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Wysocki R, Rodrigues JI, Litwin I, Tamás MJ. Mechanisms of genotoxicity and proteotoxicity induced by the metalloids arsenic and antimony. Cell Mol Life Sci 2023; 80:342. [PMID: 37904059 PMCID: PMC10616229 DOI: 10.1007/s00018-023-04992-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 09/12/2023] [Accepted: 09/29/2023] [Indexed: 11/01/2023]
Abstract
Arsenic and antimony are metalloids with profound effects on biological systems and human health. Both elements are toxic to cells and organisms, and exposure is associated with several pathological conditions including cancer and neurodegenerative disorders. At the same time, arsenic- and antimony-containing compounds are used in the treatment of multiple diseases. Although these metalloids can both cause and cure disease, their modes of molecular action are incompletely understood. The past decades have seen major advances in our understanding of arsenic and antimony toxicity, emphasizing genotoxicity and proteotoxicity as key contributors to pathogenesis. In this review, we highlight mechanisms by which arsenic and antimony cause toxicity, focusing on their genotoxic and proteotoxic effects. The mechanisms used by cells to maintain proteostasis during metalloid exposure are also described. Furthermore, we address how metalloid-induced proteotoxicity may promote neurodegenerative disease and how genotoxicity and proteotoxicity may be interrelated and together contribute to proteinopathies. A deeper understanding of cellular toxicity and response mechanisms and their links to pathogenesis may promote the development of strategies for both disease prevention and treatment.
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Affiliation(s)
- Robert Wysocki
- Department of Genetics and Cell Physiology, Faculty of Biological Sciences, University of Wroclaw, 50-328, Wroclaw, Poland.
| | - Joana I Rodrigues
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, 405 30, Göteborg, Sweden
| | - Ireneusz Litwin
- Academic Excellence Hub - Research Centre for DNA Repair and Replication, Faculty of Biological Sciences, University of Wroclaw, 50-328, Wroclaw, Poland
| | - Markus J Tamás
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, 405 30, Göteborg, Sweden.
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2
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Walsh RM, Rawson S, Schnell HM, Velez B, Rajakumar T, Hanna J. Structure of the preholoproteasome reveals late steps in proteasome core particle biogenesis. Nat Struct Mol Biol 2023; 30:1516-1524. [PMID: 37653242 PMCID: PMC10879985 DOI: 10.1038/s41594-023-01081-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 07/26/2023] [Indexed: 09/02/2023]
Abstract
Assembly of the proteasome's core particle (CP), a barrel-shaped chamber of four stacked rings, requires five chaperones and five subunit propeptides. Fusion of two half-CP precursors yields a complete structure but remains immature until active site maturation. Here, using Saccharomyces cerevisiae, we report a high-resolution cryogenic electron microscopy structure of preholoproteasome, a post-fusion assembly intermediate. Our data reveal how CP midline-spanning interactions induce local changes in structure, facilitating maturation. Unexpectedly, we find that cleavage may not be sufficient for propeptide release, as residual interactions with chaperones such as Ump1 hold them in place. We evaluated previous models proposing that dynamic conformational changes in chaperones drive CP fusion and autocatalytic activation by comparing preholoproteasome to pre-fusion intermediates. Instead, the data suggest a scaffolding role for the chaperones Ump1 and Pba1/Pba2. Our data clarify key aspects of CP assembly, suggest that undiscovered mechanisms exist to explain CP fusion/activation, and have relevance for diseases of defective CP biogenesis.
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Affiliation(s)
- Richard M Walsh
- Harvard Cryo-Electron Microscopy Center for Structural Biology, Harvard Medical School, Boston, MA, USA
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Shaun Rawson
- Harvard Cryo-Electron Microscopy Center for Structural Biology, Harvard Medical School, Boston, MA, USA
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Helena M Schnell
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA
| | - Benjamin Velez
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA
| | - Tamayanthi Rajakumar
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA
| | - John Hanna
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA.
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3
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Karska J, Kowalski S, Saczko J, Moisescu MG, Kulbacka J. Mechanosensitive Ion Channels and Their Role in Cancer Cells. MEMBRANES 2023; 13:167. [PMID: 36837670 PMCID: PMC9965697 DOI: 10.3390/membranes13020167] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 01/25/2023] [Accepted: 01/26/2023] [Indexed: 06/18/2023]
Abstract
Mechanical forces are an inherent element in the world around us. The effects of their action can be observed both on the macro and molecular levels. They can also play a prominent role in the tissues and cells of animals due to the presence of mechanosensitive ion channels (MIChs) such as the Piezo and TRP families. They are essential in many physiological processes in the human body. However, their role in pathology has also been observed. Recent discoveries have highlighted the relationship between these channels and the development of malignant tumors. Multiple studies have shown that MIChs mediate the proliferation, migration, and invasion of various cancer cells via various mechanisms. This could show MIChs as new potential biomarkers in cancer detection and prognosis and interesting therapeutic targets in modern oncology. Our paper is a review of the latest literature on the role of the Piezo1 and TRP families in the molecular mechanisms of carcinogenesis in different types of cancer.
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Affiliation(s)
- Julia Karska
- Faculty of Medicine, Wroclaw Medical University, 50-345 Wroclaw, Poland
| | - Szymon Kowalski
- Faculty of Medicine, Wroclaw Medical University, 50-345 Wroclaw, Poland
| | - Jolanta Saczko
- Department of Molecular and Cellular Biology, Faculty of Pharmacy, Wroclaw Medical University, 50-556 Wroclaw, Poland
| | - Mihaela G. Moisescu
- Department of Biophysics and Cellular Biotechnology, Research Center of Excellence in Biophysics and Cellular Biotechnology, Faculty of Medicine, Carol Davila University of Medicine and Pharmacy, 050474 Bucharest, Romania
| | - Julita Kulbacka
- Department of Molecular and Cellular Biology, Faculty of Pharmacy, Wroclaw Medical University, 50-556 Wroclaw, Poland
- Department of Immunology, State Research Institute Centre for Innovative Medicine, 08406 Vilnius, Lithuania
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4
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Yeast PI31 inhibits the proteasome by a direct multisite mechanism. Nat Struct Mol Biol 2022; 29:791-800. [PMID: 35927584 PMCID: PMC9399903 DOI: 10.1038/s41594-022-00808-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 06/24/2022] [Indexed: 02/06/2023]
Abstract
Proteasome inhibitors are widely used as therapeutics and research tools, and typically target one of the three active sites, each present twice in the proteasome complex. An endogeneous proteasome inhibitor, PI31, was identified 30 years ago, but its inhibitory mechanism has remained unclear. Here, we identify the mechanism of Saccharomyces cerevisiae PI31, also known as Fub1. Using cryo-electron microscopy (cryo-EM), we show that the conserved carboxy-terminal domain of Fub1 is present inside the proteasome's barrel-shaped core particle (CP), where it simultaneously interacts with all six active sites. Targeted mutations of Fub1 disrupt proteasome inhibition at one active site, while leaving the other sites unaffected. Fub1 itself evades degradation through distinct mechanisms at each active site. The gate that allows substrates to access the CP is constitutively closed, and Fub1 is enriched in mutant CPs with an abnormally open gate, suggesting that Fub1 may function to neutralize aberrant proteasomes, thereby ensuring the fidelity of proteasome-mediated protein degradation.
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5
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Schnell HM, Jochem M, Micoogullari Y, Riggs CL, Ivanov P, Welsch H, Ravindran R, Anderson P, Robinson LC, Tatchell K, Hanna J. Reg1 and Snf1 regulate stress-induced relocalization of protein phosphatase-1 to cytoplasmic granules. FEBS J 2021; 288:4833-4848. [PMID: 33682330 DOI: 10.1111/febs.15802] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 02/22/2021] [Accepted: 03/03/2021] [Indexed: 11/26/2022]
Abstract
The compartmentalization of cellular function is achieved largely through the existence of membrane-bound organelles. However, recent work suggests a novel mechanism of compartmentalization mediated by membraneless structures that have liquid droplet-like properties and arise through phase separation. Cytoplasmic stress granules (SGs) are the best characterized and are induced by various stressors including arsenite, heat shock, and glucose deprivation. Current models suggest that SGs play an important role in protein homeostasis by mediating reversible translation attenuation. Protein phosphatase-1 (PP1) is a central cellular regulator responsible for most serine/threonine dephosphorylation. Here, we show that upon arsenite stress, PP1's catalytic subunit Glc7 relocalizes to punctate cytoplasmic granules. This altered localization requires PP1's recently described maturation pathway mediated by the multifunctional ATPase Cdc48 and PP1's regulatory subunit Ypi1. Glc7 relocalization is mediated by its regulatory subunit Reg1 and its target Snf1, the AMP-dependent protein kinase. Surprisingly, Glc7 granules are highly specific to arsenite and appear distinct from canonical SGs. Arsenite induces potent translational inhibition, and translational recovery is strongly dependent on Glc7, but independent of Glc7's well-established role in regulating eIF2α. These results suggest a novel form of stress-induced cytoplasmic granule and a new mode of translational control by Glc7.
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Affiliation(s)
- Helena Maria Schnell
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA
| | - Marco Jochem
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA
| | - Yagmur Micoogullari
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA
| | - Claire Louise Riggs
- Department of Rheumatology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA
| | - Pavel Ivanov
- Department of Rheumatology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA
| | - Hendrik Welsch
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA
| | - Rini Ravindran
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA, USA
| | - Paul Anderson
- Department of Rheumatology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA
| | - Lucy Christina Robinson
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA, USA
| | - Kelly Tatchell
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA, USA
| | - John Hanna
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA
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6
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Guerra-Moreno A, Prado MA, Ang J, Schnell HM, Micoogullari Y, Paulo JA, Finley D, Gygi SP, Hanna J. Thiol-based direct threat sensing by the stress-activated protein kinase Hog1. Sci Signal 2019; 12:12/609/eaaw4956. [PMID: 31772124 DOI: 10.1126/scisignal.aaw4956] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The yeast stress-activated protein kinase Hog1 is best known for its role in mediating the response to osmotic stress, but it is also activated by various mechanistically distinct environmental stressors, including heat shock, endoplasmic reticulum stress, and arsenic. In the osmotic stress response, the signal is sensed upstream and relayed to Hog1 through a kinase cascade. Here, we identified a mode of Hog1 function whereby Hog1 senses arsenic through a direct physical interaction that requires three conserved cysteine residues located adjacent to the catalytic loop. These residues were essential for Hog1-mediated protection against arsenic, were dispensable for the response to osmotic stress, and promoted the nuclear localization of Hog1 upon exposure of cells to arsenic. Hog1 promoted arsenic detoxification by stimulating phosphorylation of the transcription factor Yap8, promoting Yap8 nuclear localization, and stimulating the transcription of the only known Yap8 targets, ARR2 and ARR3, both of which encode proteins that promote arsenic efflux. The related human kinases ERK1 and ERK2 also bound to arsenic in vitro, suggesting that this may be a conserved feature of some members of the mitogen-activated protein kinase (MAPK) family. These data provide a mechanistic basis for understanding how stress-activated kinases can sense distinct threats and perform highly specific adaptive responses.
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Affiliation(s)
- Angel Guerra-Moreno
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Miguel A Prado
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Jessie Ang
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Helena M Schnell
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Yagmur Micoogullari
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Joao A Paulo
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Daniel Finley
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Steven P Gygi
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - John Hanna
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
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7
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Micoogullari Y, Basu SS, Ang J, Weisshaar N, Schmitt ND, Abdelmoula WM, Lopez B, Agar JN, Agar N, Hanna J. Dysregulation of very-long-chain fatty acid metabolism causes membrane saturation and induction of the unfolded protein response. Mol Biol Cell 2019; 31:7-17. [PMID: 31746669 PMCID: PMC6938273 DOI: 10.1091/mbc.e19-07-0392] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The unfolded protein response (UPR) senses defects in the endoplasmic reticulum (ER) and orchestrates a complex program of adaptive cellular remodeling. Increasing evidence suggests an important relationship between lipid homeostasis and the UPR. Defects in the ER membrane induce the UPR, and the UPR in turn controls the expression of some lipid metabolic genes. Among lipid species, the very-long-chain fatty acids (VLCFAs) are relatively rare and poorly understood. Here, we show that loss of the VLCFA-coenzyme A synthetase Fat1, which is essential for VLCFA utilization, results in ER stress with compensatory UPR induction. Comprehensive lipidomic analyses revealed a dramatic increase in membrane saturation in the fat1Δ mutant, likely accounting for UPR induction. In principle, this increased membrane saturation could reflect adaptive membrane remodeling or an adverse effect of VLCFA dysfunction. We provide evidence supporting the latter, as the fat1Δ mutant showed defects in the function of Ole1, the sole fatty acyl desaturase in yeast. These results indicate that VLCFAs play essential roles in protein quality control and membrane homeostasis and suggest an unexpected requirement for VLCFAs in Ole1 function.
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Affiliation(s)
| | - Sankha S Basu
- Department of Neurosurgery, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115
| | | | | | | | - Walid M Abdelmoula
- Department of Neurosurgery, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115
| | - Begona Lopez
- Department of Neurosurgery, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115
| | - Jeffrey N Agar
- Department of Chemistry and Chemical Biology and.,Department of Pharmacological Sciences, Northeastern University, Boston, MA 02111
| | - Nathalie Agar
- Department of Neurosurgery, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115
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8
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Jochem M, Ende L, Isasa M, Ang J, Schnell H, Guerra-Moreno A, Micoogullari Y, Bhanu M, Gygi SP, Hanna J. Targeted Degradation of Glucose Transporters Protects against Arsenic Toxicity. Mol Cell Biol 2019; 39:e00559-18. [PMID: 30886123 PMCID: PMC6497993 DOI: 10.1128/mcb.00559-18] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 12/12/2018] [Accepted: 03/12/2019] [Indexed: 12/29/2022] Open
Abstract
The abundance of cell surface glucose transporters must be precisely regulated to ensure optimal growth under constantly changing environmental conditions. We recently conducted a proteomic analysis of the cellular response to trivalent arsenic, a ubiquitous environmental toxin and carcinogen. A surprising finding was that a subset of glucose transporters was among the most downregulated proteins in the cell upon arsenic exposure. Here we show that this downregulation reflects targeted arsenic-dependent degradation of glucose transporters. Degradation occurs in the vacuole and requires the E2 ubiquitin ligase Ubc4, the E3 ubiquitin ligase Rsp5, and K63-linked ubiquitin chains. We used quantitative proteomic approaches to determine the ubiquitinated proteome after arsenic exposure, which helped us to identify the ubiquitination sites within these glucose transporters. A mutant lacking all seven major glucose transporters was highly resistant to arsenic, and expression of a degradation-resistant transporter restored arsenic sensitivity to this strain, suggesting that this pathway represents a protective cellular response. Previous work suggests that glucose transporters are major mediators of arsenic import, providing a potential rationale for this pathway. These results may have implications for the epidemiologic association between arsenic exposure and diabetes.
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Affiliation(s)
- Marco Jochem
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Lukas Ende
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Marta Isasa
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA
| | - Jessie Ang
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Helena Schnell
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Angel Guerra-Moreno
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Yagmur Micoogullari
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Meera Bhanu
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Steven P Gygi
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA
| | - John Hanna
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
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9
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Guerra-Moreno A, Ang J, Welsch H, Jochem M, Hanna J. Regulation of the unfolded protein response in yeast by oxidative stress. FEBS Lett 2019; 593:1080-1088. [PMID: 31002390 DOI: 10.1002/1873-3468.13389] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 04/09/2019] [Accepted: 04/11/2019] [Indexed: 12/11/2022]
Abstract
In the unfolded protein response (UPR), Ire1 activates Hac1 to coordinate the transcription of hundreds of genes to mitigate ER stress. Recent work in Caenorhabditis elegans suggests that oxidative stress inhibits this canonical Ire1 signalling pathway, activating instead an antioxidant stress response. We sought to determine whether this novel mode of UPR function also existed in yeast, where Ire1 has been best characterized. We show that the yeast UPR is also subject to inhibition by oxidative stress. Inhibition is mediated by a single evolutionarily conserved cysteine, and affects both luminal and membrane pathways of Ire1 activation. In yeast, Ire1 appears dispensable for resistance to oxidative stress and, therefore, the physiological significance of this pathway remains to be demonstrated.
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Affiliation(s)
- Angel Guerra-Moreno
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Jessie Ang
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Hendrik Welsch
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Marco Jochem
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - John Hanna
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
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10
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Karpov DS, Spasskaya DS, Nadolinskaia NI, Tutyaeva VV, Lysov YP, Karpov VL. Deregulation of the 19S proteasome complex increases yeast resistance to 4-NQO and oxidative stress via upregulation of Rpn4- and proteasome-dependent stress responsive genes. FEMS Yeast Res 2019; 19:5281435. [DOI: 10.1093/femsyr/foz002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 01/05/2019] [Indexed: 01/07/2023] Open
Affiliation(s)
- Dmitry S Karpov
- Department of Intracellular proteolysis regulation, Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov str. 32, Moscow 119991, Russia
- Laboratory of Medicinal Proteomics, Orekhovich Institute of Biomedical Chemistry, Pogodinskaya str. 10, Moscow 119121, Russia
| | - Daria S Spasskaya
- Department of Intracellular proteolysis regulation, Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov str. 32, Moscow 119991, Russia
| | - Nonna I Nadolinskaia
- Department of Intracellular proteolysis regulation, Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov str. 32, Moscow 119991, Russia
| | - Vera V Tutyaeva
- Department of Intracellular proteolysis regulation, Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov str. 32, Moscow 119991, Russia
| | - Yuriy P Lysov
- Department of Intracellular proteolysis regulation, Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov str. 32, Moscow 119991, Russia
| | - Vadim L Karpov
- Department of Intracellular proteolysis regulation, Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov str. 32, Moscow 119991, Russia
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11
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Guerra-Moreno A, Hanna J. Induction of proteotoxic stress by the mycotoxin patulin. Toxicol Lett 2017; 276:85-91. [PMID: 28529145 DOI: 10.1016/j.toxlet.2017.05.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 04/24/2017] [Accepted: 05/14/2017] [Indexed: 01/04/2023]
Abstract
Patulin is a naturally occurring mycotoxin produced by a number of molds and may contaminate a wide variety of food products. In practice, patulin's main societal relevance concerns apple juice and its products. Multiple advisory bodies, including the U.S. Food and Drug Administration and the World Health Organization, recommend that producers monitor and limit patulin levels in apple juice products. The mechanism of patulin toxicity remains largely unknown. Here we show that patulin induces proteotoxic stress in the yeast S. cerevisiae. The transcription factor Rpn4 controls the abundance of the proteasome, the complex multisubunit protease that destroys proteins, including misfolded proteins. Rpn4 protein is strongly induced by patulin, and Rpn4 levels normalize over time, consistent with homeostatic regulation. A rpn4Δ mutant is highly sensitive to patulin, confirming the physiologic relevance of this response. Rpn4 is known to be regulated both transcriptionally and post-translationally. Patulin induces both pathways of regulation, but the post-transcriptional pathway predominates in controlling Rpn4 protein levels. These results indicate that proteotoxicity represents a major aspect of patulin toxicity. They not only have implications for patulin detoxification but in addition suggest the possibility of some potentially useful patulin applications.
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Affiliation(s)
- Angel Guerra-Moreno
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, United States
| | - John Hanna
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, United States.
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12
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Weisshaar N, Welsch H, Guerra-Moreno A, Hanna J. Phospholipase Lpl1 links lipid droplet function with quality control protein degradation. Mol Biol Cell 2017; 28:716-725. [PMID: 28100635 PMCID: PMC5349779 DOI: 10.1091/mbc.e16-10-0717] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 01/05/2017] [Accepted: 01/09/2017] [Indexed: 11/11/2022] Open
Abstract
Protein misfolding is toxic to cells and is believed to underlie many human diseases, including many neurodegenerative diseases. Accordingly, cells have developed stress responses to deal with misfolded proteins. The transcription factor Rpn4 mediates one such response and is best known for regulating the abundance of the proteasome, the complex multisubunit protease that destroys proteins. Here we identify Lpl1 as an unexpected target of the Rpn4 response. Lpl1 is a phospholipase and a component of the lipid droplet. Lpl1 has dual functions: it is required for both efficient proteasome-mediated protein degradation and the dynamic regulation of lipid droplets. Lpl1 shows a synthetic genetic interaction with Hac1, the master regulator of a second proteotoxic stress response, the unfolded protein response (UPR). The UPR has long been known to regulate phospholipid metabolism, and Lpl1's relationship with Hac1 appears to reflect Hac1's role in stimulating phospholipid synthesis under stress. Thus two distinct proteotoxic stress responses control phospholipid metabolism. Furthermore, these results provide a direct link between the lipid droplet and proteasomal protein degradation and suggest that dynamic regulation of lipid droplets is a key aspect of some proteotoxic stress responses.
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Affiliation(s)
- Nina Weisshaar
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115
| | - Hendrik Welsch
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115
| | - Angel Guerra-Moreno
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115
| | - John Hanna
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115
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