1
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Aalto A, Martínez‐Chacón G, Kietz C, Tsyganova N, Kreutzer J, Kallio P, Broemer M, Meinander A. M1-linked ubiquitination facilitates NF-κB activation and survival during sterile inflammation. FEBS J 2022; 289:5180-5197. [PMID: 35263507 PMCID: PMC9543601 DOI: 10.1111/febs.16425] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [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: 06/11/2021] [Revised: 12/17/2021] [Accepted: 03/07/2022] [Indexed: 01/03/2023]
Abstract
Methionine 1 (M1)-linked ubiquitination plays a key role in the regulation of inflammatory nuclear factor-κB (NF-κB) signalling and is important for clearance of pathogen infection in Drosophila melanogaster. M1-linked ubiquitin (M1-Ub) chains are assembled by the linear ubiquitin E3 ligase (LUBEL) in flies. Here, we have studied the role of LUBEL in sterile inflammation induced by different types of cellular stresses. We have found that the LUBEL catalyses formation of M1-Ub chains in response to hypoxic, oxidative and mechanical stress conditions. LUBEL is shown to be important for flies to survive low oxygen conditions and paraquat-induced oxidative stress. This protective action seems to be driven by stress-induced activation of the NF-κB transcription factor Relish via the immune deficiency (Imd) pathway. In addition to LUBEL, the intracellular mediators of Relish activation, including the transforming growth factor activating kinase 1 (Tak1), Drosophila inhibitor of apoptosis (IAP) Diap2, the IκB kinase γ (IKKγ) Kenny and the initiator caspase Death-related ced-3/Nedd2-like protein (Dredd), but not the membrane receptor peptidoglycan recognition protein (PGRP)-LC, are shown to be required for sterile inflammatory response and survival. Finally, we showed that the stress-induced upregulation of M1-Ub chains in response to hypoxia, oxidative and mechanical stress is also induced in mammalian cells and protects from stress-induced cell death. Taken together, our results suggest that M1-Ub chains are important for NF-κB signalling in inflammation induced by stress conditions often observed in chronic inflammatory diseases and cancer.
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Affiliation(s)
- Anna Aalto
- Faculty of Science and Engineering, Cell BiologyÅbo Akademi University, BioCityTurkuFinland
| | | | - Christa Kietz
- Faculty of Science and Engineering, Cell BiologyÅbo Akademi University, BioCityTurkuFinland
| | - Nadezhda Tsyganova
- Faculty of Science and Engineering, Cell BiologyÅbo Akademi University, BioCityTurkuFinland
| | - Joose Kreutzer
- Faculty of Medicine and Health TechnologyBioMediTechTampere UniversityFinland
| | - Pasi Kallio
- Faculty of Medicine and Health TechnologyBioMediTechTampere UniversityFinland
| | - Meike Broemer
- German Center for Neurodegenerative Diseases (DZNE)BonnGermany
| | - Annika Meinander
- Faculty of Science and Engineering, Cell BiologyÅbo Akademi University, BioCityTurkuFinland
- InFLAMES Research Flagship CenterÅbo Akademi UniversityTurkuFinland
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2
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Das R, Schwintzer L, Vinopal S, Aguado Roca E, Sylvester M, Oprisoreanu AM, Schoch S, Bradke F, Broemer M. New roles for the de-ubiquitylating enzyme OTUD4 in an RNA-protein network and RNA granules. J Cell Sci 2019; 132:jcs.229252. [PMID: 31138677 PMCID: PMC6602300 DOI: 10.1242/jcs.229252] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 05/11/2019] [Indexed: 11/20/2022] Open
Abstract
Mechanisms that regulate the formation of membrane-less cellular organelles, such as neuronal RNA granules and stress granules, have gained increasing attention over the past years. These granules consist of RNA and a plethora of RNA-binding proteins. Mutations in RNA-binding proteins have been found in neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). By performing pulldown experiments and subsequent mass spectrometry on mouse brain lysates, we discovered that the de-ubiquitylating enzyme OTU domain-containing protein 4 (OTUD4) unexpectedly is part of a complex network of multiple RNA-binding proteins, including core stress granule factors, such as FMRP (also known as FMR1), SMN1, G3BP1 and TIA1. We show that OTUD4 binds RNA, and that several of its interactions with RNA-binding proteins are RNA dependent. OTUD4 is part of neuronal RNA transport granules in rat hippocampal neurons under physiological conditions, whereas upon cellular stress, OTUD4 is recruited to cytoplasmic stress granules. Knockdown of OTUD4 in HeLa cells resulted in defects in stress granule formation and led to apoptotic cell death. Together, we characterize OTUD4 as a new RNA-binding protein with a suggested function in regulation of translation.
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Affiliation(s)
- Richa Das
- Ubiquitin Signaling Group, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Lukas Schwintzer
- Ubiquitin Signaling Group, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Stanislav Vinopal
- Axon Growth and Regeneration Group, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Eva Aguado Roca
- Ubiquitin Signaling Group, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Marc Sylvester
- Institute of Biochemistry and Molecular Biology, Core Facility Mass Spectrometry, University of Bonn, Nussallee 11, 53115 Bonn, Germany
| | - Ana-Maria Oprisoreanu
- Institute of Neuropathology and Department of Epileptology, University of Bonn, Sigmund-Freud-Str. 25, 53127 Bonn, Germany
| | - Susanne Schoch
- Institute of Neuropathology and Department of Epileptology, University of Bonn, Sigmund-Freud-Str. 25, 53127 Bonn, Germany
| | - Frank Bradke
- Axon Growth and Regeneration Group, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Meike Broemer
- Ubiquitin Signaling Group, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
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3
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Schwintzer L, Aguado Roca E, Broemer M. TRIAD3/RNF216 E3 ligase specifically synthesises K63-linked ubiquitin chains and is inactivated by mutations associated with Gordon Holmes syndrome. Cell Death Discov 2019; 5:75. [PMID: 30886743 PMCID: PMC6411869 DOI: 10.1038/s41420-019-0158-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [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: 02/18/2019] [Accepted: 02/23/2019] [Indexed: 11/13/2022] Open
Abstract
TRIAD3/RNF216 is a ubiquitin ligase of the RING-in-between-RING family. Recent publications identified TRIAD3 mutations in patients with neurological diseases, including Gordon Holmes syndrome and Huntington-like disorder. To understand the functional relevance of these disease-associated mutations, we have tested the ubiquitin ligase activity of mutated TRIAD3 in vitro. Several of these point mutations completely abrogated TRIAD3’s catalytic activity. Using mass spectrometry, we identified new TRIAD3-interacting proteins/substrates from mouse brain lysate, which provide a new link between TRIAD3 and processes involving clathrin-mediated endocytosis. Strikingly, we found that TRIAD3 synthesises specifically lysine-63 (K63)-linked poly-ubiquitin chains in vitro, a chain type that usually plays a role in mediating signalling events rather than triggering proteasomal degradation. Therefore, this finding is of great importance to further understand TRIAD3’s cellular role and loss-of-function in disease.
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Affiliation(s)
- Lukas Schwintzer
- Ubiquitin Signaling Group, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Eva Aguado Roca
- Ubiquitin Signaling Group, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
| | - Meike Broemer
- Ubiquitin Signaling Group, German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127 Bonn, Germany
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4
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Schilling J, Broemer M, Atanassov I, Duernberger Y, Vorberg I, Dieterich C, Dagane A, Dittmar G, Wanker E, van Roon-Mom W, Winter J, Krauß S. Deregulated Splicing Is a Major Mechanism of RNA-Induced Toxicity in Huntington's Disease. J Mol Biol 2019; 431:1869-1877. [PMID: 30711541 DOI: 10.1016/j.jmb.2019.01.034] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [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: 10/24/2018] [Revised: 01/21/2019] [Accepted: 01/24/2019] [Indexed: 12/20/2022]
Abstract
Huntington's disease (HD) is caused by an expanded CAG repeat in the huntingtin (HTT) gene, translating into an elongated polyglutamine stretch. In addition to the neurotoxic mutant HTT protein, the mutant CAG repeat RNA can exert toxic functions by trapping RNA-binding proteins. While few examples of proteins that aberrantly bind to mutant HTT RNA and execute abnormal function in conjunction with the CAG repeat RNA have been described, an unbiased approach to identify the interactome of mutant HTT RNA is missing. Here, we describe the analysis of proteins that preferentially bind mutant HTT RNA using a mass spectrometry approach. We show that (I) the majority of proteins captured by mutant HTT RNA belong to the spliceosome pathway, (II) expression of mutant CAG repeat RNA induces mis-splicing in a HD cell model, (III) overexpression of one of the splice factors trapped by mutant HTT ameliorates the HD phenotype in a fly model and (VI) deregulated splicing occurs in human HD brain. Our data suggest that deregulated splicing is a prominent mechanism of RNA-induced toxicity in HD.
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Affiliation(s)
- Judith Schilling
- German Center for Neurodegenerative Diseases (DZNE), 53127, Bonn, North Rhine-Westphalia, Germany
| | - Meike Broemer
- German Center for Neurodegenerative Diseases (DZNE), 53127, Bonn, North Rhine-Westphalia, Germany
| | - Ilian Atanassov
- Max Planck Institute for Biology of Ageing, 50931 Cologne, North Rhine-Westphalia, Germany
| | - Yvonne Duernberger
- German Center for Neurodegenerative Diseases (DZNE), 53127, Bonn, North Rhine-Westphalia, Germany
| | - Ina Vorberg
- German Center for Neurodegenerative Diseases (DZNE), 53127, Bonn, North Rhine-Westphalia, Germany; Department of Neurology, Friedrich-Wilhelms-Universität Bonn, 53127 Bonn, North Rhine-Westphalia, Germany
| | - Christoph Dieterich
- Max Planck Institute for Biology of Ageing, 50931 Cologne, North Rhine-Westphalia, Germany
| | - Alina Dagane
- Max-Delbrück-Center for Molecular Medicine (MDC), 13092 Berlin, Germany
| | - Gunnar Dittmar
- Max-Delbrück-Center for Molecular Medicine (MDC), 13092 Berlin, Germany; Luxembourg Institute of Health, 1445 Strassen, Luxembourg
| | - Erich Wanker
- Max-Delbrück-Center for Molecular Medicine (MDC), 13092 Berlin, Germany
| | | | - Jennifer Winter
- Institute of Human Genetics, University Medical Center, Johannes Gutenberg University Mainz, 55131 Mainz, Rhineland-Palatinate, Germany
| | - Sybille Krauß
- German Center for Neurodegenerative Diseases (DZNE), 53127, Bonn, North Rhine-Westphalia, Germany.
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Aalto AL, Mohan AK, Schwintzer L, Kupka S, Kietz C, Walczak H, Broemer M, Meinander A. M1-linked ubiquitination by LUBEL is required for inflammatory responses to oral infection in Drosophila. Cell Death Differ 2018; 26:860-876. [PMID: 30026495 PMCID: PMC6462001 DOI: 10.1038/s41418-018-0164-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [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: 01/24/2018] [Revised: 06/20/2018] [Accepted: 07/02/2018] [Indexed: 01/04/2023] Open
Abstract
Post-translational modifications such as ubiquitination play a key role in regulation of inflammatory nuclear factor-κB (NF-κB) signalling. The Drosophila IκB kinase γ (IKKγ) Kenny is a central regulator of the Drosophila Imd pathway responsible for activation of the NF-κB Relish. We found the Drosophila E3 ligase and HOIL-1L interacting protein (HOIP) orthologue linear ubiquitin E3 ligase (LUBEL) to catalyse formation of M1-linked linear ubiquitin (M1-Ub) chains in flies in a signal-dependent manner upon bacterial infection. Upon activation of the Imd pathway, LUBEL modifies Kenny with M1-Ub chains. Interestingly, the LUBEL-mediated M1-Ub chains seem to be targeted both directly to Kenny and to K63-linked ubiquitin chains conjugated to Kenny by DIAP2. This suggests that DIAP2 and LUBEL work together to promote Kenny-mediated activation of Relish. We found LUBEL-mediated M1-Ub chain formation to be required for flies to survive oral infection with Gram-negative bacteria, for activation of Relish-mediated expression of antimicrobial peptide genes and for pathogen clearance during oral infection. Interestingly, LUBEL is not required for mounting an immune response against systemic infection, as Relish-mediated antimicrobial peptide genes can be expressed in the absence of LUBEL during septic injury. Finally, transgenic induction of LUBEL-mediated M1-Ub drives expression of antimicrobial peptide genes and hyperplasia in the midgut in the absence of infection. This suggests that M1-Ub chains are important for Imd signalling and immune responses in the intestinal epithelia, and that enhanced M1-Ub chain formation is able to drive chronic intestinal inflammation in flies.
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Affiliation(s)
- Anna L Aalto
- Department of Cell Biology, Faculty of Science and Engineering, BioCity, Åbo Akademi University, 20520, Turku, Finland
| | - Aravind K Mohan
- Department of Cell Biology, Faculty of Science and Engineering, BioCity, Åbo Akademi University, 20520, Turku, Finland
| | - Lukas Schwintzer
- German Center for Neurodegenerative Diseases (DZNE), 53127, Bonn, Germany
| | - Sebastian Kupka
- Centre for Cell Death, Cancer and Inflammation (CCCI), UCL Cancer Institute, London, WC1E 6BT, UK
| | - Christa Kietz
- Department of Cell Biology, Faculty of Science and Engineering, BioCity, Åbo Akademi University, 20520, Turku, Finland
| | - Henning Walczak
- Centre for Cell Death, Cancer and Inflammation (CCCI), UCL Cancer Institute, London, WC1E 6BT, UK
| | - Meike Broemer
- German Center for Neurodegenerative Diseases (DZNE), 53127, Bonn, Germany
| | - Annika Meinander
- Department of Cell Biology, Faculty of Science and Engineering, BioCity, Åbo Akademi University, 20520, Turku, Finland.
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6
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Wakabayashi S, Sawamura N, Voelzmann A, Broemer M, Asahi T, Hoch M. Ohgata, the Single Drosophila Ortholog of Human Cereblon, Regulates Insulin Signaling-dependent Organismic Growth. J Biol Chem 2016; 291:25120-25132. [PMID: 27702999 DOI: 10.1074/jbc.m116.757823] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [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: 09/09/2016] [Indexed: 11/06/2022] Open
Abstract
Cereblon (CRBN) is a substrate receptor of the E3 ubiquitin ligase complex that is highly conserved in animals and plants. CRBN proteins have been implicated in various biological processes such as development, metabolism, learning, and memory formation, and their impairment has been linked to autosomal recessive non-syndromic intellectual disability and cancer. Furthermore, human CRBN was identified as the primary target of thalidomide teratogenicity. Data on functional analysis of CRBN family members in vivo, however, are still scarce. Here we identify Ohgata (OHGT), the Drosophila ortholog of CRBN, as a regulator of insulin signaling-mediated growth. Using ohgt mutants that we generated by targeted mutagenesis, we show that its loss results in increased body weight and organ size without changes of the body proportions. We demonstrate that ohgt knockdown in the fat body, an organ analogous to mammalian liver and adipose tissue, phenocopies the growth phenotypes. We further show that overgrowth is due to an elevation of insulin signaling in ohgt mutants and to the down-regulation of inhibitory cofactors of circulating Drosophila insulin-like peptides (DILPs), named acid-labile subunit and imaginal morphogenesis protein-late 2. The two inhibitory proteins were previously shown to be components of a heterotrimeric complex with growth-promoting DILP2 and DILP5. Our study reveals OHGT as a novel regulator of insulin-dependent organismic growth in Drosophila.
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Affiliation(s)
- Satoru Wakabayashi
- From the Faculty of Science and Engineering, Waseda University, TWIns, 2-2 Wakamatsu, Shinjuku, Tokyo 162-8480, Japan
| | - Naoya Sawamura
- From the Faculty of Science and Engineering, Waseda University, TWIns, 2-2 Wakamatsu, Shinjuku, Tokyo 162-8480, Japan, .,the Research Organization for Nano-life Innovation, Waseda University, Shinjuku, Tokyo 162-0041, Japan
| | - André Voelzmann
- the Faculty of Biology, Medicine and Health, The University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, United Kingdom
| | - Meike Broemer
- the German Center for Neurodegenerative Diseases (DZNE), c/o Life and Medical Sciences (LIMES) Institute, Carl-Troll-Strasse 31, 53115 Bonn, Germany, and
| | - Toru Asahi
- From the Faculty of Science and Engineering, Waseda University, TWIns, 2-2 Wakamatsu, Shinjuku, Tokyo 162-8480, Japan, .,the Research Organization for Nano-life Innovation, Waseda University, Shinjuku, Tokyo 162-0041, Japan
| | - Michael Hoch
- Program Unit Development, Genetics and Molecular Physiology, Laboratory for Molecular Developmental Biology, LIMES Institute, University of Bonn, Carl-Troll-Strasse 31, 53115 Bonn, Germany
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7
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Melzer J, Broemer M. Nerve-racking - apoptotic and non-apoptotic roles of caspases in the nervous system of Drosophila. Eur J Neurosci 2016; 44:1683-90. [PMID: 26900934 DOI: 10.1111/ejn.13213] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [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: 01/13/2016] [Revised: 02/02/2016] [Accepted: 02/15/2016] [Indexed: 12/28/2022]
Abstract
Studies using Drosophila as a model system have contributed enormously to our knowledge of caspase function and regulation. Caspases are best known as central executioners of apoptosis but also control essential physiological processes in a non-apoptotic manner. The Drosophila genome codes for seven caspases and in this review we provide an overview of current knowledge about caspase function in the nervous system. Caspases regulate neuronal death at all developmental stages and in various neuronal populations. In contrast, non-apoptotic roles are less well understood. The development of new genetically encoded sensors for caspase activity provides unprecedented opportunities to study caspase function in the nervous system in more detail. In light of these new tools we discuss the potential of Drosophila as a model to discover new apoptotic and non-apoptotic neuronal roles of caspases.
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Affiliation(s)
- Juliane Melzer
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Meike Broemer
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
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8
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Abstract
Understanding function and specificity of de-ubiquitylating enzymes (DUBs) is a major goal of current research, since DUBs are key regulators of ubiquitylation events and have been shown to be mutated in human diseases. Most DUBs are cysteine proteases, relying on a catalytic triad of cysteine, histidine and aspartate to cleave the isopeptide bond between two ubiquitin units in a poly-ubiquitin chain. We have discovered that the two Drosophila melanogaster homologues of human OTUD4, CG3251 and Otu, contain a serine instead of a cysteine in the catalytic OTU (ovarian tumor) domain. DUBs that are serine proteases instead of cysteine- or metallo-proteases have not been described. In line with this, neither CG3251 nor Otu protein were active to cleave ubiquitin chains. Re-introduction of a cysteine in the catalytic center did not render the enzymes active, indicating that further critical features for ubiquitin binding or cleavage have been lost in these proteins. Sequence analysis of OTUD4 homologues from various other species showed that within this OTU subfamily, loss of the catalytic cysteine has occurred frequently in presumably independent events, as well as gene duplications or triplications, suggesting DUB-independent functions of OTUD4 proteins. Using an in vivo RNAi approach, we show that CG3251 might function in the regulation of Inhibitor of Apoptosis (IAP)-antagonist-induced apoptosis, presumably in a DUB-independent manner.
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Affiliation(s)
- Marcell Louis
- German Center for Neurodegenerative Diseases (DZNE), Bonn, c/o LiMeS, Carl-Troll-Str. 31, 53115, Bonn, Germany
| | - Kay Hofmann
- University of Cologne, Institute for Genetics, Zülpicher Str. 47a, 50674, Cologne, Germany
| | - Meike Broemer
- German Center for Neurodegenerative Diseases (DZNE), Bonn, c/o LiMeS, Carl-Troll-Str. 31, 53115, Bonn, Germany
- * E-mail:
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9
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Tenev T, Bianchi K, Darding M, Broemer M, Langlais C, Wallberg F, Zachariou A, Lopez J, MacFarlane M, Cain K, Meier P. The Ripoptosome, a Signaling Platform that Assembles in Response to Genotoxic Stress and Loss of IAPs. Mol Cell 2011. [DOI: 10.1016/j.molcel.2011.08.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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10
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Tenev T, Bianchi K, Darding M, Broemer M, Langlais C, Wallberg F, Zachariou A, Lopez J, MacFarlane M, Cain K, Meier P. The Ripoptosome, a signaling platform that assembles in response to genotoxic stress and loss of IAPs. Mol Cell 2011; 43:432-48. [PMID: 21737329 DOI: 10.1016/j.molcel.2011.06.006] [Citation(s) in RCA: 718] [Impact Index Per Article: 55.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Revised: 05/16/2011] [Accepted: 06/08/2011] [Indexed: 10/18/2022]
Abstract
A better understanding of the mechanisms through which anticancer drugs exert their effects is essential to improve combination therapies. While studying how genotoxic stress kills cancer cells, we discovered a large ∼2MDa cell death-inducing platform, referred to as "Ripoptosome." It contains the core components RIP1, FADD, and caspase-8, and assembles in response to genotoxic stress-induced depletion of XIAP, cIAP1 and cIAP2. Importantly, it forms independently of TNF, CD95L/FASL, TRAIL, death-receptors, and mitochondrial pathways. It also forms upon Smac-mimetic (SM) treatment without involvement of autocrine TNF. Ripoptosome assembly requires RIP1's kinase activity and can stimulate caspase-8-mediated apoptosis as well as caspase-independent necrosis. It is negatively regulated by FLIP, cIAP1, cIAP2, and XIAP. Mechanistically, IAPs target components of this complex for ubiquitylation and inactivation. Moreover, we find that etoposide-stimulated Ripoptosome formation converts proinflammatory cytokines into prodeath signals. Together, our observations shed new light on fundamental mechanisms by which chemotherapeutics may kill cancer cells.
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Affiliation(s)
- Tencho Tenev
- The Breakthrough Toby Robins Breast Cancer Research Centre, Institute of Cancer Research, London, UK.
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11
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Lopez J, John S, Tenev T, Rautureau G, Hinds M, Francalanci F, Wilson R, Broemer M, Santoro M, Day C, Meier P. CARD-Mediated Autoinhibition of cIAP1's E3 Ligase Activity Suppresses Cell Proliferation and Migration. Mol Cell 2011; 42:569-83. [DOI: 10.1016/j.molcel.2011.04.008] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Revised: 04/04/2011] [Accepted: 04/18/2011] [Indexed: 01/18/2023]
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12
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Rehm A, Anagnostopoulos I, Gerlach K, Broemer M, Scheidereit C, Jöhrens K, Hübler M, Hetzer R, Stein H, Lipp M, Dörken B, Höpken UE. Identification of a chemokine receptor profile characteristic for mediastinal large B-cell lymphoma. Int J Cancer 2009; 125:2367-74. [PMID: 19536742 DOI: 10.1002/ijc.24652] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Mediastinal large B-cell lymphomas (MLBCLs) are considered as a subtype of diffuse large B-cell lymphoma; however, they exhibit completely different patterns of dissemination. Since they share a number of surface markers with thymic B cells, a close relationship was assumed. MLBCLs arise extranodally within the anterior mediastinum and have a low propensity to metastasize. To address the preferential positioning of MLBCL, we focused on homeostatic chemokines involved in B-cell compartmental homing in secondary lymphoid organs, which are also capable of shaping lymphoid niches in ectopic sites. Here, we applied immunohistochemistry to assess chemokine receptor and ligand expression in situ. Flow cytometry was used to identify the chemokine receptor profile on an MLBCL-derived cell line, Karpas1106 and on thymic B cells. Migration assays were performed to examine functionality of chemokine receptors. Electrophoretic mobility shift assay was applied to score for NF-kappaB activity. Using immunohistochemistry, we obtained an unexpectedly low-expression frequency for the chemokine receptors CXCR5 and CCR7 in primary lesions. Although the mature B-cell marker CCR6 was absent in most cases, the lineage aberrant marker CCR9 emerged in the majority of MLBCL cases. Given the role of NF-kappaB in the transcriptional activation of CCR7, we identified the involvement of the noncanonical activation pathway in MLBCLs. MLBCLs exhibit a diagnostic chemokine receptor profile that is instrumental in the discrimination from diffuse large B-cell lymphoma not otherwise specified and classical Hodgkin lymphoma. Furthermore, we suggest that low-abundance expression of CCR7 and CXCR5 may hinder lymphoma cells from nodal dissemination.
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Affiliation(s)
- Armin Rehm
- Max-Delbrück-Center for Molecular Medicine, Berlin, Germany.
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13
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Abstract
Ubiquitin is a protein modifier that is conjugated to target proteins either as a single moiety or as polyubiquitin chains. Over the past several years, an increasing number of ubiquitin ligases and ubiquitin-deconjugating enzymes have been identified; these modulate cell survival by degradative and non-degradative means. Mutations that affect ubiquitin-mediated signalling are tightly linked to various human pathologies including tumorigenesis. Unravelling how the ubiquitin-signal is conjugated, edited and 'read' is crucial to understanding cellular processes such as endocytic trafficking, NF-kappaB signalling, gene expression, DNA repair and apoptosis. In this review, we summarize recent advances that start to elucidate how the ubiquitin message is used as a versatile tool to regulate apoptosis, for example in the conjugation of ubiquitin to caspases. This results in steric interference with substrate entry and allosteric conformational impairment of the catalytic pocket of the caspase.
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Affiliation(s)
- Meike Broemer
- The Breakthrough Toby Robins Breast Cancer Research Centre, Institute of Cancer Research, Mary-Jean Mitchell Green Building, Chester Beatty Laboratories, Fulham Road, London SW3 6JB, UK.
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14
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Ditzel M, Broemer M, Tenev T, Bolduc C, Lee TV, Rigbolt KTG, Elliott R, Zvelebil M, Blagoev B, Bergmann A, Meier P. Inactivation of effector caspases through nondegradative polyubiquitylation. Mol Cell 2009; 32:540-53. [PMID: 19026784 DOI: 10.1016/j.molcel.2008.09.025] [Citation(s) in RCA: 102] [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] [Received: 04/23/2008] [Revised: 08/14/2008] [Accepted: 09/26/2008] [Indexed: 11/26/2022]
Abstract
Ubiquitin-mediated inactivation of caspases has long been postulated to contribute to the regulation of apoptosis. However, detailed mechanisms and functional consequences of caspase ubiquitylation have not been demonstrated. Here we show that the Drosophila Inhibitor of Apoptosis 1, DIAP1, blocks effector caspases by targeting them for polyubiquitylation and nonproteasomal inactivation. We demonstrate that the conjugation of ubiquitin to drICE suppresses its catalytic potential in cleaving caspase substrates. Our data suggest that ubiquitin conjugation sterically interferes with substrate entry and reduces the caspase's proteolytic velocity. Disruption of drICE ubiquitylation, either by mutation of DIAP1's E3 activity or drICE's ubiquitin-acceptor lysines, abrogates DIAP1's ability to neutralize drICE and suppress apoptosis in vivo. We also show that DIAP1 rests in an "inactive" conformation that requires caspase-mediated cleavage to subsequently ubiquitylate caspases. Taken together, our findings demonstrate that effector caspases regulate their own inhibition through a negative feedback mechanism involving DIAP1 "activation" and nondegradative polyubiquitylation.
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Affiliation(s)
- Mark Ditzel
- The Breakthrough Toby Robins Breast Cancer Research Centre, Institute of Cancer Research, Mary-Jean Mitchell Green Building, Chester Beatty Laboratories, Fulham Road, London SW3 6JB, UK.
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15
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Hinz M, Broemer M, Arslan SC, Otto A, Mueller EC, Dettmer R, Scheidereit C. Signal Responsiveness of IκB Kinases Is Determined by Cdc37-assisted Transient Interaction with Hsp90. J Biol Chem 2007; 282:32311-9. [PMID: 17728246 DOI: 10.1074/jbc.m705785200] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The IkappaB kinase (IKK) holocomplex, containing the kinases IKKalpha, IKKbeta, and the scaffold NEMO (NF-kappaB essential modifier), mediates activation of NF-kappaB by numerous physiological stimuli. Heat shock protein 90 (Hsp90) and the co-chaperone Cdc37 have been indicated as additional subunits, but their specific functions in signal transduction are indistinct. Using an RNA interference approach, we demonstrate that Cdc37 recruits Hsp90 to the IKK complex in a transitory manner, preferentially via IKKalpha. Binding is conferred by N-terminal as well as C-terminal residues of Cdc37. Cdc37 is essential for the maturation of de novo synthesized IKKs into enzymatically competent kinases but not for assembly of an IKK holocomplex. Mature IKKs, T-loop-phosphorylated after stimulation either by receptor-mediated signaling or upon DNA damage, further require Hsp90-Cdc37 to generate an activated state. Thus, the present data denote Hsp90-Cdc37 as a transiently acting essential regulatory component of IKK signaling.
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Affiliation(s)
- Michael Hinz
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
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16
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Broemer M, Krappmann D, Scheidereit C. Requirement of Hsp90 activity for IkappaB kinase (IKK) biosynthesis and for constitutive and inducible IKK and NF-kappaB activation. Oncogene 2004; 23:5378-86. [PMID: 15077173 DOI: 10.1038/sj.onc.1207705] [Citation(s) in RCA: 181] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The molecular chaperone Hsp90 affects the function and fate of a number of signaling molecules. We have investigated the Hsp90 requirement for constitutive and inducible activity of the IkappaB kinase (IKK) complex and of NF-kappaB. Inhibition by the Hsp90 ATPase inhibitors, geldanamycin (GA) and radicicol (RC), revealed that Hsp90 controls IKKs at two levels, inducibility of enzymatic activity and biogenesis, which can be discriminated by short- and long-time GA incubation, respectively. Short-time inhibition of Hsp90 resulted in impaired IKK kinase activation by TNFalpha, IL-1beta or phorbolester PMA. Furthermore, GA inhibited constitutive activation of IKK and NF-kappaB in Hodgkin's lymphoma cells. Hsp90 function was also required for trans- and autophosphorylation of transfected IKKbeta. GA exposure for several hours resulted in a downmodulation of IKK complex alpha, beta and gamma subunits to various extent. Proteasome inhibition interfered with GA mediated IKK depletion and Hsp90 inhibition induced polyubiquitination of IKKalpha and beta during protein synthesis. In fact, GA blocked biogenesis of IKKalpha and IKKbeta but did not interfere with post-translational turnover. Together, these results define a dual requirement for Hsp90 as a regulator of NF-kappaB signaling by its general involvement in IKK activation and by its role in IKK homeostasis.
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Affiliation(s)
- Meike Broemer
- Max-Delbrück-Center for Molecular Medicine, Robert-Rössle Str. 10, 13092 Berlin, Germany
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Holtmann H, Enninga J, Kalble S, Thiefes A, Dorrie A, Broemer M, Winzen R, Wilhelm A, Ninomiya-Tsuji J, Matsumoto K, Resch K, Kracht M. The MAPK kinase kinase TAK1 plays a central role in coupling the interleukin-1 receptor to both transcriptional and RNA-targeted mechanisms of gene regulation. J Biol Chem 2001; 276:3508-16. [PMID: 11050078 DOI: 10.1074/jbc.m004376200] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mechanisms of fulminant gene induction during an inflammatory response were investigated using expression of the chemoattractant cytokine interleukin-8 (IL-8) as a model. Recently we found that coordinate activation of NF-kappaB and c-Jun N-terminal protein kinase (JNK) is required for strong IL-8 transcription, whereas the p38 MAP kinase (MAPK) pathway stabilizes the IL-8 mRNA. It is unclear how these pathways are coupled to the receptor for IL-1, an important physiological inducer of IL-8. Expression of the MAP kinase kinase kinase (MAPKKK) TAK1 together with its coactivator TAB1 in HeLa cells activated all three pathways and was sufficient to induce IL-8 formation, NF-kappaB + JNK2-mediated transcription from a minimal IL-8 promoter, and p38 MAPK-mediated stabilization of a reporter mRNA containing IL-8-derived regulatory mRNA sequences. Expression of a kinase-inactive mutant of TAK1 largely blocked IL-1-induced transcription and mRNA stabilization, as well as formation of endogenous IL-8. Truncated TAB1, lacking the TAK1 binding domain, or a TAK1-derived peptide containing a TAK1 autoinhibitory domain were also efficient in inhibition. These data indicate that the previously described three-pathway model of IL-8 induction is operative in response to a physiological stimulus, IL-1, and that the MAPKKK TAK1 couples the IL-1 receptor to both transcriptional and RNA-targeted mechanisms mediated by the three pathways.
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Affiliation(s)
- H Holtmann
- Institute of Pharmacology, Medical School Hannover, Carl-Neuberg-Strasse 1, D-30625 Hannover, Germany
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