1
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Sharifi S, Yamamoto T, Zeug A, Elsner M, Avezov E, Mehmeti I. Non-esterified fatty acid palmitate facilitates oxidative endoplasmic reticulum stress and apoptosis of β-cells by upregulating ERO-1α expression. Redox Biol 2024; 73:103170. [PMID: 38692092 PMCID: PMC11070623 DOI: 10.1016/j.redox.2024.103170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Revised: 04/24/2024] [Accepted: 04/26/2024] [Indexed: 05/03/2024] Open
Abstract
Adipose tissue-derived non-esterified saturated long-chain fatty acid palmitate (PA) decisively contributes to β-cell demise in type 2 diabetes mellitus in part through the excessive generation of hydrogen peroxide (H2O2). The endoplasmic reticulum (ER) as the primary site of oxidative protein folding could represent a significant source of H2O2. Both ER-oxidoreductin-1 (ERO-1) isoenzymes, ERO-1α and ERO-1β, catalyse oxidative protein folding within the ER, generating equimolar amounts of H2O2 for every disulphide bond formed. However, whether ERO-1-derived H2O2 constitutes a potential source of cytotoxic luminal H2O2 under lipotoxic conditions is still unknown. Here, we demonstrate that both ERO-1 isoforms are expressed in pancreatic β-cells, but interestingly, PA only significantly induces ERO-1α. Its specific deletion significantly attenuates PA-mediated oxidative ER stress and subsequent β-cell death by decreasing PA-mediated ER-luminal and mitochondrial H2O2 accumulation, by counteracting the dysregulation of ER Ca2+ homeostasis, and by mitigating the reduction of mitochondrial membrane potential and lowered ATP content. Moreover, ablation of ERO-1α alleviated PA-induced hyperoxidation of the ER redox milieu. Importantly, ablation of ERO-1α did not affect the insulin secretory capacity, the unfolded protein response, or ER redox homeostasis under steady-state conditions. The involvement of ERO-1α-derived H2O2 in PA-mediated β-cell lipotoxicity was corroborated by the overexpression of a redox-active ERO-1α underscoring the proapoptotic activity of ERO-1α in pancreatic β-cells. Overall, our findings highlight the critical role of ERO-1α-derived H2O2 in lipotoxic ER stress and β-cell failure.
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Affiliation(s)
- Sarah Sharifi
- Institute of Clinical Biochemistry, Hannover Medical School, 30625, Hannover, Germany
| | - Tomoko Yamamoto
- Institute of Clinical Biochemistry, Hannover Medical School, 30625, Hannover, Germany
| | - Andre Zeug
- Institute for Neurophysiology, Hannover Medical School, 30625, Hannover, Germany
| | - Matthias Elsner
- Institute of Clinical Biochemistry, Hannover Medical School, 30625, Hannover, Germany
| | - Edward Avezov
- Department of Clinical Neurosciences and UK Dementia Research Institute, University of Cambridge, CB2 0AH Cambridge, UK
| | - Ilir Mehmeti
- Institute of Clinical Biochemistry, Hannover Medical School, 30625, Hannover, Germany.
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2
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Crapart CC, Scott ZC, Konno T, Sharma A, Parutto P, Bailey DMD, Westrate LM, Avezov E, Koslover EF. Luminal transport through intact endoplasmic reticulum limits the magnitude of localized Ca 2+ signals. Proc Natl Acad Sci U S A 2024; 121:e2312172121. [PMID: 38502705 PMCID: PMC10990089 DOI: 10.1073/pnas.2312172121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 02/09/2024] [Indexed: 03/21/2024] Open
Abstract
The endoplasmic reticulum (ER) forms an interconnected network of tubules stretching throughout the cell. Understanding how ER functionality relies on its structural organization is crucial for elucidating cellular vulnerability to ER perturbations, which have been implicated in several neuronal pathologies. One of the key functions of the ER is enabling Ca[Formula: see text] signaling by storing large quantities of this ion and releasing it into the cytoplasm in a spatiotemporally controlled manner. Through a combination of physical modeling and live-cell imaging, we demonstrate that alterations in ER shape significantly impact its ability to support efficient local Ca[Formula: see text] releases, due to hindered transport of luminal content within the ER. Our model reveals that rapid Ca[Formula: see text] release necessitates mobile luminal buffer proteins with moderate binding strength, moving through a well-connected network of ER tubules. These findings provide insight into the functional advantages of normal ER architecture, emphasizing its importance as a kinetically efficient intracellular Ca[Formula: see text] delivery system.
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Affiliation(s)
- Cécile C. Crapart
- UK Dementia Research Institute at the University of Cambridge, CambridgeCB2 0AH, United Kingdom
- Department of Clinical Neurosciences, School of Clinical Medicine, The University of Cambridge, CambridgeCB2 0AH, United Kingdom
| | | | - Tasuku Konno
- UK Dementia Research Institute at the University of Cambridge, CambridgeCB2 0AH, United Kingdom
- Department of Clinical Neurosciences, School of Clinical Medicine, The University of Cambridge, CambridgeCB2 0AH, United Kingdom
| | - Aman Sharma
- Department of Physics, University of California, San Diego, La Jolla, CA92130
| | - Pierre Parutto
- UK Dementia Research Institute at the University of Cambridge, CambridgeCB2 0AH, United Kingdom
- Department of Clinical Neurosciences, School of Clinical Medicine, The University of Cambridge, CambridgeCB2 0AH, United Kingdom
| | - David M. D. Bailey
- UK Dementia Research Institute at the University of Cambridge, CambridgeCB2 0AH, United Kingdom
- Department of Clinical Neurosciences, School of Clinical Medicine, The University of Cambridge, CambridgeCB2 0AH, United Kingdom
| | - Laura M. Westrate
- Department of Chemistry and Biochemistry, Calvin University, Grand Rapids, MI49546
| | - Edward Avezov
- UK Dementia Research Institute at the University of Cambridge, CambridgeCB2 0AH, United Kingdom
- Department of Clinical Neurosciences, School of Clinical Medicine, The University of Cambridge, CambridgeCB2 0AH, United Kingdom
| | - Elena F. Koslover
- Department of Physics, University of California, San Diego, La Jolla, CA92130
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3
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Lu M, Christensen CN, Weber JM, Konno T, Läubli NF, Scherer KM, Avezov E, Lio P, Lapkin AA, Kaminski Schierle GS, Kaminski CF. ERnet: a tool for the semantic segmentation and quantitative analysis of endoplasmic reticulum topology. Nat Methods 2023; 20:569-579. [PMID: 36997816 DOI: 10.1038/s41592-023-01815-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 02/10/2023] [Indexed: 04/01/2023]
Abstract
The ability to quantify structural changes of the endoplasmic reticulum (ER) is crucial for understanding the structure and function of this organelle. However, the rapid movement and complex topology of ER networks make this challenging. Here, we construct a state-of-the-art semantic segmentation method that we call ERnet for the automatic classification of sheet and tubular ER domains inside individual cells. Data are skeletonized and represented by connectivity graphs, enabling precise and efficient quantification of network connectivity. ERnet generates metrics on topology and integrity of ER structures and quantifies structural change in response to genetic or metabolic manipulation. We validate ERnet using data obtained by various ER-imaging methods from different cell types as well as ground truth images of synthetic ER structures. ERnet can be deployed in an automatic high-throughput and unbiased fashion and identifies subtle changes in ER phenotypes that may inform on disease progression and response to therapy.
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Affiliation(s)
- Meng Lu
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
- Cambridge Infinitus Research Centre, University of Cambridge, Cambridge, UK
| | - Charles N Christensen
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
- Artificial Intelligence Group, Department of Computer Science and Technology, University of Cambridge, Cambridge, UK
| | - Jana M Weber
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
- Delft Bioinformatics Lab, Intelligent Systems Department, Delft University of Technology, Delft, the Netherlands
| | - Tasuku Konno
- UK Dementia Research Institute at the University of Cambridge and Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Nino F Läubli
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Katharina M Scherer
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Edward Avezov
- UK Dementia Research Institute at the University of Cambridge and Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Pietro Lio
- Artificial Intelligence Group, Department of Computer Science and Technology, University of Cambridge, Cambridge, UK
| | - Alexei A Lapkin
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Gabriele S Kaminski Schierle
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
- Cambridge Infinitus Research Centre, University of Cambridge, Cambridge, UK
| | - Clemens F Kaminski
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK.
- Cambridge Infinitus Research Centre, University of Cambridge, Cambridge, UK.
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4
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Mukadam AS, Miller LVC, Smith AE, Vaysburd M, Sakya SA, Sanford S, Keeling S, Tuck BJ, Katsinelos T, Green C, Skov L, Kaalund SS, Foss S, Mayes K, O’Connell K, Wing M, Knox C, Banbury J, Avezov E, Rowe JB, Goedert M, Andersen JT, James LC, McEwan WA. Cytosolic antibody receptor TRIM21 is required for effective tau immunotherapy in mouse models. Science 2023; 379:1336-1341. [PMID: 36996217 PMCID: PMC7614512 DOI: 10.1126/science.abn1366] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 02/09/2023] [Indexed: 04/01/2023]
Abstract
Aggregates of the protein tau are proposed to drive pathogenesis in neurodegenerative diseases. Tau can be targeted by using passively transferred antibodies (Abs), but the mechanisms of Ab protection are incompletely understood. In this work, we used a variety of cell and animal model systems and showed that the cytosolic Ab receptor and E3 ligase TRIM21 (T21) could play a role in Ab protection against tau pathology. Tau-Ab complexes were internalized to the cytosol of neurons, which enabled T21 engagement and protection against seeded aggregation. Ab-mediated protection against tau pathology was lost in mice that lacked T21. Thus, the cytosolic compartment provides a site of immunotherapeutic protection, which may help in the design of Ab-based therapies in neurodegenerative disease.
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Affiliation(s)
- Aamir S Mukadam
- UK Dementia Research Institute at the University of Cambridge, Hills Road, Cambridge CB2 0AH, UK
- Department of Clinical Neurosciences, University of Cambridge, CB2 0AH
| | - Lauren VC Miller
- UK Dementia Research Institute at the University of Cambridge, Hills Road, Cambridge CB2 0AH, UK
- Department of Clinical Neurosciences, University of Cambridge, CB2 0AH
| | - Annabel E Smith
- UK Dementia Research Institute at the University of Cambridge, Hills Road, Cambridge CB2 0AH, UK
- Department of Clinical Neurosciences, University of Cambridge, CB2 0AH
| | - Marina Vaysburd
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Siri A Sakya
- Department of Immunology, University of Oslo and Oslo University Hospital Rikshospitalet, N-0424 Oslo, Norway
- Institute of Clinical Medicine and Department of Pharmacology, University of Oslo and Oslo University Hospital, N-0372 Oslo, Norway
| | - Sophie Sanford
- UK Dementia Research Institute at the University of Cambridge, Hills Road, Cambridge CB2 0AH, UK
- Department of Clinical Neurosciences, University of Cambridge, CB2 0AH
| | - Sophie Keeling
- UK Dementia Research Institute at the University of Cambridge, Hills Road, Cambridge CB2 0AH, UK
- Department of Clinical Neurosciences, University of Cambridge, CB2 0AH
| | - Benjamin J Tuck
- UK Dementia Research Institute at the University of Cambridge, Hills Road, Cambridge CB2 0AH, UK
- Department of Clinical Neurosciences, University of Cambridge, CB2 0AH
| | - Taxiarchis Katsinelos
- UK Dementia Research Institute at the University of Cambridge, Hills Road, Cambridge CB2 0AH, UK
- Department of Clinical Neurosciences, University of Cambridge, CB2 0AH
| | - Chris Green
- UK Dementia Research Institute at the University of Cambridge, Hills Road, Cambridge CB2 0AH, UK
- Department of Clinical Neurosciences, University of Cambridge, CB2 0AH
| | - Lise Skov
- UK Dementia Research Institute at the University of Cambridge, Hills Road, Cambridge CB2 0AH, UK
- Department of Clinical Neurosciences, University of Cambridge, CB2 0AH
| | - Sanne S Kaalund
- Department of Clinical Neurosciences, University of Cambridge, CB2 0AH
| | - Stian Foss
- Department of Immunology, University of Oslo and Oslo University Hospital Rikshospitalet, N-0424 Oslo, Norway
- Institute of Clinical Medicine and Department of Pharmacology, University of Oslo and Oslo University Hospital, N-0372 Oslo, Norway
| | - Keith Mayes
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Kevin O’Connell
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Mark Wing
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Claire Knox
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Jessica Banbury
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Edward Avezov
- UK Dementia Research Institute at the University of Cambridge, Hills Road, Cambridge CB2 0AH, UK
- Department of Clinical Neurosciences, University of Cambridge, CB2 0AH
| | - James B Rowe
- Department of Clinical Neurosciences, University of Cambridge, CB2 0AH
- Cambridge University Hospitals NHS Trust, Cambridge, CB2 0SZ
| | - Michel Goedert
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Jan Terje Andersen
- Department of Immunology, University of Oslo and Oslo University Hospital Rikshospitalet, N-0424 Oslo, Norway
- Institute of Clinical Medicine and Department of Pharmacology, University of Oslo and Oslo University Hospital, N-0372 Oslo, Norway
| | - Leo C James
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - William A McEwan
- UK Dementia Research Institute at the University of Cambridge, Hills Road, Cambridge CB2 0AH, UK
- Department of Clinical Neurosciences, University of Cambridge, CB2 0AH
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5
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Parutto P, Heck J, Lu M, Kaminski C, Avezov E, Heine M, Holcman D. High-throughput super-resolution single-particle trajectory analysis reconstructs organelle dynamics and membrane reorganization. Cell Rep Methods 2022; 2:100277. [PMID: 36046627 PMCID: PMC9421586 DOI: 10.1016/j.crmeth.2022.100277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 05/11/2022] [Accepted: 07/25/2022] [Indexed: 11/03/2022]
Abstract
Super-resolution imaging can generate thousands of single-particle trajectories. These data can potentially reconstruct subcellular organization and dynamics, as well as measure disease-linked changes. However, computational methods that can derive quantitative information from such massive datasets are currently lacking. We present data analysis and algorithms that are broadly applicable to reveal local binding and trafficking interactions and organization of dynamic subcellular sites. We applied this analysis to the endoplasmic reticulum and neuronal membrane. The method is based on spatiotemporal segmentation that explores data at multiple levels and detects the architecture and boundaries of high-density regions in areas measuring hundreds of nanometers. By connecting dense regions, we reconstructed the network topology of the endoplasmic reticulum (ER), as well as molecular flow redistribution and the local space explored by trajectories. The presented methods are available as an ImageJ plugin that can be applied to large datasets of overlapping trajectories offering a standard of single-particle trajectory (SPT) metrics.
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Affiliation(s)
- Pierre Parutto
- Group of Data Modeling and Computational Biology, IBENS, Ecole Normale Supérieure, 75005 Paris, France
| | - Jennifer Heck
- Research Group Functional Neurobiology at the Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Meng Lu
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Clemens Kaminski
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Edward Avezov
- UK Dementia Research Institute at the University of Cambridge and Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0AH, UK
| | - Martin Heine
- Research Group Functional Neurobiology at the Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - David Holcman
- Group of Data Modeling and Computational Biology, IBENS, Ecole Normale Supérieure, 75005 Paris, France
- DAMPT, University of Cambridge, DAMPT and Churchill College, Cambridge CB30DS, UK
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6
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Chung CW, Stephens AD, Konno T, Ward E, Avezov E, Kaminski CF, Hassanali AA, Kaminski Schierle GS. Intracellular Aβ42 Aggregation Leads to Cellular Thermogenesis. J Am Chem Soc 2022; 144:10034-10041. [PMID: 35616634 PMCID: PMC9185738 DOI: 10.1021/jacs.2c03599] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
The aggregation of
Aβ42 is a hallmark of Alzheimer’s
disease. It is still not known what the biochemical changes are inside
a cell which will eventually lead to Aβ42 aggregation. Thermogenesis
has been associated with cellular stress, the latter of which may
promote aggregation. We perform intracellular thermometry measurements
using fluorescent polymeric thermometers to show that Aβ42 aggregation
in live cells leads to an increase in cell-averaged temperatures.
This rise in temperature is mitigated upon treatment with an aggregation
inhibitor of Aβ42 and is independent of mitochondrial damage
that can otherwise lead to thermogenesis. With this, we present a
diagnostic assay which could be used to screen small-molecule inhibitors
to amyloid proteins in physiologically relevant settings. To interpret
our experimental observations and motivate the development of future
models, we perform classical molecular dynamics of model Aβ
peptides to examine the factors that hinder thermal dissipation. We
observe that this is controlled by the presence of ions in its surrounding
environment, the morphology of the amyloid peptides, and the extent
of its hydrogen-bonding interactions with water. We show that aggregation
and heat retention by Aβ peptides are favored under intracellular-mimicking
ionic conditions, which could potentially promote thermogenesis. The
latter will, in turn, trigger further nucleation events that accelerate
disease progression.
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Affiliation(s)
- Chyi Wei Chung
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, U.K
| | - Amberley D Stephens
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, U.K
| | - Tasuku Konno
- UK Dementia Research Institute, Department of Clinical Neuroscience, University of Cambridge, Cambridge CB2 0AH, U.K
| | - Edward Ward
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, U.K
| | - Edward Avezov
- UK Dementia Research Institute, Department of Clinical Neuroscience, University of Cambridge, Cambridge CB2 0AH, U.K
| | - Clemens F Kaminski
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, U.K
| | - Ali A Hassanali
- Condensed Matter and Statistical Physics, International Centre for Theoretical Physics, Strada Costiera 11, Trieste 34151, Italy
| | - Gabriele S Kaminski Schierle
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, U.K
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7
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Melo EP, Konno T, Farace I, Awadelkareem MA, Skov LR, Teodoro F, Sancho TP, Paton AW, Paton JC, Fares M, Paulo PMR, Zhang X, Avezov E. Stress-induced protein disaggregation in the endoplasmic reticulum catalysed by BiP. Nat Commun 2022; 13:2501. [PMID: 35523806 PMCID: PMC9076838 DOI: 10.1038/s41467-022-30238-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 04/20/2022] [Indexed: 01/31/2023] Open
Abstract
Protein synthesis is supported by cellular machineries that ensure polypeptides fold to their native conformation, whilst eliminating misfolded, aggregation prone species. Protein aggregation underlies pathologies including neurodegeneration. Aggregates’ formation is antagonised by molecular chaperones, with cytoplasmic machinery resolving insoluble protein aggregates. However, it is unknown whether an analogous disaggregation system exists in the Endoplasmic Reticulum (ER) where ~30% of the proteome is synthesised. Here we show that the ER of a variety of mammalian cell types, including neurons, is endowed with the capability to resolve protein aggregates under stress. Utilising a purpose-developed protein aggregation probing system with a sub-organellar resolution, we observe steady-state aggregate accumulation in the ER. Pharmacological induction of ER stress does not augment aggregates, but rather stimulate their clearance within hours. We show that this dissagregation activity is catalysed by the stress-responsive ER molecular chaperone – BiP. This work reveals a hitherto unknow, non-redundant strand of the proteostasis-restorative ER stress response. Aggregation of misfolded proteins underlie dementias. Here, the authors show that stressed cells activate an innate mechanism to resolve aggregates of defective proteins in the endoplasmic reticulum, where a third of cellular proteins are produced.
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Affiliation(s)
- Eduardo Pinho Melo
- Department of Clinical Neurosciences, UK Dementia Research Institute, University of Cambridge, Cambridge, UK. .,CCMAR-Centro de Ciências do Mar, Universidade do Algarve, Campus de Gambelas, Faro, Portugal.
| | - Tasuku Konno
- Department of Clinical Neurosciences, UK Dementia Research Institute, University of Cambridge, Cambridge, UK
| | - Ilaria Farace
- Department of Clinical Neurosciences, UK Dementia Research Institute, University of Cambridge, Cambridge, UK
| | - Mosab Ali Awadelkareem
- Department of Clinical Neurosciences, UK Dementia Research Institute, University of Cambridge, Cambridge, UK
| | - Lise R Skov
- Department of Clinical Neurosciences, UK Dementia Research Institute, University of Cambridge, Cambridge, UK
| | - Fernando Teodoro
- CCMAR-Centro de Ciências do Mar, Universidade do Algarve, Campus de Gambelas, Faro, Portugal
| | - Teresa P Sancho
- CCMAR-Centro de Ciências do Mar, Universidade do Algarve, Campus de Gambelas, Faro, Portugal
| | - Adrienne W Paton
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA, Australia
| | - James C Paton
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA, Australia
| | - Matthew Fares
- Department of Chemistry, The Pennsylvania State University, University Park, State College, PA, USA
| | - Pedro M R Paulo
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, Lisboa, Portugal
| | - Xin Zhang
- Department of Chemistry, The Pennsylvania State University, University Park, State College, PA, USA
| | - Edward Avezov
- Department of Clinical Neurosciences, UK Dementia Research Institute, University of Cambridge, Cambridge, UK.
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8
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Chambers JE, Zubkov N, Kubánková M, Nixon-Abell J, Mela I, Abreu S, Schwiening M, Lavarda G, López-Duarte I, Dickens JA, Torres T, Kaminski CF, Holt LJ, Avezov E, Huntington JA, George-Hyslop PS, Kuimova MK, Marciniak SJ. Z-α 1-antitrypsin polymers impose molecular filtration in the endoplasmic reticulum after undergoing phase transition to a solid state. Sci Adv 2022; 8:eabm2094. [PMID: 35394846 PMCID: PMC8993113 DOI: 10.1126/sciadv.abm2094] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 02/16/2022] [Indexed: 05/06/2023]
Abstract
Misfolding of secretory proteins in the endoplasmic reticulum (ER) features in many human diseases. In α1-antitrypsin deficiency, the pathogenic Z variant aberrantly assembles into polymers in the hepatocyte ER, leading to cirrhosis. We show that α1-antitrypsin polymers undergo a liquid:solid phase transition, forming a protein matrix that retards mobility of ER proteins by size-dependent molecular filtration. The Z-α1-antitrypsin phase transition is promoted during ER stress by an ATF6-mediated unfolded protein response. Furthermore, the ER chaperone calreticulin promotes Z-α1-antitrypsin solidification and increases protein matrix stiffness. Single-particle tracking reveals that solidification initiates in cells with normal ER morphology, previously assumed to represent a healthy pool. We show that Z-α1-antitrypsin-induced hypersensitivity to ER stress can be explained by immobilization of ER chaperones within the polymer matrix. This previously unidentified mechanism of ER dysfunction provides a template for understanding a diverse group of related proteinopathies and identifies ER chaperones as potential therapeutic targets.
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Affiliation(s)
- Joseph E. Chambers
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Nikita Zubkov
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Markéta Kubánková
- Department of Chemistry, Imperial College London, Wood Lane, London W12 0BZ, UK
| | - Jonathon Nixon-Abell
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Ioanna Mela
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, UK
| | - Susana Abreu
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Max Schwiening
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Giulia Lavarda
- Departamento de Química Orgánica and Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Ismael López-Duarte
- Departamento de Química Orgánica and Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Jennifer A. Dickens
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Tomás Torres
- Departamento de Química Orgánica and Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, Madrid 28049, Spain
- IMDEA Nanociencia, Campus de Cantoblanco, Madrid 28049, Spain
| | - Clemens F. Kaminski
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, UK
| | - Liam J. Holt
- Institute for Systems Genetics, New York University Grossman School of Medicine, 435 E 30th St, New York, NY 10016, USA
| | - Edward Avezov
- Department of Clinical Neurosciences and UK Dementia Research Institute, University of Cambridge, Cambridge CB2 0AH, UK
| | - James A. Huntington
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Peter St George-Hyslop
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
- Department of Medicine (Neurology), Temerty Faculty of Medicine, University of Toronto, University Health Network, Toronto, ON M5T 0S8, Canada
- Taub Institute For Research on Alzheimer’s Disease and the Ageing Brain, Department of Neurology, Columbia University Irvine Medical Center, 630 West 1/68 Street, New York, NY 10032, USA
| | - Marina K. Kuimova
- Department of Chemistry, Imperial College London, Wood Lane, London W12 0BZ, UK
| | - Stefan J. Marciniak
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
- Royal Papworth Hospital, Cambridge CB2 0AY, UK
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9
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Blomme A, Peter C, Mui E, Rodriguez Blanco G, An N, Mason LM, Jamieson LE, McGregor GH, Lilla S, Ntala C, Patel R, Thiry M, Kung SHY, Leclercq M, Ford CA, Rushworth LK, McGarry DJ, Mason S, Repiscak P, Nixon C, Salji MJ, Markert E, MacKay GM, Kamphorst JJ, Graham D, Faulds K, Fazli L, Gleave ME, Avezov E, Edwards J, Yin H, Sumpton D, Blyth K, Close P, Murphy DJ, Zanivan S, Leung HY. THEM6-mediated reprogramming of lipid metabolism supports treatment resistance in prostate cancer. EMBO Mol Med 2022; 14:e14764. [PMID: 35014179 PMCID: PMC8899912 DOI: 10.15252/emmm.202114764] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 12/13/2021] [Accepted: 12/15/2021] [Indexed: 12/21/2022] Open
Abstract
Despite the clinical benefit of androgen-deprivation therapy (ADT), the majority of patients with advanced prostate cancer (PCa) ultimately develop lethal castration-resistant prostate cancer (CRPC). In this study, we identified thioesterase superfamily member 6 (THEM6) as a marker of ADT resistance in PCa. THEM6 deletion reduces in vivo tumour growth and restores castration sensitivity in orthograft models of CRPC. Mechanistically, we show that the ER membrane-associated protein THEM6 regulates intracellular levels of ether lipids and is essential to trigger the induction of the ER stress response (UPR). Consequently, THEM6 loss in CRPC cells significantly alters ER function, reducing de novo sterol biosynthesis and preventing lipid-mediated activation of ATF4. Finally, we demonstrate that high THEM6 expression is associated with poor survival and correlates with high levels of UPR activation in PCa patients. Altogether, our results highlight THEM6 as a novel driver of therapy resistance in PCa as well as a promising target for the treatment of CRPC.
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Affiliation(s)
| | | | - Ernest Mui
- Institute of Cancer SciencesUniversity of GlasgowGarscube EstateGlasgowUK
| | | | - Ning An
- Laboratory of Cancer SignalingGIGA‐InstituteUniversity of LiègeLiègeBelgium
| | | | - Lauren E Jamieson
- Centre for Molecular NanometrologyDepartment of Pure and Applied ChemistryTechnology and Innovation CentreUniversity of StrathclydeGlasgowUK
| | - Grace H McGregor
- CRUK Beatson InstituteGarscube EstateGlasgowUK
- Institute of Cancer SciencesUniversity of GlasgowGarscube EstateGlasgowUK
| | | | - Chara Ntala
- CRUK Beatson InstituteGarscube EstateGlasgowUK
- Institute of Cancer SciencesUniversity of GlasgowGarscube EstateGlasgowUK
| | | | - Marc Thiry
- GIGA‐NeurosciencesUnit of Cell and Tissue BiologyUniversity of LiègeLiègeBelgium
| | - Sonia H Y Kung
- Department of Urologic SciencesFaculty of MedicineUniversity of British ColumbiaVancouverBCCanada
- Vancouver Prostate CentreVancouverBCCanada
| | - Marine Leclercq
- Laboratory of Cancer SignalingGIGA‐InstituteUniversity of LiègeLiègeBelgium
| | | | - Linda K Rushworth
- CRUK Beatson InstituteGarscube EstateGlasgowUK
- Institute of Cancer SciencesUniversity of GlasgowGarscube EstateGlasgowUK
| | | | - Susan Mason
- CRUK Beatson InstituteGarscube EstateGlasgowUK
| | | | - Colin Nixon
- CRUK Beatson InstituteGarscube EstateGlasgowUK
| | - Mark J Salji
- Institute of Cancer SciencesUniversity of GlasgowGarscube EstateGlasgowUK
| | - Elke Markert
- Institute of Cancer SciencesUniversity of GlasgowGarscube EstateGlasgowUK
| | | | - Jurre J Kamphorst
- CRUK Beatson InstituteGarscube EstateGlasgowUK
- Institute of Cancer SciencesUniversity of GlasgowGarscube EstateGlasgowUK
| | - Duncan Graham
- Centre for Molecular NanometrologyDepartment of Pure and Applied ChemistryTechnology and Innovation CentreUniversity of StrathclydeGlasgowUK
| | - Karen Faulds
- Centre for Molecular NanometrologyDepartment of Pure and Applied ChemistryTechnology and Innovation CentreUniversity of StrathclydeGlasgowUK
| | - Ladan Fazli
- Department of Urologic SciencesFaculty of MedicineUniversity of British ColumbiaVancouverBCCanada
- Vancouver Prostate CentreVancouverBCCanada
| | - Martin E Gleave
- Department of Urologic SciencesFaculty of MedicineUniversity of British ColumbiaVancouverBCCanada
- Vancouver Prostate CentreVancouverBCCanada
| | - Edward Avezov
- UK Dementia Research Institute at University of CambridgeDepartment of Clinical NeurosciencesUniversity of CambridgeCambridgeUK
| | - Joanne Edwards
- Institute of Cancer SciencesUniversity of GlasgowGarscube EstateGlasgowUK
| | - Huabing Yin
- School of EngineeringUniversity of GlasgowGlasgowUK
| | | | - Karen Blyth
- CRUK Beatson InstituteGarscube EstateGlasgowUK
- Institute of Cancer SciencesUniversity of GlasgowGarscube EstateGlasgowUK
| | - Pierre Close
- Laboratory of Cancer SignalingGIGA‐InstituteUniversity of LiègeLiègeBelgium
| | - Daniel J Murphy
- CRUK Beatson InstituteGarscube EstateGlasgowUK
- Institute of Cancer SciencesUniversity of GlasgowGarscube EstateGlasgowUK
| | - Sara Zanivan
- CRUK Beatson InstituteGarscube EstateGlasgowUK
- Institute of Cancer SciencesUniversity of GlasgowGarscube EstateGlasgowUK
| | - Hing Y Leung
- CRUK Beatson InstituteGarscube EstateGlasgowUK
- Institute of Cancer SciencesUniversity of GlasgowGarscube EstateGlasgowUK
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10
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Konno T, Melo EP, Chambers JE, Avezov E. Intracellular Sources of ROS/H 2O 2 in Health and Neurodegeneration: Spotlight on Endoplasmic Reticulum. Cells 2021; 10:233. [PMID: 33504070 PMCID: PMC7912550 DOI: 10.3390/cells10020233] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 01/15/2021] [Accepted: 01/18/2021] [Indexed: 02/08/2023] Open
Abstract
Reactive oxygen species (ROS) are produced continuously throughout the cell as products of various redox reactions. Yet these products function as important signal messengers, acting through oxidation of specific target factors. Whilst excess ROS production has the potential to induce oxidative stress, physiological roles of ROS are supported by a spatiotemporal equilibrium between ROS producers and scavengers such as antioxidative enzymes. In the endoplasmic reticulum (ER), hydrogen peroxide (H2O2), a non-radical ROS, is produced through the process of oxidative folding. Utilisation and dysregulation of H2O2, in particular that generated in the ER, affects not only cellular homeostasis but also the longevity of organisms. ROS dysregulation has been implicated in various pathologies including dementia and other neurodegenerative diseases, sanctioning a field of research that strives to better understand cell-intrinsic ROS production. Here we review the organelle-specific ROS-generating and consuming pathways, providing evidence that the ER is a major contributing source of potentially pathologic ROS.
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Affiliation(s)
- Tasuku Konno
- Department of Clinical Neurosciences, UK Dementia Research Institute, University of Cambridge, Cambridge CB2 0AH, UK
| | - Eduardo Pinho Melo
- CCMAR—Centro de Ciências do Mar, Campus de Gambelas, Universidade do Algarve, 8005-139 Faro, Portugal;
| | - Joseph E. Chambers
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK;
| | - Edward Avezov
- Department of Clinical Neurosciences, UK Dementia Research Institute, University of Cambridge, Cambridge CB2 0AH, UK
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11
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Lu M, van Tartwijk FW, Lin JQ, Nijenhuis W, Parutto P, Fantham M, Christensen CN, Avezov E, Holt CE, Tunnacliffe A, Holcman D, Kapitein L, Schierle GSK, Kaminski CF. The structure and global distribution of the endoplasmic reticulum network are actively regulated by lysosomes. Sci Adv 2020; 6:eabc7209. [PMID: 33328230 PMCID: PMC7744115 DOI: 10.1126/sciadv.abc7209] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Accepted: 10/27/2020] [Indexed: 06/12/2023]
Abstract
The endoplasmic reticulum (ER) comprises morphologically and functionally distinct domains: sheets and interconnected tubules. These domains undergo dynamic reshaping in response to changes in the cellular environment. However, the mechanisms behind this rapid remodeling are largely unknown. Here, we report that ER remodeling is actively driven by lysosomes, following lysosome repositioning in response to changes in nutritional status: The anchorage of lysosomes to ER growth tips is critical for ER tubule elongation and connection. We validate this causal link via the chemo- and optogenetically driven repositioning of lysosomes, which leads to both a redistribution of the ER tubules and a change of its global morphology. Therefore, lysosomes sense metabolic change in the cell and regulate ER tubule distribution accordingly. Dysfunction in this mechanism during axonal extension may lead to axonal growth defects. Our results demonstrate a critical role of lysosome-regulated ER dynamics and reshaping in nutrient responses and neuronal development.
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Affiliation(s)
- Meng Lu
- Cambridge Infinitus Research Centre, Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Francesca W van Tartwijk
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Julie Qiaojin Lin
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
- UK Dementia Research Institute at the University of Cambridge and Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0AH, UK
| | - Wilco Nijenhuis
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, Netherlands
| | - Pierre Parutto
- Group of Computational Biology and Applied Mathematics, Institut de Biologie de l'École Normale Supérieure-PSL, 46 rue d'Ulm, 75005 Paris, France
| | - Marcus Fantham
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Charles N Christensen
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Edward Avezov
- UK Dementia Research Institute at the University of Cambridge and Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0AH, UK
| | - Christine E Holt
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK
| | - Alan Tunnacliffe
- Cambridge Infinitus Research Centre, Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - David Holcman
- Group of Computational Biology and Applied Mathematics, Institut de Biologie de l'École Normale Supérieure-PSL, 46 rue d'Ulm, 75005 Paris, France
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB3 0WA, UK
| | - Lukas Kapitein
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, Netherlands
| | - Gabriele S Kaminski Schierle
- Cambridge Infinitus Research Centre, Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Clemens F Kaminski
- Cambridge Infinitus Research Centre, Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK.
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
- UK Dementia Research Institute at the University of Cambridge and Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0AH, UK
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12
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Parutto P, Chambers JE, Fantham M, Young L, Marciniak S, Kaminski CF, Ron D, Holcman D, Avezov E. Single Particle Trajectories Reveal Active Endoplasmic Reticulum Luminal Flow. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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13
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Chambers JE, Kubánková M, Huber RG, López-Duarte I, Avezov E, Bond PJ, Marciniak SJ, Kuimova MK. An Optical Technique for Mapping Microviscosity Dynamics in Cellular Organelles. ACS Nano 2018; 12:4398-4407. [PMID: 29648785 DOI: 10.1021/acsnano.8b00177] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Microscopic viscosity (microviscosity) is a key determinant of diffusion in the cell and defines the rate of biological processes occurring at the nanoscale, including enzyme-driven metabolism and protein folding. Here we establish a rotor-based organelle viscosity imaging (ROVI) methodology that enables real-time quantitative mapping of cell microviscosity. This approach uses environment-sensitive dyes termed molecular rotors, covalently linked to genetically encoded probes to provide compartment-specific microviscosity measurements via fluorescence lifetime imaging. ROVI visualized spatial and temporal dynamics of microviscosity with suborganellar resolution, reporting on a microviscosity difference of nearly an order of magnitude between subcellular compartments. In the mitochondrial matrix, ROVI revealed several striking findings: a broad heterogeneity of microviscosity among individual mitochondria, unparalleled resilience to osmotic stress, and real-time changes in microviscosity during mitochondrial depolarization. These findings demonstrate the use of ROVI to explore the biophysical mechanisms underlying cell biological processes.
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Affiliation(s)
- Joseph E Chambers
- Cambridge Institute for Medical Research (CIMR), Department of Medicine , University of Cambridge , Wellcome Trust/MRC Building, Hills Road , Cambridge , CB2 0XY , United Kingdom
| | - Markéta Kubánková
- Department of Chemistry , Imperial College London , South Kensington , London , SW7 2AZ , United Kingdom
| | - Roland G Huber
- Bioinformatics Institute (BII) , Agency for Science, Technology, and Research (A*STAR) , Matrix 07-01, 30 Biopolis Street , 138671 Singapore
| | - Ismael López-Duarte
- Department of Chemistry , Imperial College London , South Kensington , London , SW7 2AZ , United Kingdom
| | - Edward Avezov
- UK Dementia Research Institute at the University of Cambridge , Cambridge Biomedical Campus, Cambridge CB2 0AH , United Kingdom
| | - Peter J Bond
- Bioinformatics Institute (BII) , Agency for Science, Technology, and Research (A*STAR) , Matrix 07-01, 30 Biopolis Street , 138671 Singapore
- Department of Biological Sciences , National University of Singapore , 14 Science Drive 4 , 117543 Singapore
| | - Stefan J Marciniak
- Cambridge Institute for Medical Research (CIMR), Department of Medicine , University of Cambridge , Wellcome Trust/MRC Building, Hills Road , Cambridge , CB2 0XY , United Kingdom
| | - Marina K Kuimova
- Department of Chemistry , Imperial College London , South Kensington , London , SW7 2AZ , United Kingdom
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14
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Mehmeti I, Lortz S, Avezov E, Jörns A, Lenzen S. ER-resident antioxidative GPx7 and GPx8 enzyme isoforms protect insulin-secreting INS-1E β-cells against lipotoxicity by improving the ER antioxidative capacity. Free Radic Biol Med 2017; 112:121-130. [PMID: 28751022 DOI: 10.1016/j.freeradbiomed.2017.07.021] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 07/20/2017] [Accepted: 07/22/2017] [Indexed: 12/16/2022]
Abstract
Increased circulating levels of saturated fatty acids (FFAs) and glucose are considered to be major mediators of β-cell dysfunction and death in T2DM. Although it has been proposed that endoplasmic reticulum (ER) and oxidative stress play a crucial role in gluco/lipotoxicity, their interplay and relative contribution to β-cell dysfunction and apoptosis has not been fully elucidated. In addition it is still unclear how palmitate - the physiologically most abundant long-chain saturated FFA - elicits ER stress and which immediate signals commit β-cells to apoptosis. To study the underlying mechanisms of palmitate-mediated ER stress and β-cell toxicity, we exploited the observation that the recently described ER-resident GPx7 and GPx8 are not expressed in rat β-cells. Expression of GPx7 or GPx8 attenuated FFAs-mediated H2O2 generation, ER stress, and apoptosis induction. These results could be confirmed by a H2O2-specific inactivating ER catalase, indicating that accumulation of H2O2 in the ER lumen is critical in FFA-induced ER stress. Furthermore, neither the expression of GPx7 nor of GPx8 increased insulin content or facilitated disulfide bond formation in insulin-secreting INS-1E cells. Hence, reduction of H2O2 by ER-GPx isoforms is not rate-limiting in oxidative protein folding in rat β-cells. These data suggest that FFA-mediated ER stress is partially dependent on oxidative stress and selective expression of GPx7 or GPx8 improves the ER antioxidative capacity of rat β-cells without compromising insulin production and the oxidative protein folding machinery.
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Affiliation(s)
- Ilir Mehmeti
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany.
| | - Stephan Lortz
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany
| | - Edward Avezov
- University of Cambridge, Cambridge Institute for Medical Research, the Wellcome Trust MRC Institute of Metabolic Science and NIHR Cambridge Biomedical Research Centre, Cambridge CB2 0XY, United Kingdom
| | - Anne Jörns
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany
| | - Sigurd Lenzen
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany; Institute of Experimental Diabetes Research, Hannover Medical School, Hannover, Germany.
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15
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Kollmann K, Warsch W, Gonzalez-Arias C, Nice FL, Avezov E, Milburn J, Li J, Dimitropoulou D, Biddie S, Wang M, Poynton E, Colzani M, Tijssen MR, Anand S, McDermott U, Huntly B, Green T. A novel signalling screen demonstrates that CALR mutations activate essential MAPK signalling and facilitate megakaryocyte differentiation. Leukemia 2017; 31:934-944. [PMID: 27740635 PMCID: PMC5383931 DOI: 10.1038/leu.2016.280] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 08/18/2016] [Accepted: 08/24/2016] [Indexed: 12/15/2022]
Abstract
Most myeloproliferative neoplasm (MPN) patients lacking JAK2 mutations harbour somatic CALR mutations that are thought to activate cytokine signalling although the mechanism is unclear. To identify kinases important for survival of CALR-mutant cells, we developed a novel strategy (KISMET) that utilizes the full range of kinase selectivity data available from each inhibitor and thus takes advantage of off-target noise that limits conventional small-interfering RNA or inhibitor screens. KISMET successfully identified known essential kinases in haematopoietic and non-haematopoietic cell lines and identified the mitogen activated protein kinase (MAPK) pathway as required for growth of the CALR-mutated MARIMO cells. Expression of mutant CALR in murine or human haematopoietic cell lines was accompanied by myeloproliferative leukemia protein (MPL)-dependent activation of MAPK signalling, and MPN patients with CALR mutations showed increased MAPK activity in CD34 cells, platelets and megakaryocytes. Although CALR mutations resulted in protein instability and proteosomal degradation, mutant CALR was able to enhance megakaryopoiesis and pro-platelet production from human CD34+ progenitors. These data link aberrant MAPK activation to the MPN phenotype and identify it as a potential therapeutic target in CALR-mutant positive MPNs.
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Affiliation(s)
- K Kollmann
- Cambridge Institute for Medical Research and Wellcome Trust/MRC Stem Cell Institute, University of Cambridge, Cambridge, UK
- Department of Haematology, University of Cambridge, Cambridge, UK
| | - W Warsch
- Cambridge Institute for Medical Research and Wellcome Trust/MRC Stem Cell Institute, University of Cambridge, Cambridge, UK
- Department of Haematology, University of Cambridge, Cambridge, UK
| | - C Gonzalez-Arias
- Cambridge Institute for Medical Research and Wellcome Trust/MRC Stem Cell Institute, University of Cambridge, Cambridge, UK
- Department of Haematology, University of Cambridge, Cambridge, UK
| | - F L Nice
- Cambridge Institute for Medical Research and Wellcome Trust/MRC Stem Cell Institute, University of Cambridge, Cambridge, UK
- Department of Haematology, University of Cambridge, Cambridge, UK
| | - E Avezov
- Cambridge Institute for Medical Research, Wellcome Trust MRC Institute of Metabolic Science and NIHR Cambridge Biomedical Research Centre, Cambridge, UK
| | - J Milburn
- Cambridge Institute for Medical Research and Wellcome Trust/MRC Stem Cell Institute, University of Cambridge, Cambridge, UK
- Department of Haematology, University of Cambridge, Cambridge, UK
| | - J Li
- Cambridge Institute for Medical Research and Wellcome Trust/MRC Stem Cell Institute, University of Cambridge, Cambridge, UK
- Department of Haematology, University of Cambridge, Cambridge, UK
| | - D Dimitropoulou
- Cambridge Institute for Medical Research and Wellcome Trust/MRC Stem Cell Institute, University of Cambridge, Cambridge, UK
- Department of Haematology, University of Cambridge, Cambridge, UK
| | - S Biddie
- Cambridge Institute for Medical Research and Wellcome Trust/MRC Stem Cell Institute, University of Cambridge, Cambridge, UK
- Department of Haematology, University of Cambridge, Cambridge, UK
| | - M Wang
- Cambridge Institute for Medical Research and Wellcome Trust/MRC Stem Cell Institute, University of Cambridge, Cambridge, UK
- Department of Haematology, University of Cambridge, Cambridge, UK
| | - E Poynton
- Cambridge Institute for Medical Research and Wellcome Trust/MRC Stem Cell Institute, University of Cambridge, Cambridge, UK
- Department of Haematology, University of Cambridge, Cambridge, UK
| | - M Colzani
- Department of Haematology, University of Cambridge, and National Health Service Blood and Transplant, Cambridge Biomedical Campus, Cambridge, UK
| | - M R Tijssen
- Department of Haematology, University of Cambridge, and National Health Service Blood and Transplant, Cambridge Biomedical Campus, Cambridge, UK
| | - S Anand
- Cambridge Institute for Medical Research and Wellcome Trust/MRC Stem Cell Institute, University of Cambridge, Cambridge, UK
- Department of Haematology, University of Cambridge, Cambridge, UK
| | - U McDermott
- Cancer Genome Project, Wellcome Trust Sanger Institute, Genome Campus, Hinxton, Cambridgeshire, UK
| | - B Huntly
- Cambridge Institute for Medical Research and Wellcome Trust/MRC Stem Cell Institute, University of Cambridge, Cambridge, UK
- Department of Haematology, University of Cambridge, Cambridge, UK
- Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - T Green
- Cambridge Institute for Medical Research and Wellcome Trust/MRC Stem Cell Institute, University of Cambridge, Cambridge, UK
- Department of Haematology, University of Cambridge, Cambridge, UK
- Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
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16
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Melo EP, Lopes C, Gollwitzer P, Lortz S, Lenzen S, Mehmeti I, Kaminski CF, Ron D, Avezov E. TriPer, an optical probe tuned to the endoplasmic reticulum tracks changes in luminal H 2O 2. BMC Biol 2017; 15:24. [PMID: 28347335 PMCID: PMC5368998 DOI: 10.1186/s12915-017-0367-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 03/14/2017] [Indexed: 11/27/2022] Open
Abstract
Background The fate of hydrogen peroxide (H2O2) in the endoplasmic reticulum (ER) has been inferred indirectly from the activity of ER-localized thiol oxidases and peroxiredoxins, in vitro, and the consequences of their genetic manipulation, in vivo. Over the years hints have suggested that glutathione, puzzlingly abundant in the ER lumen, might have a role in reducing the heavy burden of H2O2 produced by the luminal enzymatic machinery for disulfide bond formation. However, limitations in existing organelle-targeted H2O2 probes have rendered them inert in the thiol-oxidizing ER, precluding experimental follow-up of glutathione’s role in ER H2O2 metabolism. Results Here we report on the development of TriPer, a vital optical probe sensitive to changes in the concentration of H2O2 in the thiol-oxidizing environment of the ER. Consistent with the hypothesized contribution of oxidative protein folding to H2O2 production, ER-localized TriPer detected an increase in the luminal H2O2 signal upon induction of pro-insulin (a disulfide-bonded protein of pancreatic β-cells), which was attenuated by the ectopic expression of catalase in the ER lumen. Interfering with glutathione production in the cytosol by buthionine sulfoximine (BSO) or enhancing its localized destruction by expression of the glutathione-degrading enzyme ChaC1 in the lumen of the ER further enhanced the luminal H2O2 signal and eroded β-cell viability. Conclusions A tri-cysteine system with a single peroxidatic thiol enables H2O2 detection in oxidizing milieux such as that of the ER. Tracking ER H2O2 in live pancreatic β-cells points to a role for glutathione in H2O2 turnover. Electronic supplementary material The online version of this article (doi:10.1186/s12915-017-0367-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Eduardo Pinho Melo
- University of Cambridge, Cambridge Institute for Medical Research, the Wellcome Trust MRC Institute of Metabolic Science and NIHR Cambridge Biomedical Research Centre, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK.,Centre for Biomedical Research, Universidade do Algarve, Faro, Portugal
| | - Carlos Lopes
- Centre for Biomedical Research, Universidade do Algarve, Faro, Portugal
| | - Peter Gollwitzer
- University of Cambridge, Cambridge Institute for Medical Research, the Wellcome Trust MRC Institute of Metabolic Science and NIHR Cambridge Biomedical Research Centre, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK
| | - Stephan Lortz
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, 30625, Germany
| | - Sigurd Lenzen
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, 30625, Germany
| | - Ilir Mehmeti
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, 30625, Germany
| | - Clemens F Kaminski
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB2 3RA, UK
| | - David Ron
- University of Cambridge, Cambridge Institute for Medical Research, the Wellcome Trust MRC Institute of Metabolic Science and NIHR Cambridge Biomedical Research Centre, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK.
| | - Edward Avezov
- University of Cambridge, Cambridge Institute for Medical Research, the Wellcome Trust MRC Institute of Metabolic Science and NIHR Cambridge Biomedical Research Centre, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK.
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17
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Blacker T, Chen W, Avezov E, Marsh RJ, Duchen MR, Kaminski CF, Bain AJ. Investigating State Restriction in Fluorescent Protein FRET Using Time-Resolved Fluorescence and Anisotropy. J Phys Chem C Nanomater Interfaces 2017; 121:1507-1514. [PMID: 28217242 PMCID: PMC5309863 DOI: 10.1021/acs.jpcc.6b11235] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 12/23/2016] [Indexed: 05/14/2023]
Abstract
Most fluorescent proteins exhibit multiexponential fluorescence decays, indicating a heterogeneous excited state population. FRET between fluorescent proteins should therefore involve multiple energy transfer pathways. We recently demonstrated the FRET pathways between EGFP and mCherry (mC), upon the dimerization of 3-phosphoinositide dependent protein kinase 1 (PDK1), to be highly restricted. A mechanism for FRET restriction based on a highly unfavorable κ2 orientation factor arising from differences in donor-acceptor transition dipole moment angles in a far from coplanar and near static interaction geometry was proposed. Here this is tested via FRET to mC arising from the association of glutathione (GSH) and glutathione S-transferase (GST) with an intrinsically homogeneous and more mobile donor Oregon Green 488 (OG). A new analysis of the acceptor window intensity, based on the turnover point of the sensitized fluorescence, is combined with donor window intensity and anisotropy measurements which show that unrestricted FRET to mC takes place. However, a long-lived anisotropy decay component in the donor window reveals a GST-GSH population in which FRET does not occur, explaining previous discrepancies between quantitative FRET measurements of GST-GSH association and their accepted values. This reinforces the importance of the local donor-acceptor environment in mediating energy transfer and the need to perform spectrally resolved intensity and anisotropy decay measurements in the accurate quantification of fluorescent protein FRET.
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Affiliation(s)
- Thomas
S. Blacker
- Department
of Physics & Astronomy, Centre for Mathematics and Physics
in the Life Sciences and Experimental Biology, and Department of Cell & Developmental
Biology, University College London, Gower Street, London WC1E 6BT, United
Kingdom
| | - WeiYue Chen
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, United Kingdom
| | - Edward Avezov
- Cambridge
Institute for Medical Research, University
of Cambridge, Cambridge CB2 0XY, United Kingdom
| | - Richard J. Marsh
- Department
of Physics & Astronomy, Centre for Mathematics and Physics
in the Life Sciences and Experimental Biology, and Department of Cell & Developmental
Biology, University College London, Gower Street, London WC1E 6BT, United
Kingdom
| | - Michael R. Duchen
- Department
of Physics & Astronomy, Centre for Mathematics and Physics
in the Life Sciences and Experimental Biology, and Department of Cell & Developmental
Biology, University College London, Gower Street, London WC1E 6BT, United
Kingdom
| | - Clemens F. Kaminski
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, United Kingdom
| | - Angus J. Bain
- Department
of Physics & Astronomy, Centre for Mathematics and Physics
in the Life Sciences and Experimental Biology, and Department of Cell & Developmental
Biology, University College London, Gower Street, London WC1E 6BT, United
Kingdom
- E-mail:
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18
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Konno T, Pinho Melo E, Lopes C, Mehmeti I, Lenzen S, Ron D, Avezov E. ERO1-independent production of H2O2 within the endoplasmic reticulum fuels Prdx4-mediated oxidative protein folding. J Cell Biol 2016; 211:253-9. [PMID: 26504166 PMCID: PMC4621842 DOI: 10.1083/jcb.201506123] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Tracking the kinetics of equilibration of H2O2 between compartments reveals unexpected isolation of the endoplasmic reticulum and hints at a hitherto unsuspected local source of peroxide. The endoplasmic reticulum (ER)–localized peroxiredoxin 4 (PRDX4) supports disulfide bond formation in eukaryotic cells lacking endoplasmic reticulum oxidase 1 (ERO1). The source of peroxide that fuels PRDX4-mediated disulfide bond formation has remained a mystery, because ERO1 is believed to be a major producer of hydrogen peroxide (H2O2) in the ER lumen. We report on a simple kinetic technique to track H2O2 equilibration between cellular compartments, suggesting that the ER is relatively isolated from cytosolic or mitochondrial H2O2 pools. Furthermore, expression of an ER-adapted catalase to degrade lumenal H2O2 attenuated PRDX4-mediated disulfide bond formation in cells lacking ERO1, whereas depletion of H2O2 in the cytosol or mitochondria had no similar effect. ER catalase did not effect the slow residual disulfide bond formation in cells lacking both ERO1 and PRDX4. These observations point to exploitation of a hitherto unrecognized lumenal source of H2O2 by PRDX4 and a parallel slow H2O2-independent pathway for disulfide formation.
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Affiliation(s)
- Tasuku Konno
- University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust Medical Research Council Institute of Metabolic Science and National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, CB2 0XY, UK
| | - Eduardo Pinho Melo
- Center for Biomedical Research, Universidade do Algarve, Faro, Portugal 8005-139
| | - Carlos Lopes
- Center for Biomedical Research, Universidade do Algarve, Faro, Portugal 8005-139
| | - Ilir Mehmeti
- Institute of Clinical Biochemistry, Hannover Medical School, 30625 Hannover, Germany
| | - Sigurd Lenzen
- Institute of Clinical Biochemistry, Hannover Medical School, 30625 Hannover, Germany
| | - David Ron
- University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust Medical Research Council Institute of Metabolic Science and National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, CB2 0XY, UK
| | - Edward Avezov
- University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust Medical Research Council Institute of Metabolic Science and National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, CB2 0XY, UK
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19
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Chen W, Avezov E, Schlachter SC, Gielen F, Laine RF, Harding HP, Hollfelder F, Ron D, Kaminski CF. A method to quantify FRET stoichiometry with phasor plot analysis and acceptor lifetime ingrowth. Biophys J 2016; 108:999-1002. [PMID: 25762312 PMCID: PMC4375440 DOI: 10.1016/j.bpj.2015.01.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 11/23/2014] [Accepted: 01/09/2015] [Indexed: 11/26/2022] Open
Abstract
FRET is widely used for the study of protein-protein interactions in biological samples. However, it is difficult to quantify both the FRET efficiency (E) and the affinity (Kd) of the molecular interaction from intermolecular FRET signals in samples of unknown stoichiometry. Here, we present a method for the simultaneous quantification of the complete set of interaction parameters, including fractions of bound donors and acceptors, local protein concentrations, and dissociation constants, in each image pixel. The method makes use of fluorescence lifetime information from both donor and acceptor molecules and takes advantage of the linear properties of the phasor plot approach. We demonstrate the capability of our method in vitro in a microfluidic device and also in cells, via the determination of the binding affinity between tagged versions of glutathione and glutathione S-transferase, and via the determination of competitor concentration. The potential of the method is explored with simulations.
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Affiliation(s)
- WeiYue Chen
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, United Kingdom
| | - Edward Avezov
- The Wellcome Trust Medical Research Council Institute of Metabolic Science and National Institute for Health Research, Cambridge Biomedical Research Centre, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Simon C Schlachter
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, United Kingdom
| | - Fabrice Gielen
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Romain F Laine
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, United Kingdom
| | - Heather P Harding
- The Wellcome Trust Medical Research Council Institute of Metabolic Science and National Institute for Health Research, Cambridge Biomedical Research Centre, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Florian Hollfelder
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - David Ron
- The Wellcome Trust Medical Research Council Institute of Metabolic Science and National Institute for Health Research, Cambridge Biomedical Research Centre, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Clemens F Kaminski
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, United Kingdom.
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20
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Preissler S, Chambers JE, Crespillo-Casado A, Avezov E, Miranda E, Perez J, Hendershot LM, Harding HP, Ron D. Physiological modulation of BiP activity by trans-protomer engagement of the interdomain linker. eLife 2015; 4:e08961. [PMID: 26473973 PMCID: PMC4608358 DOI: 10.7554/elife.08961] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2015] [Accepted: 09/16/2015] [Indexed: 12/19/2022] Open
Abstract
DnaK/Hsp70 chaperones form oligomers of poorly understood structure and functional significance. Site-specific proteolysis and crosslinking were used to probe the architecture of oligomers formed by the endoplasmic reticulum (ER) Hsp70, BiP. These were found to consist of adjacent protomers engaging the interdomain linker of one molecule in the substrate binding site of another, attenuating the chaperone function of oligomeric BiP. Native gel electrophoresis revealed a rapidly-modulated reciprocal relationship between the burden of unfolded proteins and BiP oligomers and slower equilibration between oligomers and inactive, covalently-modified BiP. Lumenal ER calcium depletion caused rapid oligomerization of mammalian BiP and a coincidental diminution in substrate binding, pointing to the relative inertness of the oligomers. Thus, equilibration between inactive oligomers and active monomeric BiP is poised to buffer fluctuations in ER unfolded protein load on a rapid timescale attainable neither by inter-conversion of active and covalently-modified BiP nor by the conventional unfolded protein response. DOI:http://dx.doi.org/10.7554/eLife.08961.001 Proteins are composed of long chains of amino acids that fold on themselves to form three-dimensional structures. Many proteins are made in a compartment within the cell called the endoplasmic reticulum and ‘chaperone’ proteins help them fold correctly. Cells carefully regulate the levels of chaperone proteins. If there are too few chaperones in the cell, then newly-made proteins may fold incorrectly and interrupt other processes. On the other hand, if too many chaperones are present they may slow down the protein folding process. If a cell experiences stressful conditions, or if there is a sudden demand for more proteins to be made, protein folding can be disrupted. This leads to an increase in the number of unfolded proteins in the endoplasmic reticulum and so the cell increases the levels of chaperone proteins to cope with this. Hsp70 chaperones are one family of chaperone proteins. These proteins can be present in a cell as single molecules (monomers) or as a group of several chaperone molecules (oligomers). Previous research has suggested that the chaperone proteins in oligomers are inactive, but the oligomers may be rapidly broken down into monomers when the cell needs to fold more proteins. A region within the Hsp70 called the ‘interdomain linker’ is important for regulating the chaperone activity, but it is not clear if this is connected to the formation of oligomers. Preissler et al. used biochemical techniques to study how an Hsp70 protein in the endoplasmic reticulum called BiP forms oligomers. The experiments show that oligomers form when the interdomain linker of one BiP molecule is bound to the region of an adjacent BiP molecule that is normally reserved for binding to unfolded proteins. The presence of the interdomain linker makes it more difficult for unfolded proteins to bind. Further experiments challenged cells with chemicals that caused the number of unfolded proteins in the cells to increase. Under these conditions, there was a decrease in the number of BiP molecules associated with oligomers. Preissler et al. propose that BiP oligomers act as reservoirs to store BiP molecules when they aren't needed by the cell. However, when the levels of unfolded proteins rise, cells can rapidly break up these oligomers to make active monomers that help to deal with the excess numbers of unfolded proteins. Further work is needed to understand how changes in the number of unfolded proteins in cells leads to the formation and disassembly of BiP oligomers. DOI:http://dx.doi.org/10.7554/eLife.08961.002
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Affiliation(s)
- Steffen Preissler
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Joseph E Chambers
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Ana Crespillo-Casado
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Edward Avezov
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Elena Miranda
- Department of Biology and Biotechnology, Charles Darwin, Sapienza University of Rome, Rome, Italy
| | - Juan Perez
- Laboratorio de Fisiología, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain
| | - Linda M Hendershot
- Department of Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, United States
| | - Heather P Harding
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - David Ron
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom.,Wellcome Trust-MRC Institute of Metabolic Science, NIHR Cambridge Biomedical Research Centre, University of Cambridge, Cambridge, United Kingdom
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21
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Avezov E, Konno T, Zyryanova A, Chen W, Laine R, Crespillo-Casado A, Melo EP, Ushioda R, Nagata K, Kaminski CF, Harding HP, Ron D. Retarded PDI diffusion and a reductive shift in poise of the calcium depleted endoplasmic reticulum. BMC Biol 2015; 13:2. [PMID: 25575667 PMCID: PMC4316587 DOI: 10.1186/s12915-014-0112-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 12/23/2014] [Indexed: 11/26/2022] Open
Abstract
Background Endoplasmic reticulum (ER) lumenal protein thiol redox balance resists dramatic variation in unfolded protein load imposed by diverse physiological challenges including compromise in the key upstream oxidases. Lumenal calcium depletion, incurred during normal cell signaling, stands out as a notable exception to this resilience, promoting a rapid and reversible shift towards a more reducing poise. Calcium depletion induced ER redox alterations are relevant to physiological conditions associated with calcium signaling, such as the response of pancreatic cells to secretagogues and neuronal activity. The core components of the ER redox machinery are well characterized; however, the molecular basis for the calcium-depletion induced shift in redox balance is presently obscure. Results In vitro, the core machinery for generating disulfides, consisting of ERO1 and the oxidizing protein disulfide isomerase, PDI1A, was indifferent to variation in calcium concentration within the physiological range. However, ER calcium depletion in vivo led to a selective 2.5-fold decline in PDI1A mobility, whereas the mobility of the reducing PDI family member, ERdj5 was unaffected. In vivo, fluorescence resonance energy transfer measurements revealed that declining PDI1A mobility correlated with formation of a complex with the abundant ER chaperone calreticulin, whose mobility was also inhibited by calcium depletion and the calcium depletion-mediated reductive shift was attenuated in cells lacking calreticulin. Measurements with purified proteins confirmed that the PDI1A-calreticulin complex dissociated as Ca2+ concentrations approached those normally found in the ER lumen ([Ca2+]K0.5max = 190 μM). Conclusions Our findings suggest that selective sequestration of PDI1A in a calcium depletion-mediated complex with the abundant chaperone calreticulin attenuates the effective concentration of this major lumenal thiol oxidant, providing a plausible and simple mechanism for the observed shift in ER lumenal redox poise upon physiological calcium depletion. Electronic supplementary material The online version of this article (doi:10.1186/s12915-014-0112-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Edward Avezov
- University of Cambridge, Cambridge Institute for Medical Research, Biomedical Campus, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY, United Kingdom.
| | - Tasuku Konno
- University of Cambridge, Cambridge Institute for Medical Research, Biomedical Campus, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY, United Kingdom.
| | - Alisa Zyryanova
- University of Cambridge, Cambridge Institute for Medical Research, Biomedical Campus, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY, United Kingdom.
| | - Weiyue Chen
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB2 3RA, UK.
| | - Romain Laine
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB2 3RA, UK.
| | - Ana Crespillo-Casado
- University of Cambridge, Cambridge Institute for Medical Research, Biomedical Campus, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY, United Kingdom.
| | - Eduardo Pinho Melo
- Center for Biomedical Research, Universidade do Algarve, Faro, Portugal.
| | - Ryo Ushioda
- Faculty of Life Sciences, Kyoto Sangyo University, Kita-Ku, Kyoto-City, 603-8555, Japan.
| | - Kazuhiro Nagata
- Faculty of Life Sciences, Kyoto Sangyo University, Kita-Ku, Kyoto-City, 603-8555, Japan.
| | - Clemens F Kaminski
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB2 3RA, UK.
| | - Heather P Harding
- University of Cambridge, Cambridge Institute for Medical Research, Biomedical Campus, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY, United Kingdom.
| | - David Ron
- University of Cambridge, Cambridge Institute for Medical Research, Biomedical Campus, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY, United Kingdom.
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22
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Tsunoda S, Avezov E, Zyryanova A, Konno T, Mendes-Silva L, Pinho Melo E, Harding HP, Ron D. Intact protein folding in the glutathione-depleted endoplasmic reticulum implicates alternative protein thiol reductants. eLife 2014; 3:e03421. [PMID: 25073928 PMCID: PMC4109312 DOI: 10.7554/elife.03421] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Protein folding homeostasis in the endoplasmic reticulum (ER) requires efficient protein thiol oxidation, but also relies on a parallel reductive process to edit disulfides during the maturation or degradation of secreted proteins. To critically examine the widely held assumption that reduced ER glutathione fuels disulfide reduction, we expressed a modified form of a cytosolic glutathione-degrading enzyme, ChaC1, in the ER lumen. ChaC1CtoS purged the ER of glutathione eliciting the expected kinetic defect in oxidation of an ER-localized glutathione-coupled Grx1-roGFP2 optical probe, but had no effect on the disulfide editing-dependent maturation of the LDL receptor or the reduction-dependent degradation of misfolded alpha-1 antitrypsin. Furthermore, glutathione depletion had no measurable effect on induction of the unfolded protein response (UPR); a sensitive measure of ER protein folding homeostasis. These findings challenge the importance of reduced ER glutathione and suggest the existence of alternative electron donor(s) that maintain the reductive capacity of the ER. DOI:http://dx.doi.org/10.7554/eLife.03421.001 Proteins are basically strings of amino acids that have folded into a specific three-dimensional shape, and this shape is often important for the protein's function. Some proteins have bonds between pairs of cysteines—an amino acid that contains sulfur—in different parts of the protein to maintain its correct shape. In eukaryotes, such as plants and animals, these so-called ‘disulfide bonds’ are formed inside a structure within each cell called the endoplasmic reticulum, which is where many proteins are folded. Occasionally, disulfide bonds form in the wrong place in a protein, so they need to be broken and re-positioned—a process sometimes called editing—for the protein to fold correctly. It was widely assumed that a chemical called ‘reduced glutathione’ fuels the breaking of disulfide bonds in the endoplasmic reticulum, but to date few researchers have tried to test this assumption. Tsunoda et al. have now taken an enzyme that degrades glutathione elsewhere in the cell and modified it in a way that allows it to work inside the endoplasmic reticulum. When this modified enzyme was produced in human cells grown in the laboratory, it purged the endoplasmic reticulum of glutathione. However, the lack of glutathione had no effect on the folding of a large protein with 30 disulfide bonds, many of which need to be edited at one time or another for the protein to fold correctly. The destruction of a poorly folded protein, via a process that also needs this protein's disulfide bonds to be broken down, was also not affected by a lack of reduced glutathione in the endoplasmic reticulum. Furthermore, decreasing these levels of glutathione did not affect the unfolded protein response: a stress response in cells that are experiencing a build-up of unfolded or poorly folded proteins within the endoplasmic reticulum. As such, the findings of Tsunoda et al. challenge the importance of reduced glutathione in the endoplasmic reticulum and suggest that other chemical processes might be involved in editing disulfide bonds. Further work is now needed to investigate the other known processes that might complete this task instead to see which, if any, are involved. DOI:http://dx.doi.org/10.7554/eLife.03421.002
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Affiliation(s)
- Satoshi Tsunoda
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom Wellcome Trust MRC Institute of Metabolic Science, Cambridge, United Kingdom NIHR Cambridge Biomedical Research Centre, Cambridge, United Kingdom
| | - Edward Avezov
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom Wellcome Trust MRC Institute of Metabolic Science, Cambridge, United Kingdom NIHR Cambridge Biomedical Research Centre, Cambridge, United Kingdom
| | - Alisa Zyryanova
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom Wellcome Trust MRC Institute of Metabolic Science, Cambridge, United Kingdom NIHR Cambridge Biomedical Research Centre, Cambridge, United Kingdom
| | - Tasuku Konno
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom Wellcome Trust MRC Institute of Metabolic Science, Cambridge, United Kingdom NIHR Cambridge Biomedical Research Centre, Cambridge, United Kingdom
| | - Leonardo Mendes-Silva
- Centre for Molecular and Structural Biomedicine, Universidade do Algarve, Faro, Portugal
| | - Eduardo Pinho Melo
- Centre for Molecular and Structural Biomedicine, Universidade do Algarve, Faro, Portugal
| | - Heather P Harding
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom Wellcome Trust MRC Institute of Metabolic Science, Cambridge, United Kingdom NIHR Cambridge Biomedical Research Centre, Cambridge, United Kingdom
| | - David Ron
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom Wellcome Trust MRC Institute of Metabolic Science, Cambridge, United Kingdom NIHR Cambridge Biomedical Research Centre, Cambridge, United Kingdom
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23
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Nangalia J, Massie CE, Baxter EJ, Nice FL, Gundem G, Wedge DC, Avezov E, Li J, Kollmann K, Kent DG, Aziz A, Godfrey AL, Hinton J, Martincorena I, Van Loo P, Jones AV, Guglielmelli P, Tarpey P, Harding HP, Fitzpatrick JD, Goudie CT, Ortmann CA, Loughran SJ, Raine K, Jones DR, Butler AP, Teague JW, O'Meara S, McLaren S, Bianchi M, Silber Y, Dimitropoulou D, Bloxham D, Mudie L, Maddison M, Robinson B, Keohane C, Maclean C, Hill K, Orchard K, Tauro S, Du MQ, Greaves M, Bowen D, Huntly BJP, Harrison CN, Cross NCP, Ron D, Vannucchi AM, Papaemmanuil E, Campbell PJ, Green AR. Somatic CALR mutations in myeloproliferative neoplasms with nonmutated JAK2. N Engl J Med 2013; 369:2391-2405. [PMID: 24325359 PMCID: PMC3966280 DOI: 10.1056/nejmoa1312542] [Citation(s) in RCA: 1333] [Impact Index Per Article: 121.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND Somatic mutations in the Janus kinase 2 gene (JAK2) occur in many myeloproliferative neoplasms, but the molecular pathogenesis of myeloproliferative neoplasms with nonmutated JAK2 is obscure, and the diagnosis of these neoplasms remains a challenge. METHODS We performed exome sequencing of samples obtained from 151 patients with myeloproliferative neoplasms. The mutation status of the gene encoding calreticulin (CALR) was assessed in an additional 1345 hematologic cancers, 1517 other cancers, and 550 controls. We established phylogenetic trees using hematopoietic colonies. We assessed calreticulin subcellular localization using immunofluorescence and flow cytometry. RESULTS Exome sequencing identified 1498 mutations in 151 patients, with medians of 6.5, 6.5, and 13.0 mutations per patient in samples of polycythemia vera, essential thrombocythemia, and myelofibrosis, respectively. Somatic CALR mutations were found in 70 to 84% of samples of myeloproliferative neoplasms with nonmutated JAK2, in 8% of myelodysplasia samples, in occasional samples of other myeloid cancers, and in none of the other cancers. A total of 148 CALR mutations were identified with 19 distinct variants. Mutations were located in exon 9 and generated a +1 base-pair frameshift, which would result in a mutant protein with a novel C-terminal. Mutant calreticulin was observed in the endoplasmic reticulum without increased cell-surface or Golgi accumulation. Patients with myeloproliferative neoplasms carrying CALR mutations presented with higher platelet counts and lower hemoglobin levels than patients with mutated JAK2. Mutation of CALR was detected in hematopoietic stem and progenitor cells. Clonal analyses showed CALR mutations in the earliest phylogenetic node, a finding consistent with its role as an initiating mutation in some patients. CONCLUSIONS Somatic mutations in the endoplasmic reticulum chaperone CALR were found in a majority of patients with myeloproliferative neoplasms with nonmutated JAK2. (Funded by the Kay Kendall Leukaemia Fund and others.).
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Avezov E, Cross BCS, Kaminski Schierle GS, Winters M, Harding HP, Melo EP, Kaminski CF, Ron D. Lifetime imaging of a fluorescent protein sensor reveals surprising stability of ER thiol redox. ACTA ACUST UNITED AC 2013; 201:337-49. [PMID: 23589496 PMCID: PMC3628511 DOI: 10.1083/jcb.201211155] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Interfering with disulfide bond formation impedes protein folding and promotes endoplasmic reticulum (ER) stress. Due to limitations in measurement techniques, the relationships of altered thiol redox and ER stress have been difficult to assess. We report that fluorescent lifetime measurements circumvented the crippling dimness of an ER-tuned fluorescent redox-responsive probe (roGFPiE), faithfully tracking the activity of the major ER-localized protein disulfide isomerase, PDI. In vivo lifetime imaging by time-correlated single-photon counting (TCSPC) recorded subtle changes in ER redox poise induced by exposure of mammalian cells to a reducing environment but revealed an unanticipated stability of redox to fluctuations in unfolded protein load. By contrast, TCSPC of roGFPiE uncovered a hitherto unsuspected reductive shift in the mammalian ER upon loss of luminal calcium, whether induced by pharmacological inhibition of calcium reuptake into the ER or by physiological activation of release channels. These findings recommend fluorescent lifetime imaging as a sensitive method to track ER redox homeostasis in mammalian cells.
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Affiliation(s)
- Edward Avezov
- University of Cambridge Metabolic Research Laboratories and NIHR Cambridge Biomedical Research Centre, Cambridge CB2 0QQ, England, UK
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25
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Shenkman M, Groisman B, Ron E, Avezov E, Hendershot LM, Lederkremer GZ. A shared endoplasmic reticulum-associated degradation pathway involving the EDEM1 protein for glycosylated and nonglycosylated proteins. J Biol Chem 2012; 288:2167-78. [PMID: 23233672 DOI: 10.1074/jbc.m112.438275] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Studies of misfolded protein targeting to endoplasmic reticulum-associated degradation (ERAD) have largely focused on glycoproteins, which include the bulk of the secretory proteins. Mechanisms of targeting of nonglycosylated proteins are less clear. Here, we studied three nonglycosylated proteins and analyzed their use of known glycoprotein quality control and ERAD components. Similar to an established glycosylated ERAD substrate, the uncleaved precursor of asialoglycoprotein receptor H2a, its nonglycosylated mutant, makes use of calnexin, EDEM1, and HRD1, but only glycosylated H2a is a substrate for the cytosolic SCF(Fbs2) E3 ubiquitin ligase with lectin activity. Two nonglycosylated BiP substrates, NS-1κ light chain and truncated Igγ heavy chain, interact with the ERAD complex lectins OS-9 and XTP3-B and require EDEM1 for degradation. EDEM1 associates through a region outside of its mannosidase-like domain with the nonglycosylated proteins. Similar to glycosylated substrates, proteasomal inhibition induced accumulation of the nonglycosylated proteins and ERAD machinery in the endoplasmic reticulum-derived quality control compartment. Our results suggest a shared ERAD pathway for glycosylated and nonglycosylated proteins composed of luminal lectin machinery components also capable of protein-protein interactions.
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Affiliation(s)
- Marina Shenkman
- Department of Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
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26
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Avezov E, Ron E, Izenshtein Y, Adan Y, Lederkremer GZ. Pulse-chase analysis of N-linked sugar chains from glycoproteins in mammalian cells. J Vis Exp 2010:1899. [PMID: 20424595 DOI: 10.3791/1899] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Attachment of the Glc3Man9GlcNAc2 precursor oligosaccharide to nascent polypeptides in the ER is a common modification for secretory proteins. Although this modification was implicated in several biological processes, additional aspects of its function are emerging, with recent evidence of its role in the production of signals for glycoprotein quality control and trafficking. Thus, phenomena related to N-linked glycans and their processing are being intensively investigated. Methods that have been recently developed for proteomic analysis have greatly improved the characterization of glycoprotein N-linked glycans. Nevertheless, they do not provide insight into the dynamics of the sugar chain processing involved. For this, labeling and pulse-chase analysis protocols are used that are usually complex and give very low yields. We describe here a simple method for the isolation and analysis of metabolically labeled N-linked oligosaccharides. The protocol is based on labeling of cells with [2-(3)H] mannose, denaturing lysis and enzymatic release of the oligosaccharides from either a specifically immunoprecipitated protein of interest or from the general glycoprotein pool by sequential treatments with endo H and N-glycosidase F, followed by molecular filtration (Amicon). In this method the isolated oligosaccharides serve as an input for HPLC analysis, which allows discrimination between various glycan structures according to the number of monosaccharide units comprising them, with a resolution of a single monosaccharide. Using this method we were able to study high mannose N-linked oligosaccharide profiles of total cell glycoproteins after pulse-chase in normal conditions and under proteasome inhibition. These profiles were compared to those obtained from an immunoprecipitated ER-associated degradation (ERAD) substrate. Our results suggest that most NIH 3T3 cellular glycoproteins are relatively stable and that most of their oligosaccharides are trimmed to Man9-8GlcNAc2. In contrast, unstable ERAD substrates are trimmed to Man6-5GlcNAc2 and glycoproteins bearing these species accumulate upon inhibition of proteasomal degradation.
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27
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Avezov E, Frenkel Z, Ehrlich M, Herscovics A, Lederkremer GZ. Endoplasmic reticulum (ER) mannosidase I is compartmentalized and required for N-glycan trimming to Man5-6GlcNAc2 in glycoprotein ER-associated degradation. Mol Biol Cell 2007; 19:216-25. [PMID: 18003979 DOI: 10.1091/mbc.e07-05-0505] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
We had previously shown that endoplasmic reticulum (ER)-associated degradation (ERAD) of glycoproteins in mammalian cells involves trimming of three to four mannose residues from the N-linked oligosaccharide Man(9)GlcNAc(2). A possible candidate for this activity, ER mannosidase I (ERManI), accelerates the degradation of ERAD substrates when overexpressed. Although in vitro, at low concentrations, ERManI removes only one specific mannose residue, at very high concentrations it can excise up to four alpha1,2-linked mannose residues. Using small interfering RNA knockdown of ERManI, we show that this enzyme is required for trimming to Man(5-6)GlcNAc(2) and for ERAD in cells in vivo, leading to the accumulation of Man(9)GlcNAc(2) and Glc(1)Man(9)GlcNAc(2) on a model substrate. Thus, trimming by ERManI to the smaller oligosaccharides would remove the glycoprotein from reglucosylation and calnexin binding cycles. ERManI is strikingly concentrated together with the ERAD substrate in the pericentriolar ER-derived quality control compartment (ERQC) that we had described previously. ERManI knockdown prevents substrate accumulation in the ERQC. We suggest that the ERQC provides a high local concentration of ERManI, and passage through this compartment would allow timing of ERAD, possibly through a cycling mechanism. When newly made glycoproteins cannot fold properly, transport through the ERQC leads to trimming of a critical number of mannose residues, triggering a signal for degradation.
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Affiliation(s)
- Edward Avezov
- Department of Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
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Kondratyev M, Avezov E, Shenkman M, Groisman B, Lederkremer GZ. PERK-dependent compartmentalization of ERAD and unfolded protein response machineries during ER stress. Exp Cell Res 2007; 313:3395-407. [PMID: 17707796 DOI: 10.1016/j.yexcr.2007.07.006] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2006] [Revised: 07/06/2007] [Accepted: 07/07/2007] [Indexed: 01/22/2023]
Abstract
Accumulation of misfolded proteins in the endoplasmic reticulum (ER) activates the ER membrane kinases PERK and IRE1 leading to the unfolded protein response (UPR). We show here that UPR activation triggers PERK and IRE1 segregation from BiP and their sorting with misfolded proteins to the ER-derived quality control compartment (ERQC), a pericentriolar compartment that we had identified previously. PERK phosphorylates translation factor eIF2alpha, which then accumulates on the cytosolic side of the ERQC. Dominant negative PERK or eIF2alpha(S51A) mutants prevent the compartmentalization, whereas eIF2alpha(S51D) mutant, which mimics constitutive phosphorylation, promotes it. This suggests a feedback loop where eIF2alpha phosphorylation causes pericentriolar concentration at the ERQC, which in turn amplifies the UPR. ER-associated degradation (ERAD) is an UPR-dependent process; we also find that ERAD components (Sec61beta, HRD1, p97/VCP, ubiquitin) are recruited to the ERQC, making it a likely site for retrotranslocation. In addition, we show that autophagy, suggested to play a role in elimination of aggregated proteins, is unrelated to protein accumulation in the ERQC.
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Affiliation(s)
- Maria Kondratyev
- Department of Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
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Groisman B, Avezov E, Lederkremer GZ. The E3 Ubiquitin Ligases HRD1 and SCFFbs2Recognize the Protein Moiety and Sugar Chains, Respectively, of an ER-Associated Degradation Substrate. Isr J Chem 2006. [DOI: 10.1560/2qpd-9wp9-ncyk-58x3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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