1
|
Aalto AL, Luukkonen V, Meinander A. Ubiquitin signalling in Drosophila innate immune responses. FEBS J 2023. [PMID: 38069549 DOI: 10.1111/febs.17028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 11/24/2023] [Accepted: 12/07/2023] [Indexed: 12/19/2023]
Abstract
Cells respond to invading pathogens and danger signals from the environment by adapting gene expression to meet the need for protective effector molecules. While this innate immune response is required for the cell and the organism to recover, excess immune activation may lead to loss of homeostasis, thereby promoting chronic inflammation and cancer progression. The molecular basis of innate immune defence is comprised of factors promoting survival and proliferation, such as cytokines, antimicrobial peptides and anti-apoptotic proteins. As the molecular mechanisms regulating innate immune responses are conserved through evolution, the fruit fly Drosophila melanogaster serves as a convenient, affordable and ethical model organism to enhance understanding of immune signalling. Fly immunity against bacterial infection is built up by both cellular and humoral responses, where the latter is regulated by the Imd and Toll pathways activating NF-κB transcription factors Relish, Dorsal and Dif, as well as JNK activation and JAK/STAT signalling. As in mammals, the Drosophila innate immune signalling pathways are characterised by ubiquitination of signalling molecules followed by ubiquitin receptors binding to the ubiquitin chains, as well as by rapid changes in protein levels by ubiquitin-mediated targeted proteasomal and lysosomal degradation. In this review, we summarise the molecular signalling pathways regulating immune responses to pathogen infection in Drosophila, with a focus on ubiquitin-dependent control of innate immunity and inflammatory signalling.
Collapse
Affiliation(s)
- Anna L Aalto
- Faculty of Science and Engineering, Cell Biology, Åbo Akademi University, Turku, Finland
- InFLAMES Research Flagship, Åbo Akademi University, Turku, Finland
| | - Veera Luukkonen
- Faculty of Science and Engineering, Cell Biology, Åbo Akademi University, Turku, Finland
| | - Annika Meinander
- Faculty of Science and Engineering, Cell Biology, Åbo Akademi University, Turku, Finland
- InFLAMES Research Flagship, Åbo Akademi University, Turku, Finland
| |
Collapse
|
2
|
Zhang J, Ning J, Fu W, Shi Y, Zhang J, Ding S. CMTM3 protects the gastric epithelial cells from apoptosis and promotes IL-8 by stabilizing NEMO during Helicobacter pylori infection. Gut Pathog 2023; 15:6. [PMID: 36782312 PMCID: PMC9924195 DOI: 10.1186/s13099-023-00533-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 02/06/2023] [Indexed: 02/15/2023] Open
Abstract
BACKGROUND CKLF-like MARVEL transmembrane domain containing 3 (CMTM3) plays an important role in cancer development. Although Helicobacter pylori (H. pylori) infection is a main cause of gastric cancer, the function of CMTM3 during H. pylori infection remains unclear. CMTM3 expression levels in tissues from H. pylori-infected patients and cells co-cultured with H. pylori were analyzed. qRT-PCR and ELISA were used to investigate the effects of CMTM3 on interleukin 8 (IL-8) expression. Annexin V/propidium iodide staining was performed to evaluate the function of CMTM3 in the apoptosis of gastric epithelial cells. Proteomic analysis was performed to explore the underlying mechanism of CMTM3 during H. pylori infection. The interaction between CMTM3 and NEMO was determined via co-immunoprecipitation, HA-ubiquitin pull-down assay, and immunofluorescence. RESULTS H. pylori induced a significant increase in CMTM3 expression. CMTM3 inhibited gastric mucosal epithelial cells from apoptosis and increased the expression level of IL-8 during H. pylori infection. KEGG pathway enrichment analysis revealed that differentially expressed proteins were involved in epithelial cell signaling in H. pylori infection. CMTM3 directly interacted with NEMO, which promoted protein stabilization by down-regulation of its ubiquitylation. CONCLUSIONS CMTM3 reduces apoptosis and promotes IL-8 expression in the gastric epithelial cells by stabilizing NEMO during H. pylori infection. These findings characterize a new role for CMTM3 in host-pathogen interactions and provide novel insight into the molecular regulation of NEMO.
Collapse
Affiliation(s)
- Jing Zhang
- grid.411642.40000 0004 0605 3760Department of Gastroenterology, Peking University Third Hospital, 49 Huayuan North Road, Haidian District, Beijing, 100191 People’s Republic of China
| | - Jing Ning
- grid.411642.40000 0004 0605 3760Department of Gastroenterology, Peking University Third Hospital, 49 Huayuan North Road, Haidian District, Beijing, 100191 People’s Republic of China
| | - Weiwei Fu
- grid.411642.40000 0004 0605 3760Department of Gastroenterology, Peking University Third Hospital, 49 Huayuan North Road, Haidian District, Beijing, 100191 People’s Republic of China
| | - Yanyan Shi
- grid.411642.40000 0004 0605 3760Research Center of Clinical Epidemiology, Peking University Third Hospital, 49 Huayuan North Road, Haidian District, Beijing, 100191 People’s Republic of China
| | - Jing Zhang
- grid.411642.40000 0004 0605 3760Department of Gastroenterology, Peking University Third Hospital, 49 Huayuan North Road, Haidian District, Beijing, 100191 People’s Republic of China
| | - Shigang Ding
- Department of Gastroenterology, Peking University Third Hospital, 49 Huayuan North Road, Haidian District, Beijing, 100191, People's Republic of China.
| |
Collapse
|
3
|
Wang HY, Zhao HM, Wang Y, Liu Y, Lu XY, Liu XK, Chen F, Ge W, Zuo ZY, Liu DY. Sishen Wan ® Ameliorated Trinitrobenzene-Sulfonic-Acid-Induced Chronic Colitis via NEMO/NLK Signaling Pathway. Front Pharmacol 2019; 10:170. [PMID: 30894816 PMCID: PMC6414459 DOI: 10.3389/fphar.2019.00170] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 02/11/2019] [Indexed: 01/22/2023] Open
Abstract
The nuclear factor (NF)-κB signaling pathway plays an important role in the initialization and development phase of inflammatory injuries, including inflammatory bowel disease (IBD). Sishen Wan (SSW) is a classic Chinese patent medicine listed in the Chinese Pharmacopoeia, which is usually used to treat chronic colitis; however, it is unclear whether SSW can treat IBD via the NF-κB signaling pathway. In the present study, the therapeutic effect of SSW was demonstrated by the decreased index of colonic weight, macroscopic and microscopic score, and pathological observation in chronic colitis induced by trinitrobenzene sulfonic acid. In colonic mucosa of rats with chronic colitis, SSW reduced the levels of calprotectin and eliminated oxidative lesions; downregulated expression of interferon-γ, interleukin (IL)-1β and IL-17; increased expression of IL-4; and suppressed expression of NF-κB p65, and NF-κB essential modulator (NEMO)-like kinase (NLK). Furthermore, SSW inhibited ubiquitinated NEMO, ubiquitin-activated enzyme, and E2i activation, and phosphorylation of downstream proteins (cylindromatosis protein, transforming growth factor-β-activated kinase and P38). These results show that the therapeutic effects of SSW in chronic colitis were mediated by inhibiting the NEMO/NLK signaling pathway to suppress NF-κB activation.
Collapse
Affiliation(s)
- Hai-Yan Wang
- Party and School Office, Jiangxi University of Traditional Chinese Medicine, Nanchang, China
| | - Hai-Mei Zhao
- School of Basic Medical Sciences, Jiangxi University of Traditional Chinese Medicine, Nanchang, China
| | - Yao Wang
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Heilongjiang University of Chinese Medicine, Harbin, China
| | - Yi Liu
- Department of Postgraduate, Jiangxi University of Traditional Chinese Medicine, Nanchang, China
| | - Xiu-Yun Lu
- Science and Technology College, Jiangxi University of Traditional Chinese Medicine, Nanchang, China
| | - Xue-Ke Liu
- Department of Postgraduate, Jiangxi University of Traditional Chinese Medicine, Nanchang, China
| | - Fang Chen
- Department of Postgraduate, Jiangxi University of Traditional Chinese Medicine, Nanchang, China
| | - Wei Ge
- Affiliated Hospital of Jiangxi University of Traditional Chinese Medicine, Nanchang, China
| | - Zheng-Yun Zuo
- Affiliated Hospital of Jiangxi University of Traditional Chinese Medicine, Nanchang, China
| | - Duan-Yong Liu
- Science and Technology College, Jiangxi University of Traditional Chinese Medicine, Nanchang, China.,Key Laboratory of Pharmacology of Traditional Chinese Medicine in Jiangxi, Nanchang, China
| |
Collapse
|
4
|
Cyclophilin J limits inflammation through the blockage of ubiquitin chain sensing. Nat Commun 2018; 9:4381. [PMID: 30348973 PMCID: PMC6197184 DOI: 10.1038/s41467-018-06756-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 09/26/2018] [Indexed: 01/16/2023] Open
Abstract
Maintaining innate immune homeostasis is important for individual health. Npl4 zinc finger (NZF) domain-mediated ubiquitin chain sensing is reported to function in the nuclear factor-kappa B (NF-κB) signal pathway, but the regulatory mechanism remains elusive. Here we show that cyclophilin J (CYPJ), a member of the peptidylprolyl isomerase family, is induced by inflammation. CYPJ interacts with the NZF domain of transform growth factor-β activated kinase 1 binding protein 2 and 3 as well as components of the linear ubiquitin chain assembly complex to block the binding of ubiquitin-chain and negatively regulates NF-κB signaling. Mice with Cypj deficiency are susceptible to lipopolysaccharide and heat-killed Listeria monocytogenes-induced sepsis and dextran sulfate sodium-induced colitis. These findings identify CYPJ as a negative feedback regulator of the NF-κB signaling pathway, and provide insights for understanding the homeostasis of innate immunity.
Collapse
|
5
|
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] [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.
Collapse
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.
| |
Collapse
|
6
|
Kim EK, Choi EJ. SMN1 functions as a novel inhibitor for TRAF6-mediated NF-κB signaling. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:760-770. [DOI: 10.1016/j.bbamcr.2017.02.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 02/10/2017] [Accepted: 02/14/2017] [Indexed: 12/30/2022]
|
7
|
Intracellular Mono-ADP-Ribosylation in Signaling and Disease. Cells 2015; 4:569-95. [PMID: 26426055 PMCID: PMC4695847 DOI: 10.3390/cells4040569] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 09/17/2015] [Accepted: 09/21/2015] [Indexed: 12/20/2022] Open
Abstract
A key process in the regulation of protein activities and thus cellular signaling pathways is the modification of proteins by post-translational mechanisms. Knowledge about the enzymes (writers and erasers) that attach and remove post-translational modifications, the targets that are modified and the functional consequences elicited by specific modifications, is crucial for understanding cell biological processes. Moreover detailed knowledge about these mechanisms and pathways helps to elucidate the molecular causes of various diseases and in defining potential targets for therapeutic approaches. Intracellular adenosine diphosphate (ADP)-ribosylation refers to the nicotinamide adenine dinucleotide (NAD+)-dependent modification of proteins with ADP-ribose and is catalyzed by enzymes of the ARTD (ADP-ribosyltransferase diphtheria toxin like, also known as PARP) family as well as some members of the Sirtuin family. Poly-ADP-ribosylation is relatively well understood with inhibitors being used as anti-cancer agents. However, the majority of ARTD enzymes and the ADP-ribosylating Sirtuins are restricted to catalyzing mono-ADP-ribosylation. Although writers, readers and erasers of intracellular mono-ADP-ribosylation have been identified only recently, it is becoming more and more evident that this reversible post-translational modification is capable of modulating key intracellular processes and signaling pathways. These include signal transduction mechanisms, stress pathways associated with the endoplasmic reticulum and stress granules, and chromatin-associated processes such as transcription and DNA repair. We hypothesize that mono-ADP-ribosylation controls, through these different pathways, the development of cancer and infectious diseases.
Collapse
|
8
|
Senegas A, Gautheron J, Maurin AGD, Courtois G. IKK-related genetic diseases: probing NF-κB functions in humans and other matters. Cell Mol Life Sci 2015; 72:1275-87. [PMID: 25432706 PMCID: PMC11113297 DOI: 10.1007/s00018-014-1793-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Revised: 11/04/2014] [Accepted: 11/20/2014] [Indexed: 12/28/2022]
Abstract
The transcription factor NF-κB plays a key role in numerous physiological processes such as inflammation, immunity, cell proliferation or control of cell death. Its activation is tightly controlled by a kinase complex, IκB kinase (IKK), composed of three core proteins: IKK1/IKKα, IKK2/IKKβ and NEMO/IKKγ. The first two are structurally related kinases whereas the third one is a regulatory subunit exhibiting affinity for upstream activators modified by polyubiquitin chains. Over the years, several inherited diseases caused by mutations of each of the three subunits of IKK have been identified in humans together with diseases caused by mutations of several of its substrates. They are associated with very specific and complex phenotypes involving a broad range of abnormalities such as impaired innate and acquired immune response, perturbed skin development and defects of the central nervous system. Here, we summarize the diverse clinical, cellular and molecular manifestations of IKK-related genetic diseases and show that studying patient-related mutations affecting the IKK subunits and some of their substrates offers the opportunity to understand the various functions of NF-κB in humans, complementing studies performed with mouse models. This analysis also provides glimpses about putative functions of IKK subunits that may be NF-κB-independent.
Collapse
Affiliation(s)
- Anna Senegas
- INSERM U1038, iRTSV, CEA Grenoble, Grenoble, France
- Université Grenoble Alpes, Grenoble, France
| | - Jérémie Gautheron
- Department of Gastroenterology, University Hospital RWTH Aachen, Aachen, Germany
| | - Alice Gentil Dit Maurin
- INSERM U1038, iRTSV, CEA Grenoble, Grenoble, France
- Université Grenoble Alpes, Grenoble, France
| | - Gilles Courtois
- INSERM U1038, iRTSV, CEA Grenoble, Grenoble, France
- Université Grenoble Alpes, Grenoble, France
| |
Collapse
|
9
|
Zhou L, Yeo AT, Ballarano C, Weber U, Allen KN, Gilmore TD, Whitty A. Disulfide-mediated stabilization of the IκB kinase binding domain of NF-κB essential modulator (NEMO). Biochemistry 2014; 53:7929-44. [PMID: 25400026 PMCID: PMC4278678 DOI: 10.1021/bi500920n] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
![]()
Human NEMO (NF-κB
essential modulator) is a 419 residue scaffolding
protein that, together with catalytic subunits IKKα and IKKβ,
forms the IκB kinase (IKK) complex, a key regulator of NF-κB
pathway signaling. NEMO is an elongated homodimer comprising mostly
α-helix. It has been shown that a NEMO fragment spanning residues
44–111, which contains the IKKα/β binding site,
is structurally disordered in the absence of bound IKKβ. Herein
we show that enforcing dimerization of NEMO1–120 or NEMO44–111 constructs through introduction
of one or two interchain disulfide bonds, through oxidation of the
native Cys54 residue and/or at position 107 through a Leu107Cys mutation,
induces a stable α-helical coiled-coil structure that is preorganized
to bind IKKβ with high affinity. Chemical and thermal denaturation
studies showed that, in the context of a covalent dimer, the ordered
structure was stabilized relative to the denatured state by up to
3 kcal/mol. A full-length NEMO-L107C protein formed covalent dimers
upon treatment of mammalian cells with H2O2.
Furthermore, NEMO-L107C bound endogenous IKKβ in A293T cells,
reconstituted TNF-induced NF-κB signaling in NEMO-deficient
cells, and interacted with TRAF6. Our results indicate that the IKKβ
binding domain of NEMO possesses an ordered structure in the unbound
state, provided that it is constrained within a dimer as is the case
in the constitutively dimeric full-length NEMO protein. The stability
of the NEMO coiled coil is maintained by strong interhelix interactions
in the region centered on residue 54. The disulfide-linked constructs
we describe herein may be useful for crystallization of NEMO’s
IKKβ binding domain in the absence of bound IKKβ, thereby
facilitating the structural characterization of small-molecule inhibitors.
Collapse
Affiliation(s)
- Li Zhou
- Department of Chemistry and ‡Department of Biology, Boston University , Boston, Massachusetts 02215, United States
| | | | | | | | | | | | | |
Collapse
|
10
|
Conte MI, Pescatore A, Paciolla M, Esposito E, Miano MG, Lioi MB, McAleer MA, Giardino G, Pignata C, Irvine AD, Scheuerle AE, Royer G, Hadj-Rabia S, Bodemer C, Bonnefont JP, Munnich A, Smahi A, Steffann J, Fusco F, Ursini MV. Insight intoIKBKG/NEMOLocus: Report of New Mutations and Complex Genomic Rearrangements Leading to Incontinentia Pigmenti Disease. Hum Mutat 2013; 35:165-77. [DOI: 10.1002/humu.22483] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Accepted: 11/05/2013] [Indexed: 12/24/2022]
Affiliation(s)
| | - Alessandra Pescatore
- Institute of Genetics and Biophysics ‘Adriano Buzzati-Traverso’; IGB-CNR; Naples Italy
| | - Mariateresa Paciolla
- Institute of Genetics and Biophysics ‘Adriano Buzzati-Traverso’; IGB-CNR; Naples Italy
| | - Elio Esposito
- Institute of Genetics and Biophysics ‘Adriano Buzzati-Traverso’; IGB-CNR; Naples Italy
| | | | | | - Maeve A. McAleer
- Department of Pediatric Dermatology; Our Lady's Children's Hospital; Crumlin, Dublin12 Ireland
- National Children's Research Centre; Our Lady's Children's Hospital Dublin; Crumlin, Dublin 12 Ireland
| | - Giuliana Giardino
- Department of Translational Medical Sciences; Federico II University; Naples 80131 Italy
| | - Claudio Pignata
- Department of Translational Medical Sciences; Federico II University; Naples 80131 Italy
| | - Alan D. Irvine
- Department of Pediatric Dermatology; Our Lady's Children's Hospital; Crumlin, Dublin12 Ireland
- National Children's Research Centre; Our Lady's Children's Hospital Dublin; Crumlin, Dublin 12 Ireland
- School of Medicine; Trinity College Dublin; Dublin Ireland
| | | | - Ghislaine Royer
- Department of Genetics; INSERM U781, Hôpital Necker-Enfants Malades; Paris France
| | - Smail Hadj-Rabia
- Department of Genetics; INSERM U781, Hôpital Necker-Enfants Malades; Paris France
| | - Christine Bodemer
- Department of Genetics; INSERM U781, Hôpital Necker-Enfants Malades; Paris France
| | - Jean-Paul Bonnefont
- Department of Genetics; INSERM U781, Hôpital Necker-Enfants Malades; Paris France
| | - Arnold Munnich
- Department of Genetics; INSERM U781, Hôpital Necker-Enfants Malades; Paris France
| | - Asma Smahi
- Department of Genetics; INSERM U781, Hôpital Necker-Enfants Malades; Paris France
| | - Julie Steffann
- Department of Genetics; INSERM U781, Hôpital Necker-Enfants Malades; Paris France
| | - Francesca Fusco
- Institute of Genetics and Biophysics ‘Adriano Buzzati-Traverso’; IGB-CNR; Naples Italy
| | | |
Collapse
|
11
|
Borthakur A, Bhattacharyya S, Kumar A, Anbazhagan AN, Tobacman JK, Dudeja PK. Lactobacillus acidophilus alleviates platelet-activating factor-induced inflammatory responses in human intestinal epithelial cells. PLoS One 2013; 8:e75664. [PMID: 24130731 PMCID: PMC3794005 DOI: 10.1371/journal.pone.0075664] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 08/16/2013] [Indexed: 02/06/2023] Open
Abstract
Probiotics have been used as alternative prevention and therapy modalities in intestinal inflammatory disorders including inflammatory bowel diseases (IBD) and necrotizing enterocolitis (NEC). Pathophysiology of IBD and NEC includes the production of diverse lipid mediators, including platelet-activating factor (PAF) that mediate inflammatory responses in the disease. PAF is known to activate NF-κB, however, the mechanisms of PAF-induced inflammation are not fully defined. We have recently described a novel PAF-triggered pathway of NF-κB activation and IL-8 production in intestinal epithelial cells (IECs), requiring the pivotal role of the adaptor protein Bcl10 and its interactions with CARMA3 and MALT1. The current studies examined the potential role of the probiotic Lactobacillus acidophilus in reversing the PAF-induced, Bcl10-dependent NF-κB activation and IL-8 production in IECs. PAF treatment (5 µM×24 h) of NCM460 and Caco-2 cells significantly increased nuclear p65 NF-κB levels and IL-8 secretion (2-3-fold, P<0.05), compared to control, which were blocked by pretreatment of the cells for 6 h with L. acidophilus (LA) or its culture supernatant (CS), followed by continued treatments with PAF for 24 h. LA-CS also attenuated PAF-induced increase in Bcl10 mRNA and protein levels and Bcl10 promoter activity. LA-CS did not alter PAF-induced interaction of Bcl10 with CARMA3, but attenuated Bcl10 interaction with MALT1 and also PAF-induced ubiquitination of IKKγ. Efficacy of bacteria-free CS of LA in counteracting PAF-induced inflammatory cascade suggests that soluble factor(s) in the CS of LA mediate these effects. These results define a novel mechanism by which probiotics counteract PAF-induced inflammation in IECs.
Collapse
Affiliation(s)
- Alip Borthakur
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Sumit Bhattacharyya
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Anoop Kumar
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Arivarasu Natarajan Anbazhagan
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Joanne K. Tobacman
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Pradeep K. Dudeja
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
- Jesse Brown VA Medical Center, Chicago, Illinois, United States of America
| |
Collapse
|
12
|
Abstract
The transcription factor NF-κB is a family of proteins involved in signaling pathways essential for normal cellular functions and development. Deletion of various components of this pathway resulted with abnormal skeletal development. Research in the last decade has established that NF-κB signaling mediates RANK ligand-induced osteoclastogenesis. Consistently, it was shown that inhibition of NF-κB was an effective approach to inhibit osteoclast formation and bone resorptive activity. Identification of the molecular machinery underlying NF-κB activation permitted osteoclast-specific deletion of the major components of this pathway. As a result, it was clear that deletion of members of the proximal IKK kinase complex and the distal NF-κB subunits and downstream regulators affected skeletal development. These studies provided several targets of therapeutic intervention in osteolytic diseases. NF-κB activity has been also described as the centerpiece of inflammatory responses and is considered a potent mediator of inflammatory osteolysis. Indeed, inflammatory insults exacerbate physiologic RANKL-induced NF-κB signals leading to exaggerated responses and to inflammatory osteolysis. These superimposed NF-κB activities appear to underlie several bone pathologies. This review will describe the individual roles of NF-κB molecules in bone resorption and inflammatory osteolysis.
Collapse
Affiliation(s)
- Y Abu-Amer
- Department of Orthopedic Surgery, Department of Cell Biology & Physiology, Washington University School of Medicine, 660S. Euclid Avenue, Saint Louis, MO 63110, USA.
| |
Collapse
|
13
|
Golden MS, Cote SM, Sayeg M, Zerbe BS, Villar EA, Beglov D, Sazinsky SL, Georgiadis RM, Vajda S, Kozakov D, Whitty A. Comprehensive experimental and computational analysis of binding energy hot spots at the NF-κB essential modulator/IKKβ protein-protein interface. J Am Chem Soc 2013; 135:6242-56. [PMID: 23506214 PMCID: PMC3680600 DOI: 10.1021/ja400914z] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We report a comprehensive analysis of binding energy hot spots at the protein-protein interaction (PPI) interface between nuclear factor kappa B (NF-κB) essential modulator (NEMO) and IκB kinase subunit β (IKKβ), an interaction that is critical for NF-κB pathway signaling, using experimental alanine scanning mutagenesis and also the FTMap method for computational fragment screening. The experimental results confirm that the previously identified NEMO binding domain (NBD) region of IKKβ contains the highest concentration of hot-spot residues, the strongest of which are W739, W741, and L742 (ΔΔG = 4.3, 3.5, and 3.2 kcal/mol, respectively). The region occupied by these residues defines a potentially druggable binding site on NEMO that extends for ~16 Å to additionally include the regions that bind IKKβ L737 and F734. NBD residues D738 and S740 are also important for binding but do not make direct contact with NEMO, instead likely acting to stabilize the active conformation of surrounding residues. We additionally found two previously unknown hot-spot regions centered on IKKβ residues L708/V709 and L719/I723. The computational approach successfully identified all three hot-spot regions on IKKβ. Moreover, the method was able to accurately quantify the energetic importance of all hot-spot residues involving direct contact with NEMO. Our results provide new information to guide the discovery of small-molecule inhibitors that target the NEMO/IKKβ interaction. They additionally clarify the structural and energetic complementarity between "pocket-forming" and "pocket-occupying" hot-spot residues, and further validate computational fragment mapping as a method for identifying hot spots at PPI interfaces.
Collapse
Affiliation(s)
- Mary S. Golden
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | - Shaun M. Cote
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | - Marianna Sayeg
- Department of Biomedical Engineering, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | - Brandon S. Zerbe
- Department of Biomedical Engineering, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | - Elizabeth A. Villar
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | - Dmitri Beglov
- Department of Biomedical Engineering, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | - Stephen L. Sazinsky
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | - Rosina M. Georgiadis
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | - Sandor Vajda
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
- Department of Biomedical Engineering, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | - Dima Kozakov
- Department of Biomedical Engineering, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | - Adrian Whitty
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| |
Collapse
|
14
|
Taylor KE, Mossman KL. Recent advances in understanding viral evasion of type I interferon. Immunology 2013; 138:190-7. [PMID: 23173987 PMCID: PMC3573272 DOI: 10.1111/imm.12038] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Revised: 10/11/2012] [Accepted: 11/14/2012] [Indexed: 12/21/2022] Open
Abstract
The type I interferon (IFN) system mediates a wide variety of antiviral effects and represents an important first barrier to virus infection. Consequently, viruses have developed an impressive diversity of tactics to circumvent IFN responses. Evasion strategies can involve preventing initial virus detection, via the disruption of the Toll‐like receptors or the retinoic acid inducible gene I (RIG‐I) ‐like receptors, or by avoiding the initial production of the ligands recognized by these receptors. An alternative approach is to preclude IFN production by disarming or degrading the transcription factors involved in the expression of IFN, such as interferon regulatory factor 3 (IRF3)/IRF7, nuclear factor‐κB (NF‐κB), or ATF‐2/c‐jun, or by inducing a general block on host cell transcription. Viruses also oppose IFN signalling, both by disturbing the type I IFN receptor and by impeding JAK/STAT signal transduction upon IFN receptor engagement. In addition, the global expression of IFN‐stimulated genes (ISGs) can be obstructed via interference with epigenetic signalling, and specific ISGs can also be selectively targeted for inhibition. Finally, some viruses disrupt IFN responses by co‐opting negative regulatory systems, whereas others use antiviral mechanisms to their own advantage. Here, we review recent developments in this field.
Collapse
Affiliation(s)
- Kathryne E Taylor
- Department of Biochemistry and Biomedical Sciences, McMaster Immunology Research Centre, Michael DeGroote Centre for Learning and Discovery, McMaster University, Hamilton, ON, Canada
| | | |
Collapse
|
15
|
Diverse roles of the ubiquitin system in NF-κB activation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1843:129-36. [PMID: 23523932 DOI: 10.1016/j.bbamcr.2013.03.011] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2012] [Revised: 02/15/2013] [Accepted: 03/10/2013] [Indexed: 12/13/2022]
Abstract
NF-κB is a transcription factor known to be involved in pleomorphic biological phenomena such as inflammation and immune responses. Abnormal activation of NF-κB has been reported in many pathological conditions, including allergic and auto-inflammatory diseases and malignancies. Therefore, the NF-κB activation pathway has been extensively studied and involvement of the ubiquitin conjugation system in the NF-κB activation pathways has been shown. Also non-degradable roles of the ubiquitin system have been revealed, recently. Several types of polyubiquitin chains exist and the type of chain seems to determine how ubiquitinated proteins are regulated. Roles of non-degradable types of polyubiquitin chains such as K63, linear and K11 chains in NF-κB activation is one of the big issues in NF-κB research. Thus, this short article discusses the differential roles of those polyubiquitin chains in NF-κB activation. This article is part of a Special Issue entitled: Ubiquitin-Proteasome System. Guest Editors: Thomas Sommer and Dieter H. Wolf.
Collapse
|
16
|
p47 negatively regulates IKK activation by inducing the lysosomal degradation of polyubiquitinated NEMO. Nat Commun 2013; 3:1061. [PMID: 22990857 DOI: 10.1038/ncomms2068] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Accepted: 08/15/2012] [Indexed: 12/18/2022] Open
Abstract
The persistent or excess activation of NF-κB causes various inflammatory and autoimmune diseases, but the molecular mechanisms that negatively regulate NF-κB activation are not fully understood. Here we show that p47, an essential factor for Golgi membrane fusion, associates with the NEMO subunit of the IκB kinase (IKK) complex upon TNF-α or IL-1 stimulation, and inhibits IKK activation. p47 binds to Lys63-linked and linear polyubiquitin chains, which are conjugated to NEMO upon such stimulation. The binding of p47 to polyubiquitinated NEMO triggers the lysosomal degradation of NEMO, thereby inhibiting IKK activation. The silencing of p47 results in enhanced TNF-α- or IL-1-induced IKK activation, and an increased expression of genes encoding inflammatory mediators. Taken together, our results suggest that p47 is critical for negatively regulating stimulation-induced IKK activation in a manner that is mechanistically distinct from the previously characterized negative regulators, such as A20 and CYLD.
Collapse
|
17
|
Kachaner D, Génin P, Laplantine E, Weil R. Toward an integrative view of Optineurin functions. Cell Cycle 2012; 11:2808-18. [PMID: 22801549 DOI: 10.4161/cc.20946] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
This review highlights recent advances in our understanding of the mechanisms of Optineurin (Optn) action and its implication in diseases. Optn has emerged as a key player regulating various physiological processes, including membrane trafficking, protein secretion, cell division and host defense against pathogens. Furthermore, there is growing evidence for an association of Optn mutations with human diseases such as primary open-angle glaucoma, amyotrophic lateral sclerosis and Paget's disease of bone. Optn functions depend on its precise subcellular localization and its interaction with other proteins. Here, we review the mechanisms that allow Optn to ensure a timely and spatially coordinated integration of different physiological processes and discuss how their deregulation may lead to different pathologies.
Collapse
Affiliation(s)
- David Kachaner
- Institut Pasteur, Unité de Signalisation Moléculaire et Activation Cellulaire, CNRS URA 2582, Paris, France
| | | | | | | |
Collapse
|
18
|
Iwai K. Diverse ubiquitin signaling in NF-κB activation. Trends Cell Biol 2012; 22:355-64. [DOI: 10.1016/j.tcb.2012.04.001] [Citation(s) in RCA: 121] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2012] [Revised: 04/01/2012] [Accepted: 04/03/2012] [Indexed: 10/28/2022]
|
19
|
Chadwick L, Gentle L, Strachan J, Layfield R. Review: unchained maladie - a reassessment of the role of Ubb(+1) -capped polyubiquitin chains in Alzheimer's disease. Neuropathol Appl Neurobiol 2012; 38:118-31. [PMID: 22082077 DOI: 10.1111/j.1365-2990.2011.01236.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Molecular misreading allows the formation of mutant proteins in the absence of gene mutations. A mechanism has been proposed by which a frameshift mutant of the ubiquitin protein, Ubb(+1) , which accumulates in an age-dependent manner as a result of molecular misreading, contributes to neuropathology in Alzheimer's disease (Lam et al. 2000). Specifically, in the Ubb(+1) -mediated proteasome inhibition hypothesis Ubb(+1) 'caps' unanchored (that is, nonsubstrate linked) polyubiquitin chains, which then act as dominant inhibitors of the 26S proteasome. A review of subsequent literature indicates that this original hypothesis is broadly supported, and offers new insights into the mechanisms accounting for the age-dependent accumulation of Ubb(+1) , and how Ubb(+1) -mediated proteasome inhibition may contribute to Alzheimer's disease. Further, recent studies have highlighted a physiological role for free endogenous unanchored polyubiquitin chains in the direct activation of certain protein kinases. This raises the possibility that Ubb(+1) -capped unanchored polyubiquitin chains could also exert harmful effects through the aberrant activation of tau or other ubiquitin-dependent kinases, neuronal NF-κB activity or NF-κB-mediated neuroinflammatory processes.
Collapse
Affiliation(s)
- L Chadwick
- School of Biomedical Sciences, University of Nottingham, UK
| | | | | | | |
Collapse
|
20
|
Schmukle AC, Walczak H. No one can whistle a symphony alone – how different ubiquitin linkages cooperate to orchestrate NF-κB activity. J Cell Sci 2012; 125:549-59. [DOI: 10.1242/jcs.091793] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Although it has been known for a long time that ubiquitylation has a major role in the activation and regulation of the nuclear factor kappa B (NF-κB) pathway, recent studies have revealed that the picture is a lot more complex than originally thought. NF-κB and ubiquitylation initially became linked when it was recognised that lysine (K)48-linked ubiquitin chains are involved in the processing of NF-κB precursors and the degradation of inhibitor of kappa B (IκB) proteins. Soon thereafter, it was reported that K63-linked chains were involved in the assembly of IκB kinase (IKK)-activating complexes and required for activation of the NF-κB signalling pathway. Recently, the discovery that atypical ubiquitin linkages, including linear and K11 linkages, are also involved in the activation of NF-κB has led to the need to re-evaluate existing models of how activation of this transcription factor is initiated and regulated. It is now becoming apparent that not only the canonical types of ubiquitin chains but possibly all linkage types have to be investigated in order to fully comprehend NF-κB activation. This can be considered a turning point in our view of the regulation of one of the most important pathways of gene induction. Hence, in this Commentary, we summarise the information that is currently available and incorporate it into a new model of NF-κB activation, thereby highlighting the emerging new challenges in understanding the role of ubiquitylation in NF-κB activation.
Collapse
Affiliation(s)
- Anna C. Schmukle
- Tumour Immunology Unit, Division of Immunology and Inflammation, Department of Medicine, Imperial College London, 10th floor, Commonwealth Building, Du Cane Road, London W12 0NN, UK
| | - Henning Walczak
- Tumour Immunology Unit, Division of Immunology and Inflammation, Department of Medicine, Imperial College London, 10th floor, Commonwealth Building, Du Cane Road, London W12 0NN, UK
| |
Collapse
|
21
|
Biard-Piechaczyk M, Borel S, Espert L, de Bettignies G, Coux O. HIV-1, ubiquitin and ubiquitin-like proteins: the dialectic interactions of a virus with a sophisticated network of post-translational modifications. Biol Cell 2012; 104:165-87. [PMID: 22188301 DOI: 10.1111/boc.201100112] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Accepted: 12/14/2011] [Indexed: 11/26/2022]
Abstract
The modification of intracellular proteins by ubiquitin (Ub) and ubiquitin-like (UbL) proteins is a central mechanism for regulating and fine-tuning all cellular processes. Indeed, these modifications are widely used to control the stability, activity and localisation of many key proteins and, therefore, they are instrumental in regulating cellular functions as diverse as protein degradation, cell signalling, vesicle trafficking and immune response. It is thus no surprise that pathogens in general, and viruses in particular, have developed multiple strategies to either counteract or exploit the complex mechanisms mediated by the Ub and UbL protein conjugation pathways. The aim of this review is to provide an overview on the intricate and conflicting relationships that intimately link HIV-1 and these sophisticated systems of post-translational modifications.
Collapse
Affiliation(s)
- Martine Biard-Piechaczyk
- Centre d'étude d'agents Pathogènes et Biotechnologies pour la Santé (CPBS-CNRS), Montpellier Cedex 5, France.
| | | | | | | | | |
Collapse
|
22
|
König HG, Fenner BJ, Byrne JC, Schwamborn RF, Bernas T, Jefferies CA, Prehn JHM. Fibroblast growth factor homologous factor 1 interacts with NEMO to regulate NF-κB signaling in neurons. J Cell Sci 2012; 125:6058-70. [DOI: 10.1242/jcs.111880] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Neuronal survival and plasticity critically depend on constitutive activity of the transcription factor nuclear factor-κB (NF-κB). We here describe a role for a small intracellular fibroblast growth factor homologue, the fibroblast growth factor homologous factor 1 (FHF1/FGF12) in the regulation of NF-κB activity in mature neurons. FHF's have previously been described to control neuronal excitability, and mutations in FHF isoforms give rise to a form of progressive spinocerebellar ataxia. Using a protein-array approach, we identified FHF1b as a novel interactor of the canonical NF–κB modulator IKKγ/NEMO. Co-immunoprecipitation, pull-down and GAL4-reporter experiments, as well as proximity ligation assays confirmed the interaction of FHF1 and NEMO, and demonstrated that a major site of interaction occurred within the axon initial segment. Fhf1 gene silencing strongly activated neuronal NF-κB activity and increased neurite lengths, branching patterns and spine counts in mature cortical neurons. The effects of FHF1 on neuronal NF-κB activity and morphology required the presence of NEMO. Our results imply that FHF1 negatively regulates the constitutive NF-κB activity in neurons.
Collapse
|
23
|
Emmerich CH, Schmukle AC, Walczak H. The Emerging Role of Linear Ubiquitination in Cell Signaling. Sci Signal 2011; 4:re5. [DOI: 10.1126/scisignal.2002187] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
|
24
|
Chang EJ, Ha J, Kang SS, Lee ZH, Kim HH. AWP1 binds to tumor necrosis factor receptor-associated factor 2 (TRAF2) and is involved in TRAF2-mediated nuclear factor-kappaB signaling. Int J Biochem Cell Biol 2011; 43:1612-20. [DOI: 10.1016/j.biocel.2011.07.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Revised: 07/15/2011] [Accepted: 07/20/2011] [Indexed: 10/17/2022]
|
25
|
Shibata Y, Tanaka Y, Gohda J, Inoue JI. Activation of the IκB kinase complex by HTLV-1 Tax requires cytosolic factors involved in Tax-induced polyubiquitination. J Biochem 2011; 150:679-86. [PMID: 21862596 DOI: 10.1093/jb/mvr106] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Activation of NF-κB by human T cell leukaemia virus type 1 Tax is thought to be crucial in T-cell transformation and the onset of adult T cell leukaemia. Tax activates NF-κB through activation of the IκB kinase (IKK) complex, similar to cytokine-induced NF-κB activation, which involves active signalling complex formation using polyubiquitin chains as a platform. Although polyubiquitination of Tax was reported to be required for IKK activation, most studies have been performed using intact cells, in which secondary NF-κB activation can be induced by various cytokines that are secreted due to Tax-mediated primary NF-κB activation. Therefore, a cell-free assay system, in which IKK can be activated by adding highly purified recombinant Tax to cytosolic extract, was used to analyse Tax-induced IKK activation. In contrast to the cytosolic extract, the purified IKK complex was not activated by Tax, whereas, it was efficiently activated by MEKK1, that does not require polyubiquitination to activate IKK. Moreover, Tax-induced IKK activation was blocked when the cytosolic extract was mixed with either lysine-free, methylated or K63R ubiquitin. These results obtained through our cell-free assay suggest that K63-linked polyubiquitination is critical, but linear polyubiquitination is dispensable or insufficient for Tax-induced IKK activation.
Collapse
Affiliation(s)
- Yuri Shibata
- Department of Cancer Biology, Division of Cellular and Molecular Biology, Institute of Medical Science, University of Tokyo, Shirokane-dai, Minato-ku, Tokyo 108-8639, Japan
| | | | | | | |
Collapse
|
26
|
Verhelst K, Verstrepen L, Carpentier I, Beyaert R. Linear ubiquitination in NF-κB signaling and inflammation: What we do understand and what we do not. Biochem Pharmacol 2011; 82:1057-65. [PMID: 21787758 DOI: 10.1016/j.bcp.2011.07.066] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Revised: 07/03/2011] [Accepted: 07/07/2011] [Indexed: 10/17/2022]
Abstract
Despite its small size, ubiquitin is one of the most versatile signaling molecules in the cell and affects distinct cellular processes. It forms the building block of a repertoire of posttranslational modifications of cellular proteins, ranging from the attachment of a single ubiquitin to ubiquitin chains of different linkage. Proteins that contain ubiquitin chain-specific ubiquitin-binding domains recognize different types of ubiquitination and determine the mode of signaling of modified proteins. Polyubiquitin chains were thought to be formed only by the conjugation of the ubiquitin C-terminal Gly to one of the seven internal Lys residues of another ubiquitin. However, the C-terminal Gly was recently shown to also link to the N-terminus of another ubiquitin to form head-to-tail polyubiquitin chains, which is referred to as linear ubiquitination. These linear linkages can be assembled and conjugated to another protein by an E3 ligase complex known as LUBAC, and are recognized by a particular ubiquitin-binding domain known as UBAN. Both have been implicated in the regulation of TNF-induced NF-κB signaling, which induces the expression of a wide range of proteins that mediate many biological processes including inflammation and cell survival. We discuss the molecular players and mechanisms that determine the specificity and outcome of linear ubiquitination in NF-κB signaling, as well as future directions and challenges ahead.
Collapse
Affiliation(s)
- Kelly Verhelst
- Department for Molecular Biomedical Research, Unit of Molecular Signal Transduction in Inflammation, VIB, Ghent, Belgium
| | | | | | | |
Collapse
|
27
|
Bedford L, Lowe J, Dick LR, Mayer RJ, Brownell JE. Ubiquitin-like protein conjugation and the ubiquitin-proteasome system as drug targets. Nat Rev Drug Discov 2010; 10:29-46. [PMID: 21151032 PMCID: PMC7097807 DOI: 10.1038/nrd3321] [Citation(s) in RCA: 433] [Impact Index Per Article: 30.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Ubiquitin is a highly conserved 76 amino-acid protein that covalently attaches to protein substrates targeted for degradation by the 26S proteasome. The coordinated effort of a series of enzymes, including an activating enzyme (E1), a conjugating enzyme (E2) and a ligase (E3), uses ATP to ultimately form an isopeptide bond between ubiquitin and a substrate. Another class of enzymes called deubiquitylating enzymes (DUBs) deconstruct these linkages and also have an essential role in ubiquitin function. In addition, ubiquitin-like proteins (UBLs), including NEDD8, SUMO and ISG15, share a characteristic three-dimensional fold with ubiquitin but have their own dedicated enzyme cascades and distinct (although sometimes overlapping) biological functions. The ubiquitin–proteasome system (UPS) and UBL conjugation pathways have important roles in various human diseases, including numerous types of cancer, cardiovascular disease, viral diseases and neurodegenerative disorders. The proteasome inhibitor bortezomib (Velcade; Millennium Pharmaceuticals) is the first clinically validated drug to target the UPS and is approved for the treatment of multiple myeloma. This suggests that other diseases may conceivably be targeted by modulating components of the UPS and UBL conjugation pathways using small-molecule inhibitors. A significant hurdle to identifying drug-like inhibitors of enzyme targets within the UPS and UBL conjugation pathways is the limited understanding of the molecular mechanisms and biological consequences of UBL conjugation. Here, we provide an overview of the enzyme classes in the UPS and UBL pathways that are potential therapeutic targets, and highlight considerations that are important for drug discovery. We also discuss the progress in the development of small-molecule inhibitors, and review developments in understanding of the role of the components of the UPS and the UBL pathways in disease and their potential for therapeutic intervention.
The ubiquitin–proteasome system (UPS) and ubiquitin-like protein (UBL) conjugation pathways are integral to cellular protein homeostasis, and their functional importance in various diseases, including cancer, cardiovascular disease and neurodegenerative disorders, is now beginning to emerge. Brownell and colleagues review developments in understanding of the role of the components of the UPS and the UBL pathways in disease and their potential for therapeutic intervention. The ubiquitin–proteasome system (UPS) and ubiquitin-like protein (UBL) conjugation pathways are integral to cellular protein homeostasis. The growing recognition of the fundamental importance of these pathways to normal cell function and in disease has prompted an in-depth search for small-molecule inhibitors that selectively block the function of these pathways. However, our limited understanding of the molecular mechanisms and biological consequences of UBL conjugation is a significant hurdle to identifying drug-like inhibitors of enzyme targets within these pathways. Here, we highlight recent advances in understanding the role of some of these enzymes and how these new insights may be the key to developing novel therapeutics for diseases including immuno-inflammatory disorders, cancer, infectious diseases, cardiovascular disease and neurodegenerative disorders.
Collapse
Affiliation(s)
- Lynn Bedford
- School of Biomedical Sciences, University of Nottingham, Nottingham, UK.
| | | | | | | | | |
Collapse
|
28
|
Abstract
Best known for its role in targeting protein degradation by the proteasome, ubiquitin modification has also emerged as an important mechanism that regulates cell signaling through proteasome-independent mechanisms. The role of ubiquitin as a versatile signaling tag is characteristically illustrated in the NF-κB pathways, which regulate a variety of physiological and pathological processes in response to diverse stimuli. Here, we review the role of ubiquitination in different steps of the NF-κB signaling cascades, focusing on recent advances in understanding the mechanisms of protein kinase activation by polyubiquitin chains in different pathways that converge on NF-κB.
Collapse
|