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Hall BS, Dos Santos SJ, Hsieh LTH, Manifava M, Ruf MT, Pluschke G, Ktistakis N, Simmonds RE. Inhibition of the SEC61 translocon by mycolactone induces a protective autophagic response controlled by EIF2S1-dependent translation that does not require ULK1 activity. Autophagy 2021; 18:841-859. [PMID: 34424124 PMCID: PMC9037441 DOI: 10.1080/15548627.2021.1961067] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The Mycobacterium ulcerans exotoxin, mycolactone, is responsible for the immunosuppression and tissue necrosis that characterizes Buruli ulcer. Mycolactone inhibits SEC61-dependent co-translational translocation of proteins into the endoplasmic reticulum and the resultant cytosolic translation triggers degradation of mislocalized proteins by the ubiquitin-proteasome system. Inhibition of SEC61 by mycolactone also activates multiple EIF2S1/eIF2α kinases in the integrated stress response (ISR). Here we show mycolactone increased canonical markers of selective macroautophagy/autophagy LC3B-II, ubiquitin and SQSTM1/p62 in diverse disease-relevant primary cells and cell lines. Increased formation of puncta positive for the early autophagy markers WIPI2, RB1CC1/FIP200 and ATG16L1 indicates increased initiation of autophagy. The mycolactone response was SEC61A1-dependent and involved a pathway that required RB1CC1 but not ULK. Deletion of Sqstm1 reduced cell survival in the presence of mycolactone, suggesting this response protects against the increased cytosolic protein burden caused by the toxin. However, reconstitution of baseline SQSTM1 expression in cells lacking all autophagy receptor proteins could not rescue viability. Translational regulation by EIF2S1 in the ISR plays a key role in the autophagic response to mycolactone. Mycolactone-dependent induction of SQSTM1 was reduced in eif2ak3−/-/perk−/- cells while the p-EIF2S1 antagonist ISRIB reversed the upregulation of SQSTM1 and reduced RB1CC1, WIPI2 and LC3B puncta formation. Increased SQSTM1 staining could be seen in Buruli ulcer patient skin biopsy samples, reinforcing genetic data that suggests autophagy is relevant to disease pathology. Since selective autophagy and the ISR are both implicated in neurodegeneration, cancer and inflammation, the pathway uncovered here may have a broad relevance to human disease. Abbreviations: ATF4: activating transcription factor 4; ATG: autophagy related; BAF: bafilomycin A1; ATG16L1: autophagy related 16 like 1; BU: Buruli ulcer; CQ: chloroquine; EIF2AK3: eukaryotic translation initiation factor 2 alpha kinase 3; CALCOCO2: calcium binding and coiled-coil domain 2; DMSO: dimethyl sulfoxide; EIF2S1: eukaryotic translation initiation factor 2 subunit alpha; ER: endoplasmic reticulum; GFP: green fluorescent protein; HDMEC: human dermal microvascular endothelial cells; HFFF: human fetal foreskin fibroblasts; ISR: integrated stress response; ISRIB: integrated stress response inhibitor; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MEF: mouse embryonic fibroblast; Myco: mycolactone; NBR1: NBR1 autophagy cargo receptor; NFE2L2: nuclear factor, erythroid 2 like 2; OPTN: optineurin; PFA: paraformaldehyde; PtdIns3P: phosphatidylinositol-3-phosphate; RB1CC1: RB1-inducible coiled coil 1; SQSTM1: sequestosome 1; TAX1BP1: Tax1 binding protein 1; ULK: unc-51 like autophagy activating kinase; UPS: ubiquitin-proteasome system; WIPI: WD repeat domain, phosphoinositide interacting; WT: wild type.
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Affiliation(s)
- Belinda S Hall
- Department of Microbial Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, UK
| | - Scott J Dos Santos
- Department of Microbial Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, UK
| | - Louise Tzung-Harn Hsieh
- Department of Microbial Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, UK
| | | | - Marie-Thérèse Ruf
- Molecular Immunology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,Medical Parasitology and Infection Biology Department, University of Basel, Basel, Switzerland
| | - Gerd Pluschke
- Molecular Immunology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,Medical Parasitology and Infection Biology Department, University of Basel, Basel, Switzerland
| | | | - Rachel E Simmonds
- Department of Microbial Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, UK
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Zong G, Hu Z, O’Keefe S, Tranter D, Iannotti MJ, Baron L, Hall B, Corfield K, Paatero AO, Henderson MJ, Roboti P, Zhou J, Sun X, Govindarajan M, Rohde JM, Blanchard N, Simmonds R, Inglese J, Du Y, Demangel C, High S, Paavilainen VO, Shi WQ. Ipomoeassin F Binds Sec61α to Inhibit Protein Translocation. J Am Chem Soc 2019; 141:8450-8461. [PMID: 31059257 PMCID: PMC6627486 DOI: 10.1021/jacs.8b13506] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Ipomoeassin F is a potent natural cytotoxin that inhibits growth of many tumor cell lines with single-digit nanomolar potency. However, its biological and pharmacological properties have remained largely unexplored. Building upon our earlier achievements in total synthesis and medicinal chemistry, we used chemical proteomics to identify Sec61α (protein transport protein Sec61 subunit alpha isoform 1), the pore-forming subunit of the Sec61 protein translocon, as a direct binding partner of ipomoeassin F in living cells. The interaction is specific and strong enough to survive lysis conditions, enabling a biotin analogue of ipomoeassin F to pull down Sec61α from live cells, yet it is also reversible, as judged by several experiments including fluorescent streptavidin staining, delayed competition in affinity pulldown, and inhibition of TNF biogenesis after washout. Sec61α forms the central subunit of the ER protein translocation complex, and the binding of ipomoeassin F results in a substantial, yet selective, inhibition of protein translocation in vitro and a broad ranging inhibition of protein secretion in live cells. Lastly, the unique resistance profile demonstrated by specific amino acid single-point mutations in Sec61α provides compelling evidence that Sec61α is the primary molecular target of ipomoeassin F and strongly suggests that the binding of this natural product to Sec61α is distinctive. Therefore, ipomoeassin F represents the first plant-derived, carbohydrate-based member of a novel structural class that offers new opportunities to explore Sec61α function and to further investigate its potential as a therapeutic target for drug discovery.
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Affiliation(s)
- Guanghui Zong
- †Department
of Chemistry and Biochemistry and ⬡Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, United States,Department
of Chemistry and Biochemistry, University
of Maryland, College Park, Maryland 20742, United States
| | - Zhijian Hu
- †Department
of Chemistry and Biochemistry and ⬡Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, United States
| | - Sarah O’Keefe
- School
of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, United Kingdom
| | - Dale Tranter
- University
of Helsinki, HiLIFE, Helsinki, Finland,Institute
of Biotechnology, Helsinki, Finland
| | - Michael J. Iannotti
- National
Center for Advancing Translational Sciences, National
Institutes of Health, Rockville, Maryland 20850, United States
| | - Ludivine Baron
- Immunobiology
of Infection Unit, Institut Pasteur, 75015 Paris, France,INSERM, U1221, 75005 Paris, France
| | - Belinda Hall
- Department
of Microbial Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom
| | - Katherine Corfield
- Department
of Microbial Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom
| | - Anja O. Paatero
- University
of Helsinki, HiLIFE, Helsinki, Finland,Institute
of Biotechnology, Helsinki, Finland
| | - Mark J. Henderson
- National
Center for Advancing Translational Sciences, National
Institutes of Health, Rockville, Maryland 20850, United States
| | - Peristera Roboti
- School
of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, United Kingdom
| | - Jianhong Zhou
- †Department
of Chemistry and Biochemistry and ⬡Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, United States
| | - Xianwei Sun
- †Department
of Chemistry and Biochemistry and ⬡Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, United States,Department
of Radiology, Baylor College of Medicine, Houston, Texas 77030, United States
| | - Mugunthan Govindarajan
- †Department
of Chemistry and Biochemistry and ⬡Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, United States,Emory
Institute for Drug Development, Emory University, 954 Gatewood Road, Atlanta, Georgia 30329, United States
| | - Jason M. Rohde
- National
Center for Advancing Translational Sciences, National
Institutes of Health, Rockville, Maryland 20850, United States
| | - Nicolas Blanchard
- Université
de Haute-Alsace, Université de Strasbourg, CNRS, LIMA, UMR 7042, 68000 Mulhouse, France
| | - Rachel Simmonds
- Department
of Microbial Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom,
| | - James Inglese
- National
Center for Advancing Translational Sciences, National
Institutes of Health, Rockville, Maryland 20850, United States,
| | - Yuchun Du
- †Department
of Chemistry and Biochemistry and ⬡Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, United States,
| | - Caroline Demangel
- Immunobiology
of Infection Unit, Institut Pasteur, 75015 Paris, France,INSERM, U1221, 75005 Paris, France,
| | - Stephen High
- School
of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, United Kingdom,
| | - Ville O. Paavilainen
- University
of Helsinki, HiLIFE, Helsinki, Finland,Institute
of Biotechnology, Helsinki, Finland,
| | - Wei Q. Shi
- †Department
of Chemistry and Biochemistry and ⬡Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, United States,Department
of Chemistry, Ball State University, Muncie, Indiana 47306, United States,;
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