1
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Varshavsky A. N-degron pathways. Proc Natl Acad Sci U S A 2024; 121:e2408697121. [PMID: 39264755 DOI: 10.1073/pnas.2408697121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/14/2024] Open
Abstract
An N-degron is a degradation signal whose main determinant is a "destabilizing" N-terminal residue of a protein. Specific N-degrons, discovered in 1986, were the first identified degradation signals in short-lived intracellular proteins. These N-degrons are recognized by a ubiquitin-dependent proteolytic system called the Arg/N-degron pathway. Although bacteria lack the ubiquitin system, they also have N-degron pathways. Studies after 1986 have shown that all 20 amino acids of the genetic code can act, in specific sequence contexts, as destabilizing N-terminal residues. Eukaryotic proteins are targeted for the conditional or constitutive degradation by at least five N-degron systems that differ both functionally and mechanistically: the Arg/N-degron pathway, the Ac/N-degron pathway, the Pro/N-degron pathway, the fMet/N-degron pathway, and the newly named, in this perspective, GASTC/N-degron pathway (GASTC = Gly, Ala, Ser, Thr, Cys). I discuss these systems and the expanded terminology that now encompasses the entire gamut of known N-degron pathways.
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Affiliation(s)
- Alexander Varshavsky
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
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2
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Zhao X, Xu C, Ding Y, Yan N. The multifaceted functions of NFE2L1 in metabolism and associated disorders. Life Sci 2024; 352:122906. [PMID: 38992575 DOI: 10.1016/j.lfs.2024.122906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 07/05/2024] [Accepted: 07/08/2024] [Indexed: 07/13/2024]
Abstract
Nuclear factor erythroid 2-related factor 1 (NFE2L1, also known as Nrf1) is a crucial member of the CNC-bZIP subfamily of transcription factors expressed ubiquitously throughout our body. Recent findings have revealed its association with various metabolic processes, encompassing glucose, lipid, and protein metabolism. In the realm of glucose metabolism, NFE2L1 exerts regulatory control by modulating pancreatic β cells and insulin production. It also influences glucose metabolism in liver and the insulin sensitivity of adipose tissue. Regarding lipid metabolism, NFE2L1 governs this process by influencing the expression of specific adipogenic and lipolysis genes in both liver and adipose tissue. Additionally, NFE2L1 regulates specific lipids, such as cholesterol. These involvements underlie various manifestations of NFE2L1 deficiency such as adipocyte hypertrophy, inflammation, and steatohepatitis. In the realm of protein metabolism, NFE2L1 serves as a major transcription factor regulating the 26S proteasome genes expression, which dysfunction has been related with multiple diseases including neurodegenerative diseases, cancers, autoimmune conditions, etc. In this comprehensive review, we summarize the diverse roles that NFE2L1 plays in glucose, lipid, and protein metabolism, as well as its impact on diseases related to these metabolic processes.
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Affiliation(s)
- Xuye Zhao
- Department of Biochemistry and Molecular Biology, School of Basic Medical Science, Jiangxi Medical College, Nanchang University, Nanchang, Jiangxi 330006, China; Queen Mary College, Jiangxi Medical College, Nanchang University, Nanchang, Jiangxi 330031, China; School of Biological and Biomedical Sciences, Queen Mary University of London, London, United Kingdom
| | - Chang Xu
- Department of Biochemistry and Molecular Biology, School of Basic Medical Science, Jiangxi Medical College, Nanchang University, Nanchang, Jiangxi 330006, China; Queen Mary College, Jiangxi Medical College, Nanchang University, Nanchang, Jiangxi 330031, China; School of Biological and Biomedical Sciences, Queen Mary University of London, London, United Kingdom
| | - Yi Ding
- Department of Spine Surgery, Ganzhou People's Hospital (The Affiliated Ganzhou Hospital of Nanchang University), Ganzhou, Jiangxi Province 341000, China
| | - Nianlong Yan
- Department of Biochemistry and Molecular Biology, School of Basic Medical Science, Jiangxi Medical College, Nanchang University, Nanchang, Jiangxi 330006, China.
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3
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Galka D, Ali TT, Bast A, Niederleithinger M, Gerhardt E, Motosugi R, Sakata E, Knop M, Outeiro TF, Popova B, Braus GH. Inhibition of 26S proteasome activity by α-synuclein is mediated by the proteasomal chaperone Rpn14/PAAF1. Aging Cell 2024; 23:e14128. [PMID: 38415292 PMCID: PMC11113265 DOI: 10.1111/acel.14128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 02/01/2024] [Accepted: 02/11/2024] [Indexed: 02/29/2024] Open
Abstract
Parkinson's disease (PD) is characterized by aggregation of α-synuclein (α-syn) into protein inclusions in degenerating brains. Increasing amounts of aggregated α-syn species indicate significant perturbation of cellular proteostasis. Altered proteostasis depends on α-syn protein levels and the impact of α-syn on other components of the proteostasis network. Budding yeast Saccharomyces cerevisiae was used as eukaryotic reference organism to study the consequences of α-syn expression on protein dynamics. To address this, we investigated the impact of overexpression of α-syn and S129A variant on the abundance and stability of most yeast proteins using a genome-wide yeast library and a tandem fluorescent protein timer (tFT) reporter as a measure for protein stability. This revealed that the stability of in total 377 cellular proteins was altered by α-syn expression, and that the impact on protein stability was significantly enhanced by phosphorylation at Ser129 (pS129). The proteasome assembly chaperone Rpn14 was identified as one of the top candidates for increased protein stability by expression of pS129 α-syn. Elevated levels of Rpn14 enhanced the growth inhibition by α-syn and the accumulation of ubiquitin conjugates in the cell. We found that Rpn14 interacts physically with α-syn and stabilizes pS129 α-syn. The expression of α-syn along with elevated levels of Rpn14 or its human counterpart PAAF1 reduced the proteasome activity in yeast and in human cells, supporting that pS129 α-syn negatively affects the 26S proteasome through Rpn14. This comprehensive study into the alternations of protein homeostasis highlights the critical role of the Rpn14/PAAF1 in α-syn-mediated proteasome dysfunction.
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Affiliation(s)
- Dajana Galka
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and GeneticsUniversity of GöttingenGöttingenGermany
| | - Tariq T. Ali
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and GeneticsUniversity of GöttingenGöttingenGermany
| | - Alexander Bast
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and GeneticsUniversity of GöttingenGöttingenGermany
| | - Marie Niederleithinger
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and GeneticsUniversity of GöttingenGöttingenGermany
| | - Ellen Gerhardt
- Department of Experimental Neurodegeneration, Center for Biostructural Imaging of NeurodegenerationUniversity Medical Center GöttingenGöttingenGermany
| | - Ryo Motosugi
- Institute for Auditory NeuroscienceUniversity Medical Center GöttingenGöttingenGermany
- Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells (MBExC)University of GöttingenGöttingenGermany
| | - Eri Sakata
- Institute for Auditory NeuroscienceUniversity Medical Center GöttingenGöttingenGermany
- Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells (MBExC)University of GöttingenGöttingenGermany
| | - Michael Knop
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ‐ZMBH AllianceHeidelberg UniversityHeidelbergGermany
| | - Tiago F. Outeiro
- Department of Experimental Neurodegeneration, Center for Biostructural Imaging of NeurodegenerationUniversity Medical Center GöttingenGöttingenGermany
- Translational and Clinical Research Institute, Faculty of Medical SciencesNewcastle UniversityNewcastle Upon TyneUK
- Max Planck Institute for Multidisciplinary SciencesGöttingenGermany
- Scientific employee with an honorary contract at Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE)GöttingenGermany
| | - Blagovesta Popova
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and GeneticsUniversity of GöttingenGöttingenGermany
| | - Gerhard H. Braus
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and GeneticsUniversity of GöttingenGöttingenGermany
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4
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Cascio P. PA28γ, the ring that makes tumors invisible to the immune system? Biochimie 2024:S0300-9084(24)00078-6. [PMID: 38631454 DOI: 10.1016/j.biochi.2024.04.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 03/29/2024] [Accepted: 04/12/2024] [Indexed: 04/19/2024]
Abstract
PA28γ is a proteasomal interactor whose main and most known function is to stimulate the hydrolytic activity of the 20 S proteasome independently of ubiquitin and ATP. Unlike its two paralogues, PA28α and PA28β, PA28γ is largely present in the nuclear compartment and plays pivotal functions in important pathways such as cellular division, apoptosis, neoplastic transformation, chromatin structure and organization, fertility, lipid metabolism, and DNA repair mechanisms. Although it is known that a substantial fraction of PA28γ is found in the cell in a free form (i.e. not associated with 20 S), almost all of the studies so far have focused on its ability to modulate proteasomal enzymatic activities. In this respect, the ability of PA28γ to strongly stimulate degradation of proteins, especially if intrinsically disordered and therefore devoid of three-dimensional tightly folded structure, appears to be the main molecular mechanism underlying its multiple biological effects. Initial studies, conducted more than 20 years ago, came to the conclusion that among the many biological functions of PA28γ, the immunological ones were rather limited and circumscribed. In this review, we focus on recent evidence showing that PA28γ fulfills significant functions in cell-mediated acquired immunity, with a particular role in attenuating MHC class I antigen presentation, especially in relation to neoplastic transformation and autoimmune diseases.
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Affiliation(s)
- Paolo Cascio
- Department of Veterinary Sciences, University of Turin, Largo P. Braccini 2, 10095, Grugliasco, Turin, Italy.
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5
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Semchonok DA, Kyrilis FL, Hamdi F, Kastritis PL. Cryo-EM of a heterogeneous biochemical fraction elucidates multiple protein complexes from a multicellular thermophilic eukaryote. J Struct Biol X 2023; 8:100094. [PMID: 37638207 PMCID: PMC10451023 DOI: 10.1016/j.yjsbx.2023.100094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 07/27/2023] [Accepted: 08/07/2023] [Indexed: 08/29/2023] Open
Abstract
Biomolecular complexes and their interactions govern cellular structure and function. Understanding their architecture is a prerequisite for dissecting the cell's inner workings, but their higher-order assembly is often transient and challenging for structural analysis. Here, we performed cryo-EM on a single, highly heterogeneous biochemical fraction derived from Chaetomium thermophilum cell extracts to visualize the biomolecular content of the multicellular eukaryote. After cryo-EM single-particle image processing, results showed that a simultaneous three-dimensional structural characterization of multiple chemically diverse biomacromolecules is feasible. Namely, the thermophilic, eukaryotic complexes of (a) ATP citrate-lyase, (b) Hsp90, (c) 20S proteasome, (d) Hsp60 and (e) UDP-glucose pyrophosphorylase were characterized. In total, all five complexes have been structurally dissected in a thermophilic eukaryote in a total imaged sample area of 190.64 μm2, and two, in particular, 20S proteasome and Hsp60, exhibit side-chain resolution features. The C. thermophilum Hsp60 near-atomic model was resolved at 3.46 Å (FSC = 0.143) and shows a hinge-like conformational change of its equatorial domain, highly similar to the one previously shown for its bacterial orthologue, GroEL. This work demonstrates that cryo-EM of cell extracts will greatly accelerate the structural analysis of cellular complexes and provide unprecedented opportunities to annotate architectures of biomolecules in a holistic approach.
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Affiliation(s)
- Dmitry A. Semchonok
- Interdisciplinary Research Center HALOmem, Charles Tanford Protein Center, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Straße 3a, Halle/Saale, Germany
| | - Fotis L. Kyrilis
- Interdisciplinary Research Center HALOmem, Charles Tanford Protein Center, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Straße 3a, Halle/Saale, Germany
- Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Straße 3, Halle/Saale, Germany
- Institute of Chemical Biology, National Hellenic Research Foundation, Athens, Greece
| | - Farzad Hamdi
- Interdisciplinary Research Center HALOmem, Charles Tanford Protein Center, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Straße 3a, Halle/Saale, Germany
| | - Panagiotis L. Kastritis
- Interdisciplinary Research Center HALOmem, Charles Tanford Protein Center, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Straße 3a, Halle/Saale, Germany
- Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Straße 3, Halle/Saale, Germany
- Institute of Chemical Biology, National Hellenic Research Foundation, Athens, Greece
- Biozentrum, Martin Luther University Halle-Wittenberg, Weinbergweg 22, Halle/Saale, Germany
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6
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Pispa J, Mikkonen E, Arpalahti L, Jin C, Martínez-Fernández C, Cerón J, Holmberg CI. AKIR-1 regulates proteasome subcellular function in Caenorhabditis elegans. iScience 2023; 26:107886. [PMID: 37767001 PMCID: PMC10520889 DOI: 10.1016/j.isci.2023.107886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 07/07/2023] [Accepted: 09/07/2023] [Indexed: 09/29/2023] Open
Abstract
Polyubiquitinated proteins are primarily degraded by the ubiquitin-proteasome system (UPS). Proteasomes are present both in the cytoplasm and nucleus. Here, we investigated mechanisms coordinating proteasome subcellular localization and activity in a multicellular organism. We identified the nuclear protein-encoding gene akir-1 as a proteasome regulator in a genome-wide Caenorhabditis elegans RNAi screen. We demonstrate that depletion of akir-1 causes nuclear accumulation of endogenous polyubiquitinated proteins in intestinal cells, concomitant with slower in vivo proteasomal degradation in this subcellular compartment. Remarkably, akir-1 is essential for nuclear localization of proteasomes both in oocytes and intestinal cells but affects differentially the subcellular distribution of polyubiquitinated proteins. We further reveal that importin ima-3 genetically interacts with akir-1 and influences nuclear localization of a polyubiquitin-binding reporter. Our study shows that the conserved AKIR-1 is an important regulator of the subcellular function of proteasomes in a multicellular organism, suggesting a role for AKIR-1 in proteostasis maintenance.
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Affiliation(s)
- Johanna Pispa
- Department of Biochemistry and Developmental Biology, Medicum, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland
| | - Elisa Mikkonen
- Department of Biochemistry and Developmental Biology, Medicum, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland
| | - Leena Arpalahti
- Department of Biochemistry and Developmental Biology, Medicum, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland
| | - Congyu Jin
- Department of Anatomy, Medicum, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland
| | - Carmen Martínez-Fernández
- Modeling Human Diseases in C. elegans Group, Genes, Diseases, and Therapies Program, Institut d'Investigació Biomèdica de Bellvitge - IDIBELL, L'Hospitalet de Llobregat, 08908 Barcelona, Spain
| | - Julián Cerón
- Modeling Human Diseases in C. elegans Group, Genes, Diseases, and Therapies Program, Institut d'Investigació Biomèdica de Bellvitge - IDIBELL, L'Hospitalet de Llobregat, 08908 Barcelona, Spain
| | - Carina I. Holmberg
- Department of Biochemistry and Developmental Biology, Medicum, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland
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7
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Cerruti F, Borrelli A, Degiovanni A, Mengozzi G, Borella F, Cascio P. Detection and biochemical characterization of circulating proteasomes in dog plasma. Res Vet Sci 2023; 162:104950. [PMID: 37453228 DOI: 10.1016/j.rvsc.2023.104950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 06/22/2023] [Accepted: 07/01/2023] [Indexed: 07/18/2023]
Abstract
A growing body of evidence convincingly indicates that proteasomes are not located exclusively within cells but also in different extracellular compartments. In humans, in fact, this large multimeric protease has been identified in many body fluids and secretions such as blood, urine, tears, sweat, saliva, milk, and cerebrospinal and pericardial fluid. Intriguingly, the exact origins of these extracellular proteasomes as well as the specific biological functions they perform are largely unknown. As no data on this important subject is yet available in domestic animals, the present study was undertaken to investigate the presence of extracellular proteasomes in canine blood. As a result, for the first time, circulating proteasomes could be clearly detected in the plasma of a cohort of 20 healthy dogs. Furthermore, all three main proteasomal peptidase activities were measured and characterized using fluorogenic peptides and highly specific inhibitors. Finally, the effect of ATP and PA28 family activators on this circulating proteasome was investigated. Collectively, our data indicate that at least a part of the proteasome present in dog plasma consists of a particle that in vitro displays the enzymatic properties of the 20S proteasome.
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Affiliation(s)
- F Cerruti
- Department of Veterinary Sciences, University of Turin, Largo P. Braccini, 2, 10095, Grugliasco, Turin, Italy
| | - A Borrelli
- Department of Veterinary Sciences, University of Turin, Largo P. Braccini, 2, 10095, Grugliasco, Turin, Italy
| | - A Degiovanni
- Department of Veterinary Sciences, University of Turin, Largo P. Braccini, 2, 10095, Grugliasco, Turin, Italy
| | - G Mengozzi
- Department of Public Health and Pediatric Sciences, University of Turin, C.so Bramante, 88/90, 10100 Turin, Italy
| | - F Borella
- Department of Veterinary Sciences, University of Turin, Largo P. Braccini, 2, 10095, Grugliasco, Turin, Italy
| | - P Cascio
- Department of Veterinary Sciences, University of Turin, Largo P. Braccini, 2, 10095, Grugliasco, Turin, Italy.
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8
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Hsu HC, Wang J, Kjellgren A, Li H, DeMartino GN. Ηigh-resolution structure of mammalian PI31-20S proteasome complex reveals mechanism of proteasome inhibition. J Biol Chem 2023; 299:104862. [PMID: 37236357 PMCID: PMC10319324 DOI: 10.1016/j.jbc.2023.104862] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 05/08/2023] [Accepted: 05/18/2023] [Indexed: 05/28/2023] Open
Abstract
Proteasome-catalyzed protein degradation mediates and regulates critical aspects of many cellular functions and is an important element of proteostasis in health and disease. Proteasome function is determined in part by the types of proteasome holoenzymes formed between the 20S core particle that catalyzes peptide bond hydrolysis and any of multiple regulatory proteins to which it binds. One of these regulators, PI31, was previously identified as an in vitro 20S proteasome inhibitor, but neither the molecular mechanism nor the possible physiologic significance of PI31-mediated proteasome inhibition has been clear. Here we report a high-resolution cryo-EM structure of the mammalian 20S proteasome in complex with PI31. The structure shows that two copies of the intrinsically disordered carboxyl terminus of PI31 are present in the central cavity of the closed-gate conformation of the proteasome and interact with proteasome catalytic sites in a manner that blocks proteolysis of substrates but resists their own degradation. The two inhibitory polypeptide chains appear to originate from PI31 monomers that enter the catalytic chamber from opposite ends of the 20S cylinder. We present evidence that PI31 can inhibit proteasome activity in mammalian cells and may serve regulatory functions for the control of cellular proteostasis.
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Affiliation(s)
- Hao-Chi Hsu
- Department of Structural Biology, Van Andel Institute, Grand Rapids, Michigan, USA
| | - Jason Wang
- Department of Physiology, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Abbey Kjellgren
- Department of Physiology, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Huilin Li
- Department of Structural Biology, Van Andel Institute, Grand Rapids, Michigan, USA.
| | - George N DeMartino
- Department of Physiology, UT Southwestern Medical Center, Dallas, Texas, USA.
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9
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Li S, Jia X, Niu T, Zhang X, Qi C, Xu W, Deng H, Sun F, Ji G. HOPE-SIM, a cryo-structured illumination fluorescence microscopy system for accurately targeted cryo-electron tomography. Commun Biol 2023; 6:474. [PMID: 37120442 PMCID: PMC10148829 DOI: 10.1038/s42003-023-04850-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 04/18/2023] [Indexed: 05/01/2023] Open
Abstract
Cryo-focused ion beam (cryo-FIB) milling technology has been developed for the fabrication of cryo-lamella of frozen native specimens for study by in situ cryo-electron tomography (cryo-ET). However, the precision of the target of interest is still one of the major bottlenecks limiting application. Here, we have developed a cryo-correlative light and electron microscopy (cryo-CLEM) system named HOPE-SIM by incorporating a 3D structured illumination fluorescence microscopy (SIM) system and an upgraded high-vacuum stage to achieve efficiently targeted cryo-FIB. With the 3D super resolution of cryo-SIM as well as our cryo-CLEM software, 3D-View, the correlation precision of targeting region of interest can reach to 110 nm enough for the subsequent cryo-lamella fabrication. We have successfully utilized the HOPE-SIM system to prepare cryo-lamellae targeting mitochondria, centrosomes of HeLa cells and herpesvirus assembly compartment of infected BHK-21 cells, which suggests the high potency of the HOPE-SIM system for future in situ cryo-ET workflows.
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Affiliation(s)
- Shuoguo Li
- Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China
- National Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Xing Jia
- Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China
| | - Tongxin Niu
- Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China
| | - Xiaoyun Zhang
- Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China
| | - Chen Qi
- Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China
| | - Wei Xu
- Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China
| | - Hongyu Deng
- University of Chinese Academy of Sciences, 100049, Beijing, China
- CAS Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China
- CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China
| | - Fei Sun
- Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China.
- National Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China.
- University of Chinese Academy of Sciences, 100049, Beijing, China.
- CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China.
| | - Gang Ji
- Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China.
- University of Chinese Academy of Sciences, 100049, Beijing, China.
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10
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Hsu HC, Wang J, Kjellgren A, Li H, DeMartino GN. High-resolution structure of mammalian PI31â€"20S proteasome complex reveals mechanism of proteasome inhibition. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.03.535455. [PMID: 37066326 PMCID: PMC10103979 DOI: 10.1101/2023.04.03.535455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Proteasome-catalyzed protein degradation mediates and regulates critical aspects of many cellular functions and is an important element of proteostasis in health and disease. Proteasome function is determined in part by the types of proteasome holoenzymes formed between the 20S core particle that catalyzes peptide bond hydrolysis and any of multiple regulatory proteins to which it binds. One of these regulators, PI31, was previously identified as an in vitro 20S proteasome inhibitor, but neither the molecular mechanism nor the possible physiologic significance of PI31-mediated proteasome inhibition has been clear. Here we report a high- resolution cryo-EM structure of the mammalian 20S proteasome in complex with PI31. The structure shows that two copies of the intrinsically-disordered carboxyl-terminus of PI31 are present in the central cavity of the closed-gate conformation of the proteasome and interact with proteasome catalytic sites in a manner that blocks proteolysis of substrates but resists their own degradation. The two inhibitory polypeptide chains appear to originate from PI31 monomers that enter the catalytic chamber from opposite ends of the 20S cylinder. We present evidence that PI31 can inhibit proteasome activity in mammalian cells and may serve regulatory functions for the control of cellular proteostasis.
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11
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Abstract
Our understanding of the ubiquitin code has greatly evolved from conventional E1, E2 and E3 enzymes that modify Lys residues on specific substrates with a single type of ubiquitin chain to more complex processes that regulate and mediate ubiquitylation. In this Review, we discuss recently discovered endogenous mechanisms and unprecedented pathways by which pathogens rewrite the ubiquitin code to promote infection. These processes include unconventional ubiquitin modifications involving ester linkages with proteins, lipids and sugars, or ubiquitylation through a phosphoribosyl bridge involving Arg42 of ubiquitin. We also introduce the enzymatic pathways that write and reverse these modifications, such as the papain-like proteases of severe acute respiratory syndrome coronavirus (SARS-CoV) and SARS-CoV-2. Furthermore, structural studies have revealed that the ultimate functions of ubiquitin are mediated not simply by straightforward recognition by ubiquitin-binding domains. Instead, elaborate multivalent interactions between ubiquitylated targets or ubiquitin chains and their readers (for example, the proteasome, the MLL1 complex or DOT1L) can elicit conformational changes that regulate protein degradation or transcription. The newly discovered mechanisms provide opportunities for innovative therapeutic interventions for diseases such as cancer and infectious diseases.
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Affiliation(s)
- Ivan Dikic
- Institute of Biochemistry II, Faculty of Medicine, Goethe University, Frankfurt, Germany.
- Buchmann Institute for Molecular Life Sciences, Goethe University, Frankfurt, Germany.
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12
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Li S, Wang Z, Jia X, Niu T, Zhang J, Yin G, Zhang X, Zhu Y, Ji G, Sun F. ELI trifocal microscope: a precise system to prepare target cryo-lamellae for in situ cryo-ET study. Nat Methods 2023; 20:276-283. [PMID: 36646897 PMCID: PMC9911351 DOI: 10.1038/s41592-022-01748-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 12/06/2022] [Indexed: 01/18/2023]
Abstract
Cryo-electron tomography (cryo-ET) has become a powerful approach to study the high-resolution structure of cellular macromolecular machines in situ. However, the current correlative cryo-fluorescence and electron microscopy lacks sufficient accuracy and efficiency to precisely prepare cryo-lamellae of target locations for subsequent cryo-ET. Here we describe a precise cryogenic fabrication system, ELI-TriScope, which sets electron (E), light (L) and ion (I) beams at the same focal point to achieve accurate and efficient preparation of a target cryo-lamella. ELI-TriScope uses a commercial dual-beam scanning electron microscope modified to incorporate a cryo-holder-based transfer system and embed an optical imaging system just underneath the vitrified specimen. Cryo-focused ion beam milling can be accurately navigated by monitoring the real-time fluorescence signal of the target molecule. Using ELI-TriScope, we prepared a batch of cryo-lamellae of HeLa cells targeting the centrosome with a success rate of ~91% and discovered new in situ structural features of the human centrosome by cryo-ET.
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Affiliation(s)
- Shuoguo Li
- Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Ziyan Wang
- University of Chinese Academy of Sciences, Beijing, China
- National Key Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Xing Jia
- Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Tongxin Niu
- Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Jianguo Zhang
- Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Guoliang Yin
- University of Chinese Academy of Sciences, Beijing, China
- National Key Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Xiaoyun Zhang
- Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Yun Zhu
- University of Chinese Academy of Sciences, Beijing, China.
- National Key Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
| | - Gang Ji
- Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
- University of Chinese Academy of Sciences, Beijing, China.
| | - Fei Sun
- Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
- University of Chinese Academy of Sciences, Beijing, China.
- National Key Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
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13
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The β-Grasp Domain of Proteasomal ATPase Mpa Makes Critical Contacts with the Mycobacterium tuberculosis 20S Core Particle to Facilitate Degradation. mSphere 2022; 7:e0027422. [PMID: 35993699 PMCID: PMC9599533 DOI: 10.1128/msphere.00274-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Mycobacterium tuberculosis possesses a Pup-proteasome system analogous to the eukaryotic ubiquitin-proteasome pathway. We have previously shown that the hexameric mycobacterial proteasome ATPase (Mpa) recruits pupylated protein substrates via interactions between amino-terminal coiled-coils in Mpa monomers and the degradation tag Pup. However, it is unclear how Mpa rings interact with a proteasome due to the presence of a carboxyl-terminal β-grasp domain unique to Mpa homologues that makes the interaction highly unstable. Here, we describe newly identified critical interactions between Mpa and 20S core proteasomes. Interestingly, the Mpa C-terminal GQYL motif binds the 20S core particle activation pocket differently than the same motif of the ATP-independent proteasome accessory factor PafE. We further found that the β-hairpin of the Mpa β-grasp domain interacts variably with the H0 helix on top of the 20S core particle via a series of ionic and hydrogen-bond interactions. Individually mutating several involved residues reduced Mpa-mediated protein degradation both in vitro and in vivo. IMPORTANCE The Pup-proteasome system in Mycobacterium tuberculosis is critical for this species to cause lethal infections in mice. Investigating the molecular mechanism of how the Mpa ATPase recruits and unfolds pupylated substrates to the 20S proteasomal core particle for degradation will be essential to fully understand how degradation is regulated, and the structural information we report may be useful for the development of new tuberculosis chemotherapies.
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14
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Thellung S, Corsaro A, Dellacasagrande I, Nizzari M, Zambito M, Florio T. Proteostasis unbalance in prion diseases: Mechanisms of neurodegeneration and therapeutic targets. Front Neurosci 2022; 16:966019. [PMID: 36148145 PMCID: PMC9485628 DOI: 10.3389/fnins.2022.966019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 08/05/2022] [Indexed: 01/18/2023] Open
Abstract
Transmissible spongiform encephalopathies (TSEs), or prion diseases, are progressive neurodegenerative disorders of the central nervous system that affect humans and animals as sporadic, inherited, and infectious forms. Similarly to Alzheimer's disease and other neurodegenerative disorders, any attempt to reduce TSEs' lethality or increase the life expectancy of affected individuals has been unsuccessful. Typically, the onset of symptoms anticipates the fatal outcome of less than 1 year, although it is believed to be the consequence of a decades-long process of neuronal death. The duration of the symptoms-free period represents by itself a major obstacle to carry out effective neuroprotective therapies. Prions, the infectious entities of TSEs, are composed of a protease-resistant protein named prion protein scrapie (PrPSc) from the prototypical TSE form that afflicts ovines. PrPSc misfolding from its physiological counterpart, cellular prion protein (PrPC), is the unifying pathogenic trait of all TSEs. PrPSc is resistant to intracellular turnover and undergoes amyloid-like fibrillation passing through the formation of soluble dimers and oligomers, which are likely the effective neurotoxic entities. The failure of PrPSc removal is a key pathogenic event that defines TSEs as proteopathies, likewise other neurodegenerative disorders, including Alzheimer's, Parkinson's, and Huntington's disease, characterized by alteration of proteostasis. Under physiological conditions, protein quality control, led by the ubiquitin-proteasome system, and macroautophagy clears cytoplasm from improperly folded, redundant, or aggregation-prone proteins. There is evidence that both of these crucial homeostatic pathways are impaired during the development of TSEs, although it is still unclear whether proteostasis alteration facilitates prion protein misfolding or, rather, PrPSc protease resistance hampers cytoplasmic protein quality control. This review is aimed to critically analyze the most recent advancements in the cause-effect correlation between PrPC misfolding and proteostasis alterations and to discuss the possibility that pharmacological restoring of ubiquitin-proteasomal competence and stimulation of autophagy could reduce the intracellular burden of PrPSc and ameliorate the severity of prion-associated neurodegeneration.
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Affiliation(s)
- Stefano Thellung
- Section of Pharmacology, Department of Internal Medicine (DiMI), University of Genova, Genova, Italy
| | - Alessandro Corsaro
- Section of Pharmacology, Department of Internal Medicine (DiMI), University of Genova, Genova, Italy
| | - Irene Dellacasagrande
- Section of Pharmacology, Department of Internal Medicine (DiMI), University of Genova, Genova, Italy
| | - Mario Nizzari
- Section of Pharmacology, Department of Internal Medicine (DiMI), University of Genova, Genova, Italy
| | - Martina Zambito
- Section of Pharmacology, Department of Internal Medicine (DiMI), University of Genova, Genova, Italy
| | - Tullio Florio
- Section of Pharmacology, Department of Internal Medicine (DiMI), University of Genova, Genova, Italy
- IRCCS Ospedale Policlinico San Martino, Genova, Italy
- *Correspondence: Tullio Florio
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15
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Crystal structure of the Ate1 arginyl-tRNA-protein transferase and arginylation of N-degron substrates. Proc Natl Acad Sci U S A 2022; 119:e2209597119. [PMID: 35878037 PMCID: PMC9351520 DOI: 10.1073/pnas.2209597119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
N-degron pathways are proteolytic systems that target proteins bearing N-terminal (Nt) degradation signals (degrons) called N-degrons. Nt-Arg of a protein is among Nt-residues that can be recognized as destabilizing ones by the Arg/N-degron pathway. A proteolytic cleavage of a protein can generate Arg at the N terminus of a resulting C-terminal (Ct) fragment either directly or after Nt-arginylation of that Ct-fragment by the Ate1 arginyl-tRNA-protein transferase (R-transferase), which uses Arg-tRNAArg as a cosubstrate. Ate1 can Nt-arginylate Nt-Asp, Nt-Glu, and oxidized Nt-Cys* (Cys-sulfinate or Cys-sulfonate) of proteins or short peptides. Ate1 genes of fungi, animals, and plants have been cloned decades ago, but a three-dimensional structure of Ate1 remained unknown. A detailed mechanism of arginylation is unknown as well. We describe here the crystal structure of the Ate1 R-transferase from the budding yeast Kluyveromyces lactis. The 58-kDa R-transferase comprises two domains that recognize, together, an acidic Nt-residue of an acceptor substrate, the Arg residue of Arg-tRNAArg, and a 3'-proximal segment of the tRNAArg moiety. The enzyme's active site is located, at least in part, between the two domains. In vitro and in vivo arginylation assays with site-directed Ate1 mutants that were suggested by structural results yielded inferences about specific binding sites of Ate1. We also analyzed the inhibition of Nt-arginylation activity of Ate1 by hemin (Fe3+-heme), and found that hemin induced the previously undescribed disulfide-mediated oligomerization of Ate1. Together, these results advance the understanding of R-transferase and the Arg/N-degron pathway.
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16
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Enenkel C, Kang RW, Wilfling F, Ernst OP. Intracellular localization of the proteasome in response to stress conditions. J Biol Chem 2022; 298:102083. [PMID: 35636514 PMCID: PMC9218506 DOI: 10.1016/j.jbc.2022.102083] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 05/13/2022] [Accepted: 05/16/2022] [Indexed: 12/15/2022] Open
Abstract
The ubiquitin–proteasome system fulfills an essential role in regulating protein homeostasis by spatially and temporally controlling proteolysis in an ATP- and ubiquitin-dependent manner. However, the localization of proteasomes is highly variable under diverse cellular conditions. In yeast, newly synthesized proteasomes are primarily localized to the nucleus during cell proliferation. Yeast proteasomes are transported into the nucleus through the nuclear pore either as immature subcomplexes or as mature enzymes via adapter proteins Sts1 and Blm10, while in mammalian cells, postmitotic uptake of proteasomes into the nucleus is mediated by AKIRIN2, an adapter protein essentially required for nuclear protein degradation. Stressful growth conditions and the reversible halt of proliferation, that is quiescence, are associated with a decline in ATP and the reorganization of proteasome localization. Cellular stress leads to proteasome accumulation in membraneless granules either in the nucleus or in the cytoplasm. In quiescence, yeast proteasomes are sequestered in an ubiquitin-dependent manner into motile and reversible proteasome storage granules in the cytoplasm. In cancer cells, upon amino acid deprivation, heat shock, osmotic stress, oxidative stress, or the inhibition of either proteasome activity or nuclear export, reversible proteasome foci containing polyubiquitinated substrates are formed by liquid–liquid phase separation in the nucleus. In this review, we summarize recent literature revealing new links between nuclear transport, ubiquitin signaling, and the intracellular organization of proteasomes during cellular stress conditions.
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Affiliation(s)
- Cordula Enenkel
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.
| | - Ryu Won Kang
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Florian Wilfling
- Mechanisms of Cellular Quality Control, Max-Planck-Institute of Biophysics, Frankfurt, Germany
| | - Oliver P Ernst
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada; Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
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17
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Behl T, Kumar S, Althafar ZM, Sehgal A, Singh S, Sharma N, Badavath VN, Yadav S, Bhatia S, Al-Harrasi A, Almoshari Y, Almikhlafi MA, Bungau S. Exploring the Role of Ubiquitin-Proteasome System in Parkinson's Disease. Mol Neurobiol 2022; 59:4257-4273. [PMID: 35505049 DOI: 10.1007/s12035-022-02851-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 04/25/2022] [Indexed: 02/06/2023]
Abstract
Over the last decade, researchers have discovered that a group of apparently unrelated neurodegenerative disorders, such as Parkinson's disease, have remarkable cellular and molecular biology similarities. Protein misfolding and aggregation are involved in all of the neurodegenerative conditions; as a result, inclusion bodies aggregation starts in the cells. Chaperone proteins and ubiquitin (26S proteasome's proteolysis signal), which aid in refolding misfolded proteins, are frequently found in these aggregates. The discovery of disease-causing gene alterations that code for multiple ubiquitin-proteasome pathway proteins in Parkinson's disease has strengthened the relationship between the ubiquitin-proteasome system and neurodegeneration. The specific molecular linkages between these systems and pathogenesis, on the other hand, are unknown and controversial. We outline the current level of knowledge in this article, focusing on important unanswered problems.
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Affiliation(s)
- Tapan Behl
- Chitkara College of Pharmacy, Chitkara University, Punjab, India.
| | - Sachin Kumar
- Chitkara College of Pharmacy, Chitkara University, Punjab, India
| | - Ziyad M Althafar
- Department of Medical Laboratories Sciences, College of Applied Medical Sciences in Alquwayiyah, Shaqra University, Riyadh, Saudi Arabia
| | - Aayush Sehgal
- Chitkara College of Pharmacy, Chitkara University, Punjab, India
| | - Sukhbir Singh
- Chitkara College of Pharmacy, Chitkara University, Punjab, India
| | - Neelam Sharma
- Chitkara College of Pharmacy, Chitkara University, Punjab, India
| | | | - Shivam Yadav
- Yashraj Institute of Pharmacy, Uttar Pradesh, India
| | - Saurabh Bhatia
- Natural & Medical Sciences Research Center, University of Nizwa, Nizwa, Oman.,School of Health Science, University of Petroleum and Energy Studies, Dehradun, Uttarakhand, India
| | - Ahmed Al-Harrasi
- Natural & Medical Sciences Research Center, University of Nizwa, Nizwa, Oman
| | - Yosif Almoshari
- Department of Pharmaceutics, College of Pharmacy, Jazan University, Jazan, Saudi Arabia
| | - Mohannad A Almikhlafi
- Department of Pharmacology and Toxicology, College of Pharmacy, Taibha University, Madinah, Saudi Arabia
| | - Simona Bungau
- Department of Pharmacy, Faculty of Medicine and Pharmacy, University of Oradea, Oradea, Romania
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18
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Hung KYS, Klumpe S, Eisele MR, Elsasser S, Tian G, Sun S, Moroco JA, Cheng TC, Joshi T, Seibel T, Van Dalen D, Feng XH, Lu Y, Ovaa H, Engen JR, Lee BH, Rudack T, Sakata E, Finley D. Allosteric control of Ubp6 and the proteasome via a bidirectional switch. Nat Commun 2022; 13:838. [PMID: 35149681 PMCID: PMC8837689 DOI: 10.1038/s41467-022-28186-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Accepted: 01/10/2022] [Indexed: 11/09/2022] Open
Abstract
The proteasome recognizes ubiquitinated proteins and can also edit ubiquitin marks, allowing substrates to be rejected based on ubiquitin chain topology. In yeast, editing is mediated by deubiquitinating enzyme Ubp6. The proteasome activates Ubp6, whereas Ubp6 inhibits the proteasome through deubiquitination and a noncatalytic effect. Here, we report cryo-EM structures of the proteasome bound to Ubp6, based on which we identify mutants in Ubp6 and proteasome subunit Rpt1 that abrogate Ubp6 activation. The Ubp6 mutations define a conserved region that we term the ILR element. The ILR is found within the BL1 loop, which obstructs the catalytic groove in free Ubp6. Rpt1-ILR interaction opens the groove by rearranging not only BL1 but also a previously undescribed network of three interconnected active-site-blocking loops. Ubp6 activation and noncatalytic proteasome inhibition are linked in that they are eliminated by the same mutations. Ubp6 and ubiquitin together drive proteasomes into a unique conformation associated with proteasome inhibition. Thus, a multicomponent allosteric switch exerts simultaneous control over both Ubp6 and the proteasome.
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Affiliation(s)
| | - Sven Klumpe
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
| | - Markus R Eisele
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
| | - Suzanne Elsasser
- Department of Cell Biology, Harvard Medical School, Boston, MA, 02115, USA
| | - Geng Tian
- Department of Cell Biology, Harvard Medical School, Boston, MA, 02115, USA
| | - Shuangwu Sun
- Department of Cell Biology, Harvard Medical School, Boston, MA, 02115, USA.,Life Sciences Institute (LSI), Zhejiang University, Hangzhou, 310058, China
| | - Jamie A Moroco
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, 02115, USA
| | - Tat Cheung Cheng
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany.,Institute for Auditory Neuroscience, University Medical Center Göttingen, 37077, Göttingen, Germany
| | - Tapan Joshi
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
| | - Timo Seibel
- Department of Cell Biology, Harvard Medical School, Boston, MA, 02115, USA
| | - Duco Van Dalen
- Leiden University Medical Center, Einthovenweg 20, 2333, Leiden, ZC, the Netherlands
| | - Xin-Hua Feng
- Life Sciences Institute (LSI), Zhejiang University, Hangzhou, 310058, China
| | - Ying Lu
- Department of Systems Biology, Harvard Medical School, Boston, MA, 02115, USA
| | - Huib Ovaa
- Leiden University Medical Center, Einthovenweg 20, 2333, Leiden, ZC, the Netherlands
| | - John R Engen
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, 02115, USA
| | - Byung-Hoon Lee
- Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, 42988, Korea.
| | - Till Rudack
- Biospectroscopy, Center for Protein Diagnostics (PRODI), Ruhr University Bochum, 44801, Bochum, Germany. .,Department of Biophysics, Ruhr University Bochum, 44801, Bochum, Germany.
| | - Eri Sakata
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany. .,Institute for Auditory Neuroscience, University Medical Center Göttingen, 37077, Göttingen, Germany. .,Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells (MBExC), University of Goettingen, 37073, Göttingen, Germany.
| | - Daniel Finley
- Department of Cell Biology, Harvard Medical School, Boston, MA, 02115, USA.
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19
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do Patrocinio AB, Rodrigues V, Guidi Magalhães L. P53: Stability from the Ubiquitin-Proteasome System and Specific 26S Proteasome Inhibitors. ACS OMEGA 2022; 7:3836-3843. [PMID: 35155881 PMCID: PMC8829948 DOI: 10.1021/acsomega.1c04726] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Accepted: 12/17/2021] [Indexed: 06/14/2023]
Abstract
Protein p53 is degraded by the 26S proteasome, a protein complex that breaks down cellular proteins. Degradation begins with activation of the protein ubiquitin (Ub) by the ubiquitin-activating E1 enzymes, ubiquitin-conjugating E2 enzymes, and ubiquitin E3 ligases, linking Ub or the polyubiquitin chain to p53 and marking it for degradation by the 26S proteasome. E3 ubiquitin ligases participate in this process and regulate p53 stability. There are compounds that inhibit the 26S proteasome and interfere at the p53 level, and some of these inhibitors are used to treat cancer and other diseases and can stabilize tumor suppressor proteins through the p53 pathway. This review discusses how the ubiquitin-proteasome system, p53, and these compounds are related.
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Affiliation(s)
- Andressa Barban do Patrocinio
- Research
Group on Natural Products (Center for Research in Sciences and Technology), Universidade de Franca, Av. Dr. Armando de Sales Oliveira, 201 - Parque
Universitário, Franca, São Paulo 14404-600, Brazil
| | - Vanderlei Rodrigues
- Department
of Biochemistry and Immunology, Ribeirão Preto Medical School, Universidade de São Paulo, Avenida Bandeirantes 3900, Ribeirão Preto, São Paulo 14049-900, Brazil
| | - Lizandra Guidi Magalhães
- Research
Group on Natural Products (Center for Research in Sciences and Technology), Universidade de Franca, Av. Dr. Armando de Sales Oliveira, 201 - Parque
Universitário, Franca, São Paulo 14404-600, Brazil
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20
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Kisselev AF. Site-Specific Proteasome Inhibitors. Biomolecules 2021; 12:54. [PMID: 35053202 PMCID: PMC8773591 DOI: 10.3390/biom12010054] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 12/22/2021] [Accepted: 12/27/2021] [Indexed: 12/14/2022] Open
Abstract
Proteasome is a multi-subunit protein degradation machine, which plays a key role in the maintenance of protein homeostasis and, through degradation of regulatory proteins, in the regulation of numerous cell functions. Proteasome inhibitors are essential tools for biomedical research. Three proteasome inhibitors, bortezomib, carfilzomib, and ixazomib are approved by the FDA for the treatment of multiple myeloma; another inhibitor, marizomib, is undergoing clinical trials. The proteolytic core of the proteasome has three pairs of active sites, β5, β2, and β1. All clinical inhibitors and inhibitors that are widely used as research tools (e.g., epoxomicin, MG-132) inhibit multiple active sites and have been extensively reviewed in the past. In the past decade, highly specific inhibitors of individual active sites and the distinct active sites of the lymphoid tissue-specific immunoproteasome have been developed. Here, we provide a comprehensive review of these site-specific inhibitors of mammalian proteasomes and describe their utilization in the studies of the biology of the active sites and their roles as drug targets for the treatment of different diseases.
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Affiliation(s)
- Alexei F Kisselev
- Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, AL 36849, USA
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21
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Tomita T. Structural and biochemical elements of efficiently degradable proteasome substrates. J Biochem 2021; 171:261-268. [PMID: 34967398 DOI: 10.1093/jb/mvab157] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 12/14/2021] [Indexed: 11/14/2022] Open
Abstract
Most regulated proteolysis in cells is conducted by the ubiquitin-proteasome system, in which proteins to be eliminated are selected through multiple steps to achieve high specificity. The large protease complex proteasome binds to ubiquitin molecules that are attached to the substrate and further interacts with a disordered region in the target to initiate unfolding for degradation. Recent studies have expanded our view of the complexity of ubiquitination as well as the details of substrate engagement by the proteasome and at the same time have suggested the characteristics of substrates that are susceptible to proteasomal degradation. Here, I review some destabilizing elements of proteasome substrates with particular attention to ubiquitination, initiation region and stability against unfolding and discuss their interplay to determine the substrate stability. A spatial perspective is important to understand the mechanism of action of proteasomal degradation, which may be critical for drug development targeting the ubiquitin-proteasome system including targeted protein degradation.
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Affiliation(s)
- Takuya Tomita
- Protein Metabolism Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
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22
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Aminopeptidases trim Xaa-Pro proteins, initiating their degradation by the Pro/N-degron pathway. Proc Natl Acad Sci U S A 2021; 118:2115430118. [PMID: 34663735 DOI: 10.1073/pnas.2115430118] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/12/2021] [Indexed: 12/26/2022] Open
Abstract
N-degron pathways are proteolytic systems that recognize proteins bearing N-terminal (Nt) degradation signals (degrons) called N-degrons. Our previous work identified Gid4 as a recognition component (N-recognin) of the Saccharomyces cerevisiae proteolytic system termed the proline (Pro)/N-degron pathway. Gid4 is a subunit of the oligomeric glucose-induced degradation (GID) ubiquitin ligase. Gid4 targets proteins through the binding to their Nt-Pro residue. Gid4 is also required for degradation of Nt-Xaa-Pro (Xaa is any amino acid residue) proteins such as Nt-[Ala-Pro]-Aro10 and Nt-[Ser-Pro]-Pck1, with Pro at position 2. Here, we show that specific aminopeptidases function as components of the Pro/N-degron pathway by removing Nt-Ala or Nt-Ser and yielding Nt-Pro, which can be recognized by Gid4-GID. Nt-Ala is removed by the previously uncharacterized aminopeptidase Fra1. The enzymatic activity of Fra1 is shown to be essential for the GID-dependent degradation of Nt-[Ala-Pro]-Aro10. Fra1 can also trim Nt-[Ala-Pro-Pro-Pro] (stopping immediately before the last Pro) and thereby can target for degradation a protein bearing this Nt sequence. Nt-Ser is removed largely by the mitochondrial/cytosolic/nuclear aminopeptidase Icp55. These advances are relevant to eukaryotes from fungi to animals and plants, as Fra1, Icp55, and the GID ubiquitin ligase are conserved in evolution. In addition to discovering the mechanism of targeting of Xaa-Pro proteins, these insights have also expanded the diversity of substrates of the Pro/N-degron pathway.
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23
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Popova B, Galka D, Häffner N, Wang D, Schmitt K, Valerius O, Knop M, Braus GH. α-Synuclein Decreases the Abundance of Proteasome Subunits and Alters Ubiquitin Conjugates in Yeast. Cells 2021; 10:cells10092229. [PMID: 34571878 PMCID: PMC8468666 DOI: 10.3390/cells10092229] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 08/25/2021] [Accepted: 08/25/2021] [Indexed: 01/18/2023] Open
Abstract
Parkinson’s disease (PD) is the most prevalent movement disorder characterized with loss of dopaminergic neurons in the brain. One of the pathological hallmarks of the disease is accumulation of aggregated α-synuclein (αSyn) in cytoplasmic Lewy body inclusions that indicates significant dysfunction of protein homeostasis in PD. Accumulation is accompanied with highly elevated S129 phosphorylation, suggesting that this posttranslational modification is linked to pathogenicity and altered αSyn inclusion dynamics. To address the role of S129 phosphorylation on protein dynamics further we investigated the wild type and S129A variants using yeast and a tandem fluorescent timer protein reporter approach to monitor protein turnover and stability. Overexpression of both variants leads to inhibited yeast growth. Soluble S129A is more stable and additional Y133F substitution permits αSyn degradation in a phosphorylation-independent manner. Quantitative cellular proteomics revealed significant αSyn-dependent disturbances of the cellular protein homeostasis, which are increased upon S129 phosphorylation. Disturbances are characterized by decreased abundance of the ubiquitin-dependent protein degradation machinery. Biotin proximity labelling revealed that αSyn interacts with the Rpt2 base subunit. Proteasome subunit depletion by reducing the expression of the corresponding genes enhances αSyn toxicity. Our studies demonstrate that turnover of αSyn and depletion of the proteasome pool correlate in a complex relationship between altered proteasome composition and increased αSyn toxicity.
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Affiliation(s)
- Blagovesta Popova
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany; (D.G.); (N.H.); (D.W.); (K.S.); (O.V.)
- Correspondence: (B.P.); (G.H.B.)
| | - Dajana Galka
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany; (D.G.); (N.H.); (D.W.); (K.S.); (O.V.)
| | - Nicola Häffner
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany; (D.G.); (N.H.); (D.W.); (K.S.); (O.V.)
| | - Dan Wang
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany; (D.G.); (N.H.); (D.W.); (K.S.); (O.V.)
| | - Kerstin Schmitt
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany; (D.G.); (N.H.); (D.W.); (K.S.); (O.V.)
| | - Oliver Valerius
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany; (D.G.); (N.H.); (D.W.); (K.S.); (O.V.)
| | - Michael Knop
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg University, 69120 Heidelberg, Germany;
| | - Gerhard H. Braus
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany; (D.G.); (N.H.); (D.W.); (K.S.); (O.V.)
- Correspondence: (B.P.); (G.H.B.)
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24
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Nishimura Y, Musa I, Holm L, Lai YC. Recent advances in measuring and understanding the regulation of exercise-mediated protein degradation in skeletal muscle. Am J Physiol Cell Physiol 2021; 321:C276-C287. [PMID: 34038244 DOI: 10.1152/ajpcell.00115.2021] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Skeletal muscle protein turnover plays a crucial role in controlling muscle mass and protein quality control, including sarcomeric (structural and contractile) proteins. Protein turnover is a dynamic and continual process of protein synthesis and degradation. The ubiquitin proteasome system (UPS) is a key degradative system for protein degradation and protein quality control in skeletal muscle. UPS-mediated protein quality control is known to be impaired in aging and diseases. Exercise is a well-recognized, nonpharmacological approach to promote muscle protein turnover rates. Over the past decades, we have acquired substantial knowledge of molecular mechanisms of muscle protein synthesis after exercise. However, there have been considerable gaps in the mechanisms of how muscle protein degradation is regulated at the molecular level. The main challenge to understand muscle protein degradation is due in part to the lack of solid stable isotope tracer methodology to measure muscle protein degradation rate. Understanding the mechanisms of UPS with the concomitant measurement of protein degradation rate in skeletal muscle will help identify novel therapeutic strategies to ameliorate impaired protein turnover and protein quality control in aging and diseases. Thus, the goal of this present review was to highlight how recent advances in the field may help improve our understanding of exercise-mediated protein degradation. We discuss 1) the emerging roles of protein phosphorylation and ubiquitylation modifications in regulating proteasome-mediated protein degradation after exercise and 2) methodological advances to measure in vivo myofibrillar protein degradation rate using stable isotope tracer methods.
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Affiliation(s)
- Yusuke Nishimura
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Ibrahim Musa
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Lars Holm
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
- MRC Versus Arthritis Centre for Musculoskeletal Ageing Research, University of Birmingham, Birmingham, United Kingdom
| | - Yu-Chiang Lai
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
- MRC Versus Arthritis Centre for Musculoskeletal Ageing Research, University of Birmingham, Birmingham, United Kingdom
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom
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25
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Joyce S, Ternette N. Know thy immune self and non-self: Proteomics informs on the expanse of self and non-self, and how and where they arise. Proteomics 2021; 21:e2000143. [PMID: 34310018 PMCID: PMC8865197 DOI: 10.1002/pmic.202000143] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 06/30/2021] [Accepted: 07/19/2021] [Indexed: 12/30/2022]
Abstract
T cells play an important role in the adaptive immune response to a variety of infections and cancers. Initiation of a T cell mediated immune response requires antigen recognition in a process termed MHC (major histocompatibility complex) restri ction. A T cell antigen is a composite structure made up of a peptide fragment bound within the antigen‐binding groove of an MHC‐encoded class I or class II molecule. Insight into the precise composition and biology of self and non‐self immunopeptidomes is essential to harness T cell mediated immunity to prevent, treat, or cure infectious diseases and cancers. T cell antigen discovery is an arduous task! The pioneering work in the early 1990s has made large‐scale T cell antigen discovery possible. Thus, advancements in mass spectrometry coupled with proteomics and genomics technologies make possible T cell antigen discovery with ease, accuracy, and sensitivity. Yet we have only begun to understand the breadth and the depth of self and non‐self immunopeptidomes because the molecular biology of the cell continues to surprise us with new secrets directly related to the source, and the processing and presentation of MHC ligands. Focused on MHC class I molecules, this review, therefore, provides a brief historic account of T cell antigen discovery and, against a backdrop of key advances in molecular cell biologic processes, elaborates on how proteogenomics approaches have revolutionised the field.
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Affiliation(s)
- Sebastian Joyce
- Department of Veterans Affairs, Tennessee Valley Healthcare System and the Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Nicola Ternette
- Centre for Cellular and Molecular Physiology, Nuffield Department of Medicine, University of Oxford, Oxford, UK
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26
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Kyca T, Pavlíková L, Boháčová V, Mišák A, Poturnayová A, Breier A, Sulová Z, Šereš M. Insight into Bortezomib Focusing on Its Efficacy against P-gp-Positive MDR Leukemia Cells. Int J Mol Sci 2021; 22:ijms22115504. [PMID: 34071136 PMCID: PMC8197160 DOI: 10.3390/ijms22115504] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/12/2021] [Accepted: 05/21/2021] [Indexed: 02/06/2023] Open
Abstract
In this paper, we compared the effects of bortezomib on L1210 (S) cells with its effects on P-glycoprotein (P-gp)-positive variant S cells, which expressed P-gp either after selection with vincristine (R cells) or after transfection with a human gene encoding P-gp (T cells). Bortezomib induced the death-related effects in the S, R, and T cells at concentrations not exceeding 10 nM. Bortezomib-induced cell cycle arrest in the G2/M phase was more pronounced in the S cells than in the R or T cells and was related to the expression levels of cyclins, cyclin-dependent kinases, and their inhibitors. We also observed an increase in the level of polyubiquitinated proteins (via K48-linkage) and a decrease in the gene expression of some deubiquitinases after treatment with bortezomib. Resistant cells expressed higher levels of genes encoding 26S proteasome components and the chaperone HSP90, which is involved in 26S proteasome assembly. After 4 h of preincubation, bortezomib induced a more pronounced depression of proteasome activity in S cells than in R or T cells. However, none of these changes alone or in combination sufficiently suppressed the sensitivity of R or T cells to bortezomib, which remained at a level similar to that of S cells.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics
- ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism
- Animals
- Antineoplastic Agents/pharmacology
- Bortezomib/pharmacology
- Cell Cycle/drug effects
- Cell Division
- Cell Line, Tumor
- Deubiquitinating Enzymes
- Drug Resistance, Multiple/drug effects
- Drug Resistance, Neoplasm/drug effects
- Fluoresceins/metabolism
- Gene Expression Regulation, Neoplastic/drug effects
- Genes, cdc/drug effects
- Humans
- Inhibitory Concentration 50
- Leukemia, Lymphoid/genetics
- Leukemia, Lymphoid/metabolism
- Leukemia, Lymphoid/pathology
- Mice
- Neoplasm Proteins/genetics
- Neoplasm Proteins/metabolism
- Protease Inhibitors/pharmacology
- Proteasome Endopeptidase Complex/drug effects
- Proteasome Endopeptidase Complex/metabolism
- RNA, Messenger/biosynthesis
- RNA, Neoplasm/biosynthesis
- Recombinant Proteins/metabolism
- Transcription, Genetic/drug effects
- Ubiquitinated Proteins/metabolism
- Vincristine/pharmacology
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Affiliation(s)
- Tomáš Kyca
- Institute of Molecular Physiology and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Dúbravská cesta 9, 84505 Bratislava, Slovakia; (T.K.); (L.P.); (V.B.); (A.P.)
| | - Lucia Pavlíková
- Institute of Molecular Physiology and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Dúbravská cesta 9, 84505 Bratislava, Slovakia; (T.K.); (L.P.); (V.B.); (A.P.)
- Institute of Zoology, Slovak Academy of Sciences, Dúbravská cesta 9, 84506 Bratislava, Slovakia
| | - Viera Boháčová
- Institute of Molecular Physiology and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Dúbravská cesta 9, 84505 Bratislava, Slovakia; (T.K.); (L.P.); (V.B.); (A.P.)
| | - Anton Mišák
- Institute for Clinical and Translational Research, Biomedical Research Center, Slovak Academy of Sciences, Dúbravská cesta 9, 84505 Bratislava, Slovakia;
| | - Alexandra Poturnayová
- Institute of Molecular Physiology and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Dúbravská cesta 9, 84505 Bratislava, Slovakia; (T.K.); (L.P.); (V.B.); (A.P.)
| | - Albert Breier
- Institute of Molecular Physiology and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Dúbravská cesta 9, 84505 Bratislava, Slovakia; (T.K.); (L.P.); (V.B.); (A.P.)
- Institute of Biochemistry and Microbiology, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského 9, 81237 Bratislava 1, Slovakia
- Correspondence: (A.B.); (Z.S.); (M.Š.); Tel.: +421-2-593-25-514 or +421-918-674-514 (A.B.); +421-2-3229-5510 (Z.S.)
| | - Zdena Sulová
- Institute of Molecular Physiology and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Dúbravská cesta 9, 84505 Bratislava, Slovakia; (T.K.); (L.P.); (V.B.); (A.P.)
- Correspondence: (A.B.); (Z.S.); (M.Š.); Tel.: +421-2-593-25-514 or +421-918-674-514 (A.B.); +421-2-3229-5510 (Z.S.)
| | - Mário Šereš
- Institute of Molecular Physiology and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Dúbravská cesta 9, 84505 Bratislava, Slovakia; (T.K.); (L.P.); (V.B.); (A.P.)
- Institute of Zoology, Slovak Academy of Sciences, Dúbravská cesta 9, 84506 Bratislava, Slovakia
- Correspondence: (A.B.); (Z.S.); (M.Š.); Tel.: +421-2-593-25-514 or +421-918-674-514 (A.B.); +421-2-3229-5510 (Z.S.)
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Proteasome in action: substrate degradation by the 26S proteasome. Biochem Soc Trans 2021; 49:629-644. [PMID: 33729481 PMCID: PMC8106498 DOI: 10.1042/bst20200382] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 02/22/2021] [Accepted: 02/25/2021] [Indexed: 12/16/2022]
Abstract
Ubiquitination is the major criteria for the recognition of a substrate-protein by the 26S proteasome. Additionally, a disordered segment on the substrate — either intrinsic or induced — is critical for proteasome engagement. The proteasome is geared to interact with both of these substrate features and prepare it for degradation. To facilitate substrate accessibility, resting proteasomes are characterised by a peripheral distribution of ubiquitin receptors on the 19S regulatory particle (RP) and a wide-open lateral surface on the ATPase ring. In this substrate accepting state, the internal channel through the ATPase ring is discontinuous, thereby obstructing translocation of potential substrates. The binding of the conjugated ubiquitin to the ubiquitin receptors leads to contraction of the 19S RP. Next, the ATPases engage the substrate at a disordered segment, energetically unravel the polypeptide and translocate it towards the 20S catalytic core (CP). In this substrate engaged state, Rpn11 is repositioned at the pore of the ATPase channel to remove remaining ubiquitin modifications and accelerate translocation. C-termini of five of the six ATPases insert into corresponding lysine-pockets on the 20S α-ring to complete 20S CP gate opening. In the resulting substrate processing state, the ATPase channel is fully contiguous with the translocation channel into the 20S CP, where the substrate is proteolyzed. Complete degradation of a typical ubiquitin-conjugate takes place over a few tens of seconds while hydrolysing tens of ATP molecules in the process (50 kDa/∼50 s/∼80ATP). This article reviews recent insight into biochemical and structural features that underlie substrate recognition and processing by the 26S proteasome.
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Qin X, Liu J, Pan D, Ma W, Cheng P, Jin F. Corilagin induces human glioblastoma U251 cell apoptosis by impeding activity of (immuno)proteasome. Oncol Rep 2021; 45:34. [PMID: 33649855 PMCID: PMC7905533 DOI: 10.3892/or.2021.7985] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 01/28/2021] [Indexed: 11/29/2022] Open
Abstract
Glioma is a type of common primary intracranial tumor, which is difficult to treat. It has been confirmed by research that corilagin (the primary active constituent of the matsumura leafflower herb) has significant antitumor effect. In particular, our previous research demonstrated that corilagin effectively promotes apoptosis of glioma U251 cells and has a synergistic effect when used with temozolomide. However, the mechanism by which corilagin causes apoptosis in U251 cells has yet to be investigated. Proteasomes are catalytic centers of the ubiquitin-proteasome system, which is the major protein degradation pathway in eukaryotic cells; they are primarily responsible for the degradation of signal molecules, tumor suppressors, cyclins and apoptosis inhibitors and serve an important role in tumor cell proliferation and apoptosis. The present study investigated the pro-apoptotic effect of corilagin on glioma U251 cells and confirmed that decreased proteasome activity and expression levels serve an important role in corilagin-induced U251 cell apoptosis.
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Affiliation(s)
- Xianyun Qin
- Medical Research Center, Affiliated Hospital of Jining Medical University, Jining Medical University, Jining, Shandong 272029, P.R. China
| | - Jilan Liu
- Medical Research Center, Affiliated Hospital of Jining Medical University, Jining Medical University, Jining, Shandong 272029, P.R. China
| | - Dongfeng Pan
- Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA 22908, USA
| | - Wenyuan Ma
- Department of Neurosurgery, Affiliated Hospital of Jining Medical University and Shandong Provincial Key Laboratory of Stem Cells and Neuro‑Oncology, Jining, Shandong 272029, P.R. China
| | - Panpan Cheng
- Department of Hematology Laboratory, Affiliated Hospital of Jining Medical University, Jining Medical University, Jining, Shandong 272029, P.R. China
| | - Feng Jin
- Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA 22908, USA
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29
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Cascio P. PA28γ: New Insights on an Ancient Proteasome Activator. Biomolecules 2021; 11:228. [PMID: 33562807 PMCID: PMC7915322 DOI: 10.3390/biom11020228] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2021] [Revised: 02/02/2021] [Accepted: 02/03/2021] [Indexed: 02/06/2023] Open
Abstract
PA28 (also known as 11S, REG or PSME) is a family of proteasome regulators whose members are widely present in many of the eukaryotic supergroups. In jawed vertebrates they are represented by three paralogs, PA28α, PA28β, and PA28γ, which assemble as heptameric hetero (PA28αβ) or homo (PA28γ) rings on one or both extremities of the 20S proteasome cylindrical structure. While they share high sequence and structural similarities, the three isoforms significantly differ in terms of their biochemical and biological properties. In fact, PA28α and PA28β seem to have appeared more recently and to have evolved very rapidly to perform new functions that are specifically aimed at optimizing the process of MHC class I antigen presentation. In line with this, PA28αβ favors release of peptide products by proteasomes and is particularly suited to support adaptive immune responses without, however, affecting hydrolysis rates of protein substrates. On the contrary, PA28γ seems to be a slow-evolving gene that is most similar to the common ancestor of the PA28 activators family, and very likely retains its original functions. Notably, PA28γ has a prevalent nuclear localization and is involved in the regulation of several essential cellular processes including cell growth and proliferation, apoptosis, chromatin structure and organization, and response to DNA damage. In striking contrast with the activity of PA28αβ, most of these diverse biological functions of PA28γ seem to depend on its ability to markedly enhance degradation rates of regulatory protein by 20S proteasome. The present review will focus on the molecular mechanisms and biochemical properties of PA28γ, which are likely to account for its various and complex biological functions and highlight the common features with the PA28αβ paralog.
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Affiliation(s)
- Paolo Cascio
- Department of Veterinary Sciences, University of Turin, Largo P. Braccini 2, 10095 Grugliasco, Italy
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