Biological Sciences and Center for Colon Cancer Research, University of South Carolina, Columbia, South Carolina 29208, USA
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29
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Shang F, Taylor A. Ubiquitin-proteasome pathway and cellular responses to oxidative stress. Free Radic Biol Med 2011; 51:5-16. [PMID: 21530648 PMCID: PMC3109097 DOI: 10.1016/j.freeradbiomed.2011.03.031] [Citation(s) in RCA: 305] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2009] [Revised: 03/08/2011] [Accepted: 03/26/2011] [Indexed: 12/13/2022]
Abstract
The ubiquitin-proteasome pathway (UPP) is the primary cytosolic proteolytic machinery for the selective degradation of various forms of damaged proteins. Thus, the UPP is an important protein quality control mechanism. In the canonical UPP, both ubiquitin and the 26S proteasome are involved. Substrate proteins of the canonical UPP are first tagged by multiple ubiquitin molecules and then degraded by the 26S proteasome. However, in noncanonical UPP, proteins can be degraded by the 26S or the 20S proteasome without being ubiquitinated. It is clear that a proteasome is responsible for selective degradation of oxidized proteins, but the extent to which ubiquitination is involved in this process remains a subject of debate. Whereas many publications suggest that the 20S proteasome degrades oxidized proteins independent of ubiquitin, there is also solid evidence indicating that ubiquitin and ubiquitination are involved in degradation of some forms of oxidized proteins. A fully functional UPP is required for cells to cope with oxidative stress and the activity of the UPP is also modulated by cellular redox status. Mild or transient oxidative stress up-regulates the ubiquitination system and proteasome activity in cells and tissues and transiently enhances intracellular proteolysis. Severe or sustained oxidative stress impairs the function of the UPP and decreases intracellular proteolysis. Both the ubiquitin-conjugating enzymes and the proteasome can be inactivated by sustained oxidative stress, especially the 26S proteasome. Differential susceptibilities of the ubiquitin-conjugating enzymes and the 26S proteasome to oxidative damage lead to an accumulation of ubiquitin conjugates in cells in response to mild oxidative stress. Thus, increased levels of ubiquitin conjugates in cells seem to be an indicator of mild oxidative stress.
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Affiliation(s)
- Fu Shang
- Laboratory for Nutrition and Vision Research, USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111, USA.
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30
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Andersen KM, Jensen C, Kriegenburg F, Lauridsen AMB, Gordon C, Hartmann-Petersen R. Txl1 and Txc1 are co-factors of the 26S proteasome in fission yeast. Antioxid Redox Signal 2011; 14:1601-8. [PMID: 21091378 DOI: 10.1089/ars.2010.3329] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The 26S proteasome is a large proteolytic particle present in the cytosol and nucleus of eukaryotic cells. Most intracellular proteins, including those affected by oxidative damage, are degraded by the proteasome. The human thioredoxin, Txnl1, is known to associate with the 26S proteasome and thereby equips proteasomes with redox capabilities. Here, we characterize the fission yeast orthologue of Txnl1, called Txl1. Txl1 associates with the 26S proteasome via its C-terminal domain. This domain is also found in the uncharacterized protein, Txc1, which was also found to interact with 26S proteasomes. A txl1 null mutant, but not a txc1 null, displayed a synthetic growth defect with cut8, encoding a protein that tethers the proteasome to the nuclear membrane. Txc1 is present throughout the cytoplasm and nucleus, whereas Txl1 co-localizes with 26S proteasomes in both wild-type cells and in cut8 mutants, indicating that Txl1 is tightly associated with 26S proteasomes, while Txc1 might be only transiently bound to the complex. Finally, we show that Txl1 is an active thioredoxin. Accordingly, Txl1 was able to reduce and mediate the degradation of an oxidized model proteasome substrate in vitro. Thus, Txl1 and Txc1 are proteasome co-factors connected with oxidative stress.
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31
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Ettari R, Bonaccorso C, Micale N, Heindl C, Schirmeister T, Calabrò ML, Grasso S, Zappalà M. Development of Novel Peptidomimetics Containing a Vinyl Sulfone Moiety as Proteasome Inhibitors. ChemMedChem 2011; 6:1228-37. [DOI: 10.1002/cmdc.201100093] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Indexed: 01/30/2023]
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32
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Abstract
Human thymidylate synthase (hTS; EC 2.1.1.45) is one of a small group of proteasomal substrates whose intracellular degradation occurs in a ubiquitin-independent manner. Previous studies have shown that proteolytic breakdown of the hTS polypeptide is directed by an intrinsically disordered 27-residue domain at the N-terminal end of the molecule. This domain, in co-operation with an α-helix spanning amino acids 31–45, functions as a degron, in that it has the ability to destabilize a heterologous polypeptide to which it is attached. In the present study, we provide evidence indicating that it is the 26S isoform of the proteasome that is responsible for intracellular degradation of the hTS polypeptide. In addition, we have used targeted in vitro mutagenesis to show that an Arg–Arg motif at residues 10–11 is required for proteolysis, an observation that was confirmed by functional analysis of the TS N-terminus from other mammalian species. The effects of stabilizing mutations on hTS degradation are maintained when the enzyme is provided with an alternative means of proteasome association; thus such mutations perturb one or more post-docking steps in the degradation pathway. Surprisingly, deletion mutants missing large segments of the disordered domain still function as proteasomal substrates; however, degradation of such mutants occurs by a mechanism that is distinct from that for the wild-type protein. Taken together, our results provide information on the roles of specific subregions within the intrinsically disordered N-terminal domain of hTS in regulation of degradation, leading to a deeper understanding of mechanisms underlying the ubiquitin-independent proteasomal degradation pathway.
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33
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Sorokin AV, Kim ER, Ovchinnikov LP. Proteasome system of protein degradation and processing. BIOCHEMISTRY (MOSCOW) 2010; 74:1411-42. [PMID: 20210701 DOI: 10.1134/s000629790913001x] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In eukaryotic cells, degradation of most intracellular proteins is realized by proteasomes. The substrates for proteolysis are selected by the fact that the gate to the proteolytic chamber of the proteasome is usually closed, and only proteins carrying a special "label" can get into it. A polyubiquitin chain plays the role of the "label": degradation affects proteins conjugated with a ubiquitin (Ub) chain that consists at minimum of four molecules. Upon entering the proteasome channel, the polypeptide chain of the protein unfolds and stretches along it, being hydrolyzed to short peptides. Ubiquitin per se does not get into the proteasome, but, after destruction of the "labeled" molecule, it is released and labels another molecule. This process has been named "Ub-dependent protein degradation". In this review we systematize current data on the Ub-proteasome system, describe in detail proteasome structure, the ubiquitination system, and the classical ATP/Ub-dependent mechanism of protein degradation, as well as try to focus readers' attention on the existence of alternative mechanisms of proteasomal degradation and processing of proteins. Data on damages of the proteasome system that lead to the development of different diseases are given separately.
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Affiliation(s)
- A V Sorokin
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia.
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34
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Abstract
The ubiquitin-mediated degradation of proteins in numerous cellular processes, such as turnover and quality control of proteins, cell cycle and apoptosis, transcription and cell signaling, immune response and antigen presentation, and inflammation and development makes the ubiquitin-proteosome systems a very interesting target for various therapeutic interventions. Proteosome inhibitors were first synthesized as tools to probe the function and specificity of this particle's proteolytic activities. Most synthetic inhibitors rely on a peptide base, which mimics a protein substrate, attached at a COOH terminal "warhead". Notable warheads include boronic acids, such as Bortezomib and epoxyketones, such as carfilzomib. A variety of natural products also inhibit the proteosome that are not peptide-based, most notably lactacystin, that is related to NPI-0052, or salinosporamide A, another inhibitor in clinical trials. The possibility that proteosome inhibitors could be drug candidates was considered after studies showed that they induced apoptosis in leukemic cell lines. The first proteasome inhibitor in clinical application, Bortezomib showed activity in non small cell lung and androgen-independent prostate carcinoma, as well as MM and mantle cell and follicular non-Hodgkin's lymphoma. It is now lincensed for the treatment of newly diagnosed as well as relapsed/progressive MM and has had a major impact on the improvement in the treatment of MM in the last few years.
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Affiliation(s)
- Hermann Einsele
- Department of Internal Medicine II, University Hospital Würzburg, Josef-Schneider Strasse 2, Würzburg, 97080, Germany.
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35
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Zhao M, Zhang NY, Zurawel A, Hansen KC, Liu CW. Degradation of some polyubiquitinated proteins requires an intrinsic proteasomal binding element in the substrates. J Biol Chem 2009; 285:4771-80. [PMID: 20007692 DOI: 10.1074/jbc.m109.060095] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lysine 48-linked polyubiquitin chains usually target proteins for 26 S proteasomal degradation; however, this modification is not a warrant for destruction. Here, we found that efficient degradation of a physiological substrate UbcH10 requires not only an exogenous polyubiquitin chain modification but also its unstructured N-terminal region. Interestingly, the unstructured N-terminal region of UbcH10 directly binds the 19 S regulatory complex of the 26 S proteasome, and it mediates the initiation of substrate translocation. To promote ubiquitin-dependent degradation of the folded domains of UbcH10, its N-terminal region can be displaced by exogenous proteasomal binding elements. Moreover, the unstructured N-terminal region can initiate substrate translocation even when UbcH10 is artificially cyclized without a free terminus. Polyubiquitinated circular UbcH10 is completely degraded by the 26 S proteasome. Accordingly, we propose that degradation of some polyubiquitinated proteins requires two binding interactions: a polyubiquitin chain and an intrinsic proteasomal binding element in the substrates (likely an unstructured region); moreover, the intrinsic proteasomal binding element initiates substrate translocation regardless of its location in the substrates.
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Affiliation(s)
- Minglian Zhao
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
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36
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Kim YC, Wu SY, Lim HS, Chiang CM, Kodadek T. Non-proteolytic regulation of p53-mediated transcription through destabilization of the activator.promoter complex by the proteasomal ATPases. J Biol Chem 2009; 284:34522-30. [PMID: 19846554 DOI: 10.1074/jbc.m109.017277] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
It has been shown previously that sub-complexes of the 26 S proteasome can regulate gene expression via non-proteolytic mechanisms. One such mechanism is the disruption of activator.promoter complexes in an ATP-dependent fashion, which was discovered in the context of the yeast Gal4 system. This activity strongly inhibits Gal4-driven gene expression unless the activator is mono-ubiquitylated, which protects it from the ATPases. To address whether this paradigm is also applicable to medically important mammalian transcriptional activators we report here a study of the interaction of the proteasomal ATPases with p53. It is shown that p53 binds directly to the ATPases via its C-terminal tetramerization and regulatory domain and that p53.promoter complexes are indeed vulnerable to ATPase-dependent disruption by the ATPase complex in vitro. Knockdown of one of the ATPases, Rpt6, in living cells results in increased occupancy of the p21(waf1) promoter by p53 and increased expression of the gene, consistent with the idea that the proteasomal ATPases negatively regulate p53 function in a non-proteolytic fashion.
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Affiliation(s)
- Young-Chan Kim
- Division of Translational Research, Department of Internal Medicine, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390-9185, USA
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37
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The 19S ATPase S6a (S6'/TBP1) regulates the transcription initiation of class II transactivator. J Mol Biol 2009; 395:254-69. [PMID: 19853614 DOI: 10.1016/j.jmb.2009.10.035] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Revised: 10/13/2009] [Accepted: 10/14/2009] [Indexed: 01/24/2023]
Abstract
Class II transactivator (CIITA) is the master regulator of the major histocompatibility class II transcription complex (MHC-II) and is critical for initiation of adaptive immune responses. We have previously demonstrated that the 19S proteasome ATPase Sug1 plays a significant role in regulating CIITA activity and MHC-II expression. We now show that an additional component of the 19S complex, the 19S ATPase S6a (S6'/Tat-binding protein 1), is crucial for regulating cytokine-inducible transcription of CIITA. Lack of S6a negatively impacts CIITA activity and CIITA expression. Decreased expression of S6a significantly diminishes the recruitment of transcription factors to the CIITA interferon-gamma-inducible promoter [CIITA promoter IV (pIV)] and significantly decreases CIITApIV histone H3 and histone H4 acetylation, with a preferential loss of acetylation at H3 lysine 18 and H4 lysine 8. In addition, we provide evidence for the involvement of the 19S AAA (ATPases associated with diverse cellular activity) ATPase hexamer as the 19S ATPase S6b binds CIITApIV in an S6a-dependent fashion and has effects similar to S6a on CIITApIV histone acetylation. These analyses demonstrate the importance of 19S ATPases in the assembly of CIITApIV transcription machinery and provide additional insight into the regulatory mechanisms of the 19S proteasome in mammalian transcription.
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Koues OI, Dudley RK, Mehta NT, Greer SF. The 19S proteasome positively regulates histone methylation at cytokine inducible genes. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2009; 1789:691-701. [PMID: 19660582 DOI: 10.1016/j.bbagrm.2009.07.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2009] [Revised: 06/24/2009] [Accepted: 07/27/2009] [Indexed: 11/19/2022]
Abstract
Studies indicate that the 19S proteasome functions in the epigenetic regulation of transcription. We have shown that as in yeast, components of the 19S proteasome are crucial for regulating inducible histone acetylation events in mammalian cells. The 19S ATPase Sug1 binds to histone acetyltransferases and to acetylated histone H3 and, in the absence of Sug1, histone H3 acetylation is dramatically decreased at mammalian promoters. Research in yeast further indicates that the ortholog of Sug1, Rpt6, is a link between ubiquitination of histone H2B and H3 lysine 4 trimethylation (H3K4me3). To characterize the role that the 19S proteasome plays in regulating additional activating modifications, we examined the methylation and ubiquitination status of histones at inducible mammalian genes. We find that Sug1 is crucial for regulating histone H3K4me3 and H3R17me2 at the cytokine inducible MHC-II and CIITA promoters. In the absence of Sug1, histone H3K4me3 and H3R17me2 are dramatically decreased, but the loss of Sug1 has no significant effect on H3K36me3 or H2BK120ub. Our observation that a subunit of hCompass interacts with additional activating histone modifying enzymes, but fails to bind the CIITA promoter in the absence of Sug1, strongly implicates Sug1 in recruiting enzyme complexes responsible for initiating mammalian transcription.
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Affiliation(s)
- Olivia I Koues
- Division of Molecular Genetics and Biochemistry, Department of Biology, Georgia State University, Atlanta, Georgia 30302, USA
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Dunlop RA, Brunk UT, Rodgers KJ. Oxidized proteins: mechanisms of removal and consequences of accumulation. IUBMB Life 2009; 61:522-7. [PMID: 19391165 DOI: 10.1002/iub.189] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Elevated levels of oxidized proteins are reported in diseased tissue from age-related pathologies such as atherosclerosis, neurodegenerative disorders, and cataract. Unlike the precise mechanisms that exist for the repair of nucleic acids, lipids, and carbohydrates, the primary pathway for the repair of oxidized proteins is complete catabolism to their constitutive amino acids. This process can be inefficient as is evidenced by their accumulation. It is generally considered that damaged proteins are degraded by the proteasome; however, this is only true for mildly oxidized proteins, because substrates must be unfolded to enter the narrow catalytic core. Rather, evidence suggests that moderately or heavily oxidized proteins are endocytosed and enter the endosomal/lysosomal system, indicating co-operation between the proteasomes and the lysosomes. Heavily modified substrates are incompletely degraded and accumulate within the lysosomal compartments resulting in the formation of lipofuscin-like, autofluorescent aggregates. Accumulation eventually results in impaired turnover of large organelles such as proteasomes and mitochondria, lysosomal destablization, leakage of proteases into the cytosol and apoptosis. In this review, we summarize reports published since our last assessments of the field of oxidized protein degradation including a role for modified proteins in the induction of apoptosis.
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Affiliation(s)
- Rachael A Dunlop
- Cell Biology Group, Heart Research Institute, Camperdown, NSW, Australia.
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Thompson D, Hakala K, DeMartino GN. Subcomplexes of PA700, the 19 S regulator of the 26 S proteasome, reveal relative roles of AAA subunits in 26 S proteasome assembly and activation and ATPase activity. J Biol Chem 2009; 284:24891-903. [PMID: 19589775 DOI: 10.1074/jbc.m109.023218] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have identified, purified, and characterized three subcomplexes of PA700, the 19 S regulatory complex of the 26 S proteasome. These subcomplexes (denoted PS-1, PS-2, and PS-3) collectively account for all subunits present in purified PA700 but contain no overlapping components or significant levels of non-PA700 proteins. Each subcomplex contained two of the six AAA subunits (Rpt1-6) that form the binding interface of PA700 with the 20 S proteasome, the protease component of the 26 S proteasome. Unlike intact PA700, no individual PA700 subcomplex displayed ATPase activity or proteasome activating activity. However, both activities were manifested by ATP-dependent in vitro reconstitution of PA700 from the subcomplexes. We exploited functional reconstitution to define and distinguish roles of different PA700 subunits in PA700 function by selective alteration of subunits within individual subcomplexes prior to reconstitution. Carboxypeptidase treatment of either PS-2 or PS-3, subcomplexes containing specific Rpt subunits previously shown to have important roles in 26 S proteasome assembly and activation, inhibited these processes but did not affect PA700 reconstitution or ATPase activity. Thus, the intact C termini of both subunits are required for 26 S proteasome assembly and activation but not for PA700 reconstitution. Surprisingly, carboxypeptidase treatment of PS-1 also inhibited 26 S proteasome assembly and activation upon reconstitution with untreated PS-2 and PS-3. These results suggest a previously unidentified role for other PA700 subunits in 26 S proteasome assembly and activation. Our results reveal relative structural and functional relationships among the AAA subunits of PA700 and new insights about mechanisms of 26 S proteasome assembly and activation.
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Affiliation(s)
- David Thompson
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9040, USA
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Structure and Activity of the N-Terminal Substrate Recognition Domains in Proteasomal ATPases. Mol Cell 2009; 34:580-90. [DOI: 10.1016/j.molcel.2009.04.030] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2008] [Revised: 04/06/2009] [Accepted: 04/23/2009] [Indexed: 11/17/2022]
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Andersen KM, Madsen L, Prag S, Johnsen AH, Semple CA, Hendil KB, Hartmann-Petersen R. Thioredoxin Txnl1/TRP32 is a redox-active cofactor of the 26 S proteasome. J Biol Chem 2009; 284:15246-54. [PMID: 19349277 PMCID: PMC2685705 DOI: 10.1074/jbc.m900016200] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2009] [Revised: 03/30/2009] [Indexed: 01/18/2023] Open
Abstract
The 26 S proteasome is a large proteolytic machine, which degrades most intracellular proteins. We found that thioredoxin, Txnl1/TRP32, binds to Rpn11, a subunit of the regulatory complex of the human 26 S proteasome. Txnl1 is abundant, metabolically stable, and widely expressed and is present in the cytoplasm and nucleus. Txnl1 has thioredoxin activity with a redox potential of about -250 mV. Mutant Txnl1 with one active site cysteine replaced by serine formed disulfide bonds to eEF1A1, a substrate-recruiting factor of the 26 S proteasome. eEF1A1 is therefore a likely physiological substrate. In response to knockdown of Txnl1, ubiquitin-protein conjugates were moderately stabilized. Hence, Txnl1 is the first example of a direct connection between protein reduction and proteolysis, two major intracellular protein quality control mechanisms.
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Affiliation(s)
- Katrine M Andersen
- Department of Biology, University of Copenhagen, Universitetsparken 13, DK-2100 Copenhagen, Denmark
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Medalia N, Beer A, Zwickl P, Mihalache O, Beck M, Medalia O, Navon A. Architecture and molecular mechanism of PAN, the archaeal proteasome regulatory ATPase. J Biol Chem 2009; 284:22952-60. [PMID: 19363223 DOI: 10.1074/jbc.m809643200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In Archaea, an hexameric ATPase complex termed PAN promotes proteins unfolding and translocation into the 20 S proteasome. PAN is highly homologous to the six ATPases of the eukaryotic 19 S proteasome regulatory complex. Thus, insight into the mechanism of PAN function may reveal a general mode of action mutual to the eukaryotic 19 S proteasome regulatory complex. In this study we generated a three-dimensional model of PAN from tomographic reconstruction of negatively stained particles. Surprisingly, this reconstruction indicated that the hexameric complex assumes a two-ring structure enclosing a large cavity. Assessment of distinct three-dimensional functional states of PAN in the presence of adenosine 5'-O-(thiotriphosphate) and ADP and in the absence of nucleotides outlined a possible mechanism linking nucleotide binding and hydrolysis to substrate recognition, unfolding, and translocation. A novel feature of the ATPase complex revealed in this study is a gate controlling the "exit port" of the regulatory complex and, presumably, translocation into the 20 S proteasome. Based on our structural and biochemical findings, we propose a possible model in which substrate binding and unfolding are linked to structural transitions driven by nucleotide binding and hydrolysis, whereas translocation into the proteasome only depends upon the presence of an unfolded substrate and binding but not hydrolysis of nucleotide.
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Affiliation(s)
- Noa Medalia
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot 76100, Israel
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Jung T, Höhn A, Catalgol B, Grune T. Age-related differences in oxidative protein-damage in young and senescent fibroblasts. Arch Biochem Biophys 2008; 483:127-35. [PMID: 19135972 DOI: 10.1016/j.abb.2008.12.007] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Revised: 12/05/2008] [Accepted: 12/12/2008] [Indexed: 01/10/2023]
Abstract
Aging is accompanied by an accumulation of oxidized proteins and cross-linked modified protein material. The intracellular formation and accumulation of highly oxidized and cross-linked proteins, the so-called lipofuscin, is a typical sign of senescence. However, little is known whether the lipofuscin accumulation during aging is related to environmental conditions, as oxidative stress, and whether the accumulation of oxidized proteins and lipofuscin is preferentially taking place in the cytosol or the nucleus and finally, what is the role of lysosomes in this process. Therefore, we investigated human skin fibroblasts in an early stage of proliferation ("young cells") and in a late stage ("senescent cells"). Such cells were compared for the amount of protein carbonyls and lipofuscin and their distribution within the cytosol and the nucleus. Furthermore, cells were exposed to single and repeated doses of hydrogen peroxide and paraquat, measuring the same set of parameters. In addition to that the role of the proteasome to degrade oxidized proteins in young and senescent cells was tested. Furthermore, detailed microscopic analysis was performed testing the intracellular distribution of lipofuscin. The results clearly demonstrated that repeated/chronic oxidative stress induces a senescence-like phenotype of the distribution of oxidized proteins as well as of lipofuscin. It could be demonstrated that most of the lipofuscin is located in lysosomes and that senescent cells contain less lysosomes not lipofuscin-laden in comparison to young cells.
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Affiliation(s)
- Tobias Jung
- Institute for Biological Chemistry and Nutrition, Biofunctionality and Food Safety, University of Hohenheim, Stuttgart, Germany
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Mearini G, Schlossarek S, Willis MS, Carrier L. The ubiquitin–proteasome system in cardiac dysfunction. Biochim Biophys Acta Mol Basis Dis 2008; 1782:749-63. [DOI: 10.1016/j.bbadis.2008.06.009] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Revised: 06/12/2008] [Accepted: 06/18/2008] [Indexed: 12/31/2022]
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Regulation of acetylation at the major histocompatibility complex class II proximal promoter by the 19S proteasomal ATPase Sug1. Mol Cell Biol 2008; 28:5837-50. [PMID: 18662994 DOI: 10.1128/mcb.00535-08] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Recent studies have made evident the fact that the 19S regulatory component of the proteasome has functions that extend beyond degradation, particularly in the regulation of transcription. Although 19S ATPases facilitate chromatin remodeling and acetylation events in yeast (Saccharomyces cerevisiae), it is unclear if they play similar roles in mammalian cells. We have recently shown that the 19S ATPase Sug1 positively regulates the transcription of the critical inflammatory gene for major histocompatibility complex class II (MHC-II) by stabilizing enhanceosome assembly at the proximal promoter. We now show that Sug1 is crucial for regulating histone H3 acetylation at the MHC-II proximal promoter. Sug1 binds to acetylated histone H3 and, in the absence of Sug1, histone H3 acetylation is dramatically decreased at the proximal promoter, with a preferential loss of acetylation at H3 lysine 18. Sug1 also binds to the MHC-II histone acetyltransferase CREB-binding protein (CBP) and is critical for the recruitment of CBP to the MHC-II proximal promoter. Our current study strongly implicates the 19S ATPase Sug1 in modifying histones to initiate MHC-II transcription and provides novel insights into the role of the proteasome in the regulation of mammalian transcription.
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MANDEL SILVIA, GRUNBLATT EDNA, RIEDERER PETER, AMARIGLIO NINETTE, HIRSCH JASMINEJACOB, RECHAVI GIDEON, YOUDIM MOUSSABH. Gene Expression Profiling of Sporadic Parkinson's Disease Substantia Nigra Pars Compacta Reveals Impairment of Ubiquitin-Proteasome Subunits, SKP1A, Aldehyde Dehydrogenase, and Chaperone HSC-70. Ann N Y Acad Sci 2008. [DOI: 10.1111/j.1749-6632.2005.tb00044.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Jariel-Encontre I, Bossis G, Piechaczyk M. Ubiquitin-independent degradation of proteins by the proteasome. Biochim Biophys Acta Rev Cancer 2008; 1786:153-77. [PMID: 18558098 DOI: 10.1016/j.bbcan.2008.05.004] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Revised: 05/15/2008] [Accepted: 05/15/2008] [Indexed: 02/08/2023]
Abstract
The proteasome is the main proteolytic machinery of the cell and constitutes a recognized drugable target, in particular for treating cancer. It is involved in the elimination of misfolded, altered or aged proteins as well as in the generation of antigenic peptides presented by MHC class I molecules. It is also responsible for the proteolytic maturation of diverse polypeptide precursors and for the spatial and temporal regulation of the degradation of many key cell regulators whose destruction is necessary for progression through essential processes, such as cell division, differentiation and, more generally, adaptation to environmental signals. It is generally believed that proteins must undergo prior modification by polyubiquitin chains to be addressed to, and recognized by, the proteasome. In reality, however, there is accumulating evidence that ubiquitin-independent proteasomal degradation may have been largely underestimated. In particular, a number of proto-oncoproteins and oncosuppressive proteins are privileged ubiquitin-independent proteasomal substrates, the altered degradation of which may have tumorigenic consequences. The identification of ubiquitin-independent mechanisms for proteasomal degradation also poses the paramount question of the multiplicity of catabolic pathways targeting each protein substrate. As this may help design novel therapeutic strategies, the underlying mechanisms are critically reviewed here.
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Affiliation(s)
- Isabelle Jariel-Encontre
- Institut de Génétique Moléculaire de Montpellier, CNRS, UMR5535, IFR122, 1919 Route de Mende, Montpellier, F-34293, France
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The central unit within the 19S regulatory particle of the proteasome. Nat Struct Mol Biol 2008; 15:573-80. [PMID: 18511945 PMCID: PMC2481239 DOI: 10.1038/nsmb.1427] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2008] [Accepted: 04/10/2008] [Indexed: 11/27/2022]
Abstract
The 26S proteasome is a multisubunit enzyme composed of a cylindrical catalytic core (20S) and a regulatory particle (19S) that together perform the essential degradation of cellular proteins tagged by ubiquitin. To date, however, substrate trajectory within the complex remains elusive. Here we describe a previously unknown functional unit within the 19S, comprising two subunits, Rpn1 and Rpn2. These toroids physically link the site of substrate recruitment with the site of proteolysis. Rpn2 interfaces with the 20S, whereas Rpn1 sits atop Rpn2, serving as a docking site for a substrate-recruitment factor. The 19S ATPases encircle the Rpn1-Rpn2 stack, covering the remainder of the 20S surface. Both Rpn1-Rpn2 and the ATPases are required for substrate translocation and gating of the proteolytic channel. Similar pairing of units is found in unfoldases and nuclear transporters, exposing common features of these protein nanomachines.
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50
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Inobe T, Matouschek A. Protein targeting to ATP-dependent proteases. Curr Opin Struct Biol 2008; 18:43-51. [PMID: 18276129 DOI: 10.1016/j.sbi.2007.12.014] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2007] [Revised: 12/21/2007] [Accepted: 12/26/2007] [Indexed: 11/27/2022]
Abstract
ATP-dependent proteases control diverse cellular processes by degrading specific regulatory proteins. Recent work has shown that protein substrates are specifically transferred to ATP-dependent proteases through different routes. These routes can function in parallel or independently. In all of these targeting mechanisms, it can be useful to separate two steps: substrate binding to the protease and initiation of degradation.
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Affiliation(s)
- Tomonao Inobe
- Department of Biochemistry, Molecular Biology and Cell Biology, 2205 Tech Drive, Hogan 2-100 Northwestern University, Evanston, IL, USA
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