51
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cIAP1 regulates TNF-mediated cdc42 activation and filopodia formation. Oncogene 2013; 33:5534-45. [DOI: 10.1038/onc.2013.499] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Revised: 09/20/2013] [Accepted: 10/21/2013] [Indexed: 02/08/2023]
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52
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Lecis D, De Cesare M, Perego P, Conti A, Corna E, Drago C, Seneci P, Walczak H, Colombo MP, Delia D, Sangaletti S. Smac mimetics induce inflammation and necrotic tumour cell death by modulating macrophage activity. Cell Death Dis 2013; 4:e920. [PMID: 24232096 PMCID: PMC3847325 DOI: 10.1038/cddis.2013.449] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 10/11/2013] [Accepted: 10/15/2013] [Indexed: 12/30/2022]
Abstract
Smac mimetics (SMs) comprise a class of small molecules that target members of the inhibitor of apoptosis family of pro-survival proteins, whose expression in cancer cells hinders the action of conventional chemotherapeutics. Herein, we describe the activity of SM83, a newly synthesised dimeric SM, in two cancer ascites models: athymic nude mice injected intraperitoneally with IGROV-1 human ovarian carcinoma cells and immunocompetent BALB/c mice injected with murine Meth A sarcoma cells. SM83 rapidly killed ascitic IGROV-1 and Meth A cells in vivo (prolonging mouse survival), but was ineffective against the same cells in vitro. IGROV-1 cells in nude mice were killed within the ascites by a non-apoptotic, tumour necrosis factor (TNF)-dependent mechanism. SM83 administration triggered a rapid inflammatory event characterised by host secretion of TNF, interleukin-1β and interferon-γ. This inflammatory response was associated with the reversion of the phenotype of tumour-associated macrophages from a pro-tumoural M2- to a pro-inflammatory M1-like state. SM83 treatment was also associated with a massive recruitment of neutrophils that, however, was not essential for the antitumoural activity of this compound. In BALB/c mice bearing Meth A ascites, SM83 treatment was in some cases curative, and these mice became resistant to a second injection of cancer cells, suggesting that they had developed an adaptive immune response. Altogether, these results indicate that, in vivo, SM83 modulates the immune system within the tumour microenvironment and, through its pro-inflammatory action, leads cancer cells to die by necrosis with the release of high-mobility group box-1. In conclusion, our work provides evidence that SMs could be more therapeutically active than expected by stimulating the immune system.
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Affiliation(s)
- D Lecis
- Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan 20133, Italy
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53
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IAPs on the move: role of inhibitors of apoptosis proteins in cell migration. Cell Death Dis 2013; 4:e784. [PMID: 24008728 PMCID: PMC3789170 DOI: 10.1038/cddis.2013.311] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Accepted: 07/09/2013] [Indexed: 01/06/2023]
Abstract
Inhibitors of Apoptosis Proteins (IAPs) are a class of highly conserved proteins predominantly known for the regulation of caspases and immune signaling. However, recent evidence suggests a crucial role for these molecules in the regulation of tumor cell shape and migration by controlling MAPK, NF-κB and Rho GTPases. IAPs directly control Rho GTPases, thus regulating cell shape and migration. For instance, XIAP and cIAP1 function as the direct E3 ubiquitin ligases of Rac1 and target it for proteasomal degradation. IAPs are differentially expressed in tumor cells and have been targeted by several cancer therapeutic drugs that are currently in clinical trials. Here, we summarize the current knowledge on the role of IAPs in the regulation of cell migration and discuss the possible implications of these observations in regulating tumor cell metastases.
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54
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Duda DM, Olszewski JL, Schuermann JP, Kurinov I, Miller DJ, Nourse A, Alpi AF, Schulman BA. Structure of HHARI, a RING-IBR-RING ubiquitin ligase: autoinhibition of an Ariadne-family E3 and insights into ligation mechanism. Structure 2013; 21:1030-41. [PMID: 23707686 DOI: 10.1016/j.str.2013.04.019] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2013] [Revised: 04/25/2013] [Accepted: 04/29/2013] [Indexed: 12/20/2022]
Abstract
A distinct mechanism for ubiquitin (Ub) ligation has recently been proposed for the RING1-IBR-RING2 (RBR) family of E3s: an N-terminal RING1 domain recruits a thioester-linked intermediate complex between Ub and the E2 UbcH7, and a structurally distinct C-terminal RING2 domain displays a catalytic cysteine required for Ub ligation. To obtain insights into RBR E3s, we determined the crystal structure of the human homolog of Ariadne (HHARI), which reveals the individual RING1, IBR, and RING2 domains embedded in superdomains involving sequences specific to the Ariadne RBR subfamily. The central IBR is flanked on one side by RING1, which is exposed and binds UbcH7. On the other side, a C-terminal autoinhibitory "Ariadne domain" masks the RING2 active site. Insights into RBR E3 mechanisms are provided by structure-based mutations that indicate distinct steps of relief from autoinhibition, Ub transfer from E2 to HHARI, and ligation from the HHARI cysteine to a terminal acceptor.
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Affiliation(s)
- David M Duda
- Howard Hughes Medical Institute, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
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55
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Chen KE, Richards AA, Caradoc-Davies TT, Vajjhala PR, Robin G, Lua LHL, Hill JM, Schroder K, Sweet MJ, Kellie S, Kobe B, Martin J. The structure of the caspase recruitment domain of BinCARD reveals that all three cysteines can be oxidized. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2013; 69:774-84. [PMID: 23633586 DOI: 10.1107/s0907444913001558] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 01/16/2013] [Indexed: 11/10/2022]
Abstract
The caspase recruitment domain (CARD) is present in death-domain superfamily proteins involved in inflammation and apoptosis. BinCARD is named for its ability to interact with Bcl10 and inhibit downstream signalling. Human BinCARD is expressed as two isoforms that encode the same N-terminal CARD region but which differ considerably in their C-termini. Both isoforms are expressed in immune cells, although BinCARD-2 is much more highly expressed. Crystals of the CARD fold common to both had low symmetry (space group P1). Molecular replacement was unsuccessful in this low-symmetry space group and, as the construct contains no methionines, first one and then two residues were engineered to methionine for MAD phasing. The double-methionine variant was produced as a selenomethionine derivative, which was crystallized and the structure was solved using data measured at two wavelengths. The crystal structures of the native and selenomethionine double mutant were refined to high resolution (1.58 and 1.40 Å resolution, respectively), revealing the presence of a cis-peptide bond between Tyr39 and Pro40. Unexpectedly, the native crystal structure revealed that all three cysteines were oxidized. The mitochondrial localization of BinCARD-2 and the susceptibility of its CARD region to redox modification points to the intriguing possibility of a redox-regulatory role.
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Affiliation(s)
- Kai En Chen
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
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56
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Abstract
Inhibitors of Apoptosis Proteins (IAPs) are well-studied E3 ubiquitin ligases predominantly known for regulation of apoptosis. We uncovered that IAPs can function as a direct E3 ubiquitin ligase of RhoGTPase Rac1. cIAP1 and XIAP directly conjugate polyubiquitin chains to Lysine 147 of activated Rac1 and target it for proteasomal degradation. Consistently, loss of these IAPs by various strategies led to stabilization of Rac1 and mesenchymal mode of migration in tumor cells. IAPs also regulate Rac1 degradation upon RhoGDI1 depletion and CNF1 toxin treatment. Our observations revealed an evolutionarily conserved role of IAPs in regulating Rac1 stability shedding light on to the mechanisms behind ubiquitination–dependent inactivation of Rac1 signaling.
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Affiliation(s)
- Tripat Kaur Oberoi-Khanuja
- Emmy Noether Group of the DFG, Institute of Biochemistry II, Goethe University Medical School; Frankfurt, Germany
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57
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Identification of non-canonical NF-κB signaling as a critical mediator of Smac mimetic-stimulated migration and invasion of glioblastoma cells. Cell Death Dis 2013; 4:e564. [PMID: 23538445 PMCID: PMC3615728 DOI: 10.1038/cddis.2013.70] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
As inhibitor of apoptosis (IAP) proteins can regulate additional signaling pathways beyond apoptosis, we investigated the effect of the second mitochondrial activator of caspases (Smac) mimetic BV6, which antagonizes IAP proteins, on non-apoptotic functions in glioblastoma (GBM). Here, we identify non-canonical nuclear factor-κB (NF-κB) signaling and a tumor necrosis factor-α (TNFα)/TNF receptor 1 (TNFR1) autocrine/paracrine loop as critical mediators of BV6-stimulated migration and invasion of GBM cells. In addition to GBM cell lines, BV6 triggers cell elongation, migration and invasion in primary, patient-derived GBM cells at non-toxic concentrations, which do not affect cell viability or proliferation, and also increases infiltrative tumor growth in vivo underscoring the relevance of these findings. Molecular studies reveal that BV6 causes rapid degradation of cellular IAP proteins, accumulation of NIK, processing of p100 to p52, translocation of p52 into the nucleus, increased NF-κB DNA binding and enhanced NF-κB transcriptional activity. Electrophoretic mobility shift assay supershift shows that the NF-κB DNA-binding subunits consist of p50, p52 and RelB further confirming the activation of the non-canonical NF-κB pathway. BV6-stimulated NF-κB activation leads to elevated mRNA levels of TNFα and additional NF-κB target genes involved in migration (i.e., interleukin 8, monocyte chemoattractant protein 1, CXC chemokine receptor 4) and invasion (i.e., matrix metalloproteinase-9). Importantly, inhibition of NF-κB by overexpression of dominant-negative IκBα superrepressor prevents the BV6-stimulated cell elongation, migration and invasion. Similarly, specific inhibition of non-canonical NF-κB signaling by RNA interference-mediated silencing of NIK suppresses the BV6-induced cell elongation, migration and invasion as well as upregulation of NF-κB target genes. Intriguingly, pharmacological or genetic inhibition of the BV6-stimulated TNFα autocrine/paracrine loop by the TNFα-blocking antibody Enbrel or by knockdown of TNFR1 abrogates BV6-induced cell elongation, migration and invasion. By demonstrating that the Smac mimetic BV6 at non-toxic concentrations promotes migration and invasion of GBM cells via non-canonical NF-κB signaling, our findings have important implications for the use of Smac mimetics as cancer therapeutics.
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Berthelet J, Dubrez L. Regulation of Apoptosis by Inhibitors of Apoptosis (IAPs). Cells 2013; 2:163-87. [PMID: 24709650 PMCID: PMC3972657 DOI: 10.3390/cells2010163] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 03/04/2013] [Accepted: 03/05/2013] [Indexed: 01/05/2023] Open
Abstract
Abstract Inhibitors of Apoptosis (IAPs) are a family of proteins with various biological functions including regulation of innate immunity and inflammation, cell proliferation, cell migration and apoptosis. They are characterized by the presence of at least one N-terminal baculoviral IAP repeat (BIR) domain involved in protein-protein interaction. Most of them also contain a C-terminal RING domain conferring an E3-ubiquitin ligase activity. In drosophila, IAPs are essential to ensure cell survival, preventing the uncontrolled activation of the apoptotic protease caspases. In mammals, IAPs can also regulate apoptosis through controlling caspase activity and caspase-activating platform formation. Mammalian IAPs, mainly X-linked IAP (XIAP) and cellular IAPs (cIAPs) appeared to be important determinants of the response of cells to endogenous or exogenous cellular injuries, able to convert the survival signal into a cell death-inducing signal. This review highlights the role of IAP in regulating apoptosis in Drosophila and Mammals.
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Affiliation(s)
- Jean Berthelet
- Institut National de la Santé et de la Recherche Médicale (Inserm), UMR866, Dijon F-21079, France.
| | - Laurence Dubrez
- Institut National de la Santé et de la Recherche Médicale (Inserm), UMR866, Dijon F-21079, France.
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59
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Regulation of cell migration, invasion and metastasis by IAP proteins and their antagonists. Oncogene 2013; 33:671-6. [PMID: 23474760 DOI: 10.1038/onc.2013.63] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 01/02/2013] [Accepted: 01/03/2013] [Indexed: 12/22/2022]
Abstract
Inhibitor of apoptosis (IAP) proteins are a family comprised of a total of eight mammalian members that were initially described to act as endogenous inhibitors of caspases. In addition, extensive evidence has been accumulated over the last years showing that IAP proteins can regulate various signal transduction pathways, thereby exerting non-apoptotic functions beyond the inhibition of apoptosis. For example, IAP proteins have been implied in the control of cell motility, migration, invasion and metastasis. However, currently the question is controversially discussed whether or not they positively or negatively control these processes. As small-molecule inhibitors of IAP proteins have entered the stage of clinical evaluation as experimental cancer therapeutics, a better understanding of their various cellular effects will be critical for their rational use in the treatment of human diseases.
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60
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Roscioli E, Hamon R, Lester S, Murgia C, Grant J, Zalewski P. Zinc-rich inhibitor of apoptosis proteins (IAPs) as regulatory factors in the epithelium of normal and inflamed airways. Biometals 2013; 26:205-27. [PMID: 23460081 DOI: 10.1007/s10534-013-9618-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 02/25/2013] [Indexed: 11/25/2022]
Abstract
Integrity of the airway epithelium (AE) is important in the context of inhaled allergens and noxious substances, particularly during asthma-related airway inflammation where there is increased vulnerability of the AE to cell death. Apoptosis involves a number of signaling pathways which activate procaspases leading to cleavage of critical substrates. Understanding the factors which regulate AE caspases is important for development of strategies to minimize AE damage and airway inflammation, and therefore to better control asthma. One such factor is the essential dietary metal zinc. Zinc deficiency results in enhanced AE apoptosis, and worsened airway inflammation. This has implications for asthma, where abnormalities in zinc homeostasis have been observed. Zinc is thought to suppress the steps involved in caspase-3 activation. One target of zinc is the family of inhibitor of apoptosis proteins (IAPs) which are endogenous regulators of caspases. More studies are needed to identify the roles of IAPs in regulating apoptosis in normal and inflamed airways and to study their interaction with labile zinc ions. This new information will provide a framework for future clinical studies aimed at monitoring and management of airway zinc levels as well as minimising airway damage and inflammation in asthma.
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Affiliation(s)
- Eugene Roscioli
- Discipline of Medicine, The Basil Hetzel Institute for Translational Research, The Queen Elizabeth Hospital, University of Adelaide, Woodville, SA, 5011, Australia.
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61
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Silke J, Meier P. Inhibitor of apoptosis (IAP) proteins-modulators of cell death and inflammation. Cold Spring Harb Perspect Biol 2013; 5:5/2/a008730. [PMID: 23378585 DOI: 10.1101/cshperspect.a008730] [Citation(s) in RCA: 216] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Misregulated innate immune signaling and cell death form the basis of much human disease pathogenesis. Inhibitor of apoptosis (IAP) protein family members are frequently overexpressed in cancer and contribute to tumor cell survival, chemo-resistance, disease progression, and poor prognosis. Although best known for their ability to regulate caspases, IAPs also influence ubiquitin (Ub)-dependent pathways that modulate innate immune signaling via activation of nuclear factor κB (NF-κB). Recent research into IAP biology has unearthed unexpected roles for this group of proteins. In addition, the advances in our understanding of the molecular mechanisms that IAPs use to regulate cell death and innate immune responses have provided new insights into disease states and suggested novel intervention strategies. Here we review the functions assigned to those IAP proteins that act at the intersection of cell death regulation and inflammatory signaling.
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Affiliation(s)
- John Silke
- The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria 3052, Australia.
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62
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Abstract
Members of the tumor necrosis factor receptor superfamily play key roles in innate and adaptive immunity. Here, we review recent structural studies in the intracellular signal transduction of these receptors. A central theme revealed from these structural studies is that upon ligand binding, multiple intracellular proteins form higher-order signaling machines to transduce and amplify receptor activation information to different cellular fates, including NF-κB activation, apoptosis, and programmed necrosis. These studies open a new vista for understanding the biophysical principles in these signaling cascades.
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Affiliation(s)
- Jixi Li
- Program in Cellular and Molecular Medicine, Boston Children's Hospital and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, USA
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63
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Cossu F, Milani M, Vachette P, Malvezzi F, Grassi S, Lecis D, Delia D, Drago C, Seneci P, Bolognesi M, Mastrangelo E. Structural insight into inhibitor of apoptosis proteins recognition by a potent divalent smac-mimetic. PLoS One 2012; 7:e49527. [PMID: 23166698 PMCID: PMC3499469 DOI: 10.1371/journal.pone.0049527] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Accepted: 10/10/2012] [Indexed: 11/18/2022] Open
Abstract
Genetic alterations enhancing cell survival and suppressing apoptosis are hallmarks of cancer that significantly reduce the efficacy of chemotherapy or radiotherapy. The Inhibitor of Apoptosis Protein (IAP) family hosts conserved proteins in the apoptotic pathway whose over-expression, frequently found in tumours, potentiates survival and resistance to anticancer agents. In humans, IAPs comprise eight members hosting one or more structural Baculoviral IAP Repeat (BIR) domains. Cellular IAPs (cIAP1 and 2) indirectly inhibit caspase-8 activation, and regulate both the canonical and the non-canonical NF-κB signaling pathways. In contrast to cIAPs, XIAP (X chromosome-linked Inhibitor of Apoptosis Protein) inhibits directly the effector caspases-3 and -7 through its BIR2 domain, and initiator caspase-9 through its BIR3 domain; molecular docking studies suggested that Smac/DIABLO antagonizes XIAP by simultaneously targeting both BIR2 and BIR3 domains. Here we report analytical gel filtration, crystallographic and SAXS experiments on cIAP1-BIR3, XIAP-BIR3 and XIAP-BIR2BIR3 domains, alone and in the presence of compound 9a, a divalent homodimeric Smac mimetic. 9a is shown to bind two BIR domains inter- (in the case of two BIR3) and intra-molecularly (in the case of XIAP-BIR2BIR3), with higher affinity for cIAP1-BIR3, relative to XIAP-BIR3. Despite the different crystal lattice packing, 9a maintains a right handed helical conformation in both cIAP1-BIR3 and XIAP-BIR3 crystals, that is likely conserved in solution as shown by SAXS data. Our structural results demonstrate that the 9a linker length, its conformational degrees of freedom and its hydrophobicity, warrant an overall compact structure with optimal solvent exposure of its two active moieties for IAPs binding. Our results show that 9a is a good candidate for pre-clinical and clinical studies, worth of further investigations in the field of cancer therapy.
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Affiliation(s)
- Federica Cossu
- Department of Biosciences, University of Milano, Milano, Italy
| | - Mario Milani
- Department of Biosciences, University of Milano, Milano, Italy
- CNR-Istituto di Biofisica, Università degli Studi di Milano, Milano, Italy
| | - Patrice Vachette
- Institut de Biochimie et de Biophysique Moléculaire et Cellulaire, UMR8619 CNRS, Université Paris-Sud, IFR115, Orsay, France
| | | | - Serena Grassi
- Department of Biosciences, University of Milano, Milano, Italy
| | | | | | - Carmelo Drago
- Centro Interdisciplinare Studi bio-molecolari e applicazioni Industriali (CISI), University of Milano, Milano, Italy
| | - Pierfausto Seneci
- Centro Interdisciplinare Studi bio-molecolari e applicazioni Industriali (CISI), University of Milano, Milano, Italy
- Department of Organic and Industrial Chemistry, University of Milano, Milano, Italy
| | - Martino Bolognesi
- Department of Biosciences, University of Milano, Milano, Italy
- CNR-Istituto di Biofisica, Università degli Studi di Milano, Milano, Italy
| | - Eloise Mastrangelo
- Department of Biosciences, University of Milano, Milano, Italy
- CNR-Istituto di Biofisica, Università degli Studi di Milano, Milano, Italy
- * E-mail:
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64
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Yamaguchi N, Yokota M, Taguchi Y, Gohda J, Inoue JI. cIAP1/2 negatively regulate RANKL-induced osteoclastogenesis through the inhibition of NFATc1 expression. Genes Cells 2012; 17:971-81. [PMID: 23126497 DOI: 10.1111/gtc.12012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 09/29/2012] [Indexed: 01/15/2023]
Abstract
Receptor activator of nuclear factor κB (RANK) is a member of the tumor necrosis factor receptor superfamily (TNFRSF) and triggers osteoclastogenesis by inducing the expression of NFATc1 through the activation of the NF-κB and MAPK pathways. Cellular inhibitors of apoptosis proteins 1 and 2 (cIAP1/2), which are ubiquitin E3 ligases, are involved in the activation of the NF-κB and MAPK pathways by various members of the TNFRSF. However, the involvement of cIAP1/2 in RANK signaling has remained largely unknown. In this study, we reveal the involvement of cIAP1/2 in RANK ligand (RANKL)-induced osteoclastogenesis. The over-expression of cIAP1 or cIAP2 in the mouse monocytic cell line Raw264.7 resulted in the significant suppression of RANKL-induced NFATc1 mRNA expression and osteoclastogenesis, whereas the activation of the NF-κB and MAPK pathways was barely changed by these over-expressions. The depletion of endogenous cIAP1/2 by their specific inhibitor MV1 or their siRNA-mediated knockdown resulted in enhanced RANKL-induced NFATc1 expression and osteoclastogenesis without affecting the activation of the NF-κB and MAPK pathways. In combination, these results indicate that cIAP1/2 negatively regulate osteoclastogenesis by inhibiting NFATc1 mRNA expression in a manner that is distinct from the previously identified functions of cIAP1/2.
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Affiliation(s)
- Noritaka Yamaguchi
- Division of Cellular and Molecular Biology, Department of Cancer Biology, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
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65
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The role of the IAP E3 ubiquitin ligases in regulating pattern-recognition receptor signalling. Nat Rev Immunol 2012; 12:833-44. [PMID: 23124073 DOI: 10.1038/nri3325] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
An inflammatory response is initiated when innate immune pattern-recognition receptors (PRRs) expressed by different cell types detect constituents of invading microorganisms and endogenous intracellular molecules released by dying cells. The intracellular cascades activated by PRRs induce the expression and maturation of inflammatory molecules that coordinate the removal of the infectious agents and of the infected or damaged cells. In this Review, we discuss the findings implicating members of the inhibitor of apoptosis protein (IAP) family in the ubiquitylation-dependent regulation of PRR signalling. Understanding the role of IAPs in innate immunity may open new therapeutic perspectives for the treatment of PRR-dependent inflammatory diseases.
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66
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Morizot A, Saleh M. Non-apoptotic functions of cell death effectors in inflammation and innate immunity. Microbes Infect 2012; 14:1241-53. [DOI: 10.1016/j.micinf.2012.06.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Accepted: 06/13/2012] [Indexed: 12/31/2022]
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67
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Marivin A, Berthelet J, Plenchette S, Dubrez L. The Inhibitor of Apoptosis (IAPs) in Adaptive Response to Cellular Stress. Cells 2012; 1:711-37. [PMID: 24710527 PMCID: PMC3901146 DOI: 10.3390/cells1040711] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 09/14/2012] [Accepted: 09/27/2012] [Indexed: 12/31/2022] Open
Abstract
Cells are constantly exposed to endogenous and exogenous cellular injuries. They cope with stressful stimuli by adapting their metabolism and activating various "guardian molecules." These pro-survival factors protect essential cell constituents, prevent cell death, and possibly repair cellular damages. The Inhibitor of Apoptosis (IAPs) proteins display both anti-apoptotic and pro-survival properties and their expression can be induced by a variety of cellular stress such as hypoxia, endoplasmic reticular stress and DNA damage. Thus, IAPs can confer tolerance to cellular stress. This review presents the anti-apoptotic and survival functions of IAPs and their role in the adaptive response to cellular stress. The involvement of IAPs in human physiology and diseases in connection with a breakdown of cellular homeostasis will be discussed.
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Affiliation(s)
- Arthur Marivin
- Institut National de la Santé et de la Recherche Médicale (Inserm), UMR866, Dijon F-21079, France.
| | - Jean Berthelet
- Institut National de la Santé et de la Recherche Médicale (Inserm), UMR866, Dijon F-21079, France.
| | - Stéphanie Plenchette
- Institut Fédératif de Recherche (IFR), Université de Bourgogne, 100, Dijon F-21079, France.
| | - Laurence Dubrez
- Institut National de la Santé et de la Recherche Médicale (Inserm), UMR866, Dijon F-21079, France.
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68
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Duda DM, Olszewski JL, Tron AE, Hammel M, Lambert LJ, Waddell MB, Mittag T, DeCaprio JA, Schulman BA. Structure of a glomulin-RBX1-CUL1 complex: inhibition of a RING E3 ligase through masking of its E2-binding surface. Mol Cell 2012; 47:371-82. [PMID: 22748924 DOI: 10.1016/j.molcel.2012.05.044] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 04/23/2012] [Accepted: 05/17/2012] [Indexed: 10/28/2022]
Abstract
The approximately 300 human cullin-RING ligases (CRLs) are multisubunit E3s in which a RING protein, either RBX1 or RBX2, recruits an E2 to catalyze ubiquitination. RBX1-containing CRLs also can bind Glomulin (GLMN), which binds RBX1's RING domain, regulates the RBX1-CUL1-containing SCF(FBW7) complex, and is disrupted in the disease Glomuvenous Malformation. Here we report the crystal structure of a complex between GLMN, RBX1, and a fragment of CUL1. Structural and biochemical analyses reveal that GLMN adopts a HEAT-like repeat fold that tightly binds the E2-interacting surface of RBX1, inhibiting CRL-mediated chain formation by the E2 CDC34. The structure explains the basis for GLMN's selectivity toward RBX1 over RBX2, and how disease-associated mutations disrupt GLMN-RBX1 interactions. Our study reveals a mechanism for RING E3 ligase regulation, whereby an inhibitor blocks E2 access, and raises the possibility that other E3s are likewise controlled by cellular proteins that mask E2-binding surfaces to mediate inhibition.
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Affiliation(s)
- David M Duda
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis TN 38105, USA
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Koshimizu T, Kawai M, Kondou H, Tachikawa K, Sakai N, Ozono K, Michigami T. Vinculin functions as regulator of chondrogenesis. J Biol Chem 2012; 287:15760-75. [PMID: 22416133 DOI: 10.1074/jbc.m111.308072] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To identify the genes involved in chondrocytic differentiation, we applied gene trap mutagenesis to a murine mesenchymal chondrogenic cell line ATDC5 and isolated a clone in which the gene encoding vinculin was trapped. The trapped allele was assumed to express a fusion protein containing a truncated vinculin lacking the tail domain and the geo product derived from the trap vector. The truncated vinculin was suggested to exert a dominant negative effect. Impaired functioning of vinculin caused by gene trapping in ATDC5 cells or knockdown in primary chondrocytes resulted in the reduced expression of chondrocyte-specific genes, including Col2a1, aggrecan, and Col10a1. The expression of Runx2 also was suppressed by the dysfunctional vinculin. On the other hand, the expression of Sox9, encoding a key transcription factor for chondrogenesis, was retained. Knockdown of vinculin in metatarsal organ cultures impaired the growth of the explants and reduced the expression of Col2a1 and aggrecan. Gene trapping or knockdown of vinculin decreased the phosphorylation of ERK1/2 but increased that of Src homology 2 domain-containing tyrosine phosphatase 2 (SHP2) and Akt during chondrocytic differentiation, suggesting a disturbance of signaling by insulin-like growth factor I (IGF-I). Knockdown of vinculin in the metatarsal organ culture abrogated the IGF-I-induced growth and inhibited the up-regulation of Col2a1 and aggrecan expression by IGF-I. Loss of vinculin function in differentiating chondrocytes impaired the activation of the p38 MAPK pathway also, suggesting its involvement in the regulation of chondrogenesis by vinculin. Our results indicate a tissue-specific function of vinculin in cartilage whereby it controls chondrocytic differentiation.
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Affiliation(s)
- Takao Koshimizu
- Department of Bone and Mineral Research, Osaka Medical Center and Research Institute for Maternal and Child Health, 840 Murodo-cho, Izumi, Osaka 594-1101, Japan
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70
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Labbé K, McIntire CR, Doiron K, Leblanc PM, Saleh M. Cellular inhibitors of apoptosis proteins cIAP1 and cIAP2 are required for efficient caspase-1 activation by the inflammasome. Immunity 2012; 35:897-907. [PMID: 22195745 DOI: 10.1016/j.immuni.2011.10.016] [Citation(s) in RCA: 121] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Revised: 10/05/2011] [Accepted: 10/21/2011] [Indexed: 01/05/2023]
Abstract
Pathogen and danger recognition by the inflammasome activates inflammatory caspases that mediate inflammation and cell death. The cellular inhibitor of apoptosis proteins (cIAPs) function in apoptosis and innate immunity, but their role in modulating the inflammasome and the inflammatory caspases is unknown. Here we report that the cIAPs are critical effectors of the inflammasome and are required for efficient caspase-1 activation. cIAP1, cIAP2, and the adaptor protein TRAF2 interacted with caspase-1-containing complexes and mediated the activating nondegradative K63-linked polyubiquitination of caspase-1. Deficiency in cIAP1 (encoded by Birc2) or cIAP2 (Birc3) impaired caspase-1 activation after spontaneous or agonist-induced inflammasome assembly, and Birc2(-/-) or Birc3(-/-) mice or mice administered with an IAP antagonist had a dampened response to inflammasome agonists and were resistant to peritonitis. Our results describe a role for the cIAPs in innate immunity and further demonstrate the evolutionary conservation between cell death and inflammation mechanisms.
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Affiliation(s)
- Katherine Labbé
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec H3G 0B1, Canada
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71
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Feltham R, Khan N, Silke J. IAPS and ubiquitylation. IUBMB Life 2012; 64:411-8. [DOI: 10.1002/iub.565] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Accepted: 07/25/2011] [Indexed: 11/11/2022]
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72
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Cartier J, Marivin A, Berthelet J, Dubrez L. [IAPs: a central element in the NF-κB activating signaling pathway]. Med Sci (Paris) 2012; 28:69-75. [PMID: 22289833 DOI: 10.1051/medsci/2012281019] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The function of IAP has long been limited to an inhibition of apoptosis through their capacity to bind some caspases. Since the expression of these proteins is altered in some tumor samples, IAPs are targets for anticancer therapy and many small molecules have been designed for their capacity to inhibit IAP-caspase interaction. Unexpectedly, these molecules appeared to significantly affect NF-κB activation. In this review, we will discuss the central role of cIAP1, cIAP2 and XIAP in the regulation of NF-κB activating signaling pathways.
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Affiliation(s)
- Jessy Cartier
- Inserm UMR 866, Faculté de Médecine, Université de Bourgogne, 7, Boulevard Jeanne d'Arc, 21079 Dijon Cedex, France
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73
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Dou H, Buetow L, Hock A, Sibbet GJ, Vousden KH, Huang DT. Structural basis for autoinhibition and phosphorylation-dependent activation of c-Cbl. Nat Struct Mol Biol 2012; 19:184-92. [PMID: 22266821 PMCID: PMC3880865 DOI: 10.1038/nsmb.2231] [Citation(s) in RCA: 141] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2011] [Accepted: 12/19/2011] [Indexed: 12/12/2022]
Abstract
Cbls are RING ubiquitin ligases that attenuate receptor tyrosine kinase (RTK) signal transduction. Cbl ubiquitination activity is stimulated by phosphorylation of a linker helix region (LHR) tyrosine residue. To elucidate the mechanism of activation, we determined the structures of human CBL, a CBL-substrate peptide complex and a phosphorylated-Tyr371-CBL-E2-substrate peptide complex, and we compared them with the known structure of a CBL-E2-substrate peptide complex. Structural and biochemical analyses show that CBL adopts an autoinhibited RING conformation, where the RING's E2-binding surface associates with CBL to reduce E2 affinity. Tyr371 phosphorylation activates CBL by inducing LHR conformational changes that eliminate autoinhibition, flip the RING domain and E2 into proximity of the substrate-binding site and transform the RING domain into an enhanced E2-binding module. This activation is required for RTK ubiquitination. Our results present a mechanism for regulation of c-Cbl's activity by autoinhibition and phosphorylation-induced activation.
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Affiliation(s)
- Hao Dou
- The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Glasgow, G61 1BD, United Kingdom
| | - Lori Buetow
- The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Glasgow, G61 1BD, United Kingdom
| | - Andreas Hock
- The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Glasgow, G61 1BD, United Kingdom
| | - Gary J Sibbet
- The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Glasgow, G61 1BD, United Kingdom
| | - Karen H Vousden
- The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Glasgow, G61 1BD, United Kingdom
| | - Danny T Huang
- The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Glasgow, G61 1BD, United Kingdom
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74
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Ubiquitin-mediated regulation of RhoGTPase signalling: IAPs and HACE1 enter the fray. EMBO J 2012; 31:1-2. [PMID: 22215447 DOI: 10.1038/emboj.2011.452] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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75
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Oberoi TK, Dogan T, Hocking JC, Scholz RP, Mooz J, Anderson CL, Karreman C, Meyer zu Heringdorf D, Schmidt G, Ruonala M, Namikawa K, Harms GS, Carpy A, Macek B, Köster RW, Rajalingam K. IAPs regulate the plasticity of cell migration by directly targeting Rac1 for degradation. EMBO J 2011; 31:14-28. [PMID: 22117219 DOI: 10.1038/emboj.2011.423] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Accepted: 10/28/2011] [Indexed: 11/09/2022] Open
Abstract
Inhibitors of apoptosis proteins (IAPs) are a highly conserved class of multifunctional proteins. Rac1 is a well-studied Rho GTPase that controls numerous basic cellular processes. While the regulation of nucleotide binding to Rac1 is well understood, the molecular mechanisms controlling Rac1 degradation are not known. Here, we demonstrate X-linked IAP (XIAP) and cellular IAP1 (c-IAP1) directly bind to Rac1 in a nucleotide-independent manner to promote its polyubiquitination at Lys147 and proteasomal degradation. These IAPs are also required for degradation of Rac1 upon CNF1 toxin treatment or RhoGDI depletion. Consistently, downregulation of XIAP or c-IAP1 by various strategies led to an increase in Rac1 protein levels in primary and tumour cells, leading to an elongated morphology and enhanced cell migration. Further, XIAP counteracts Rac1-dependent cellular polarization in the developing zebrafish hindbrain and promotes the delamination of neurons from the normal tissue architecture. These observations unveil an evolutionarily conserved role of IAPs in controlling Rac1 stability thereby regulating the plasticity of cell migration and morphogenesis.
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Affiliation(s)
- Tripat Kaur Oberoi
- Emmy Noether Group of the DFG, Institute of Biochemistry II, Goethe University Medical School, Frankfurt, Germany
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76
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Abstract
Deregulation of innate immune signalling and cell death form the basis of most human disease pathogenesis. Inhibitor of APoptosis (IAP) protein-family members are frequently overexpressed in cancer and contribute to tumour cell survival, chemo-resistance, disease progression and poor prognosis. Although best known for their ability to regulate caspases, IAPs also influence ubiquitin-dependent pathways that modulate innate immune signalling by activation of NF-κB. Recent advances in our understanding of the molecular mechanisms through which IAPs influence cell death and innate immune responses have provided new insights into novel strategies for treatment of cancer. In this review we discuss our current understanding of IAP-mediated NF-κB signalling, as well as elaborate on unexpected insights into the involvement of IAPs in regulating the 'Ripoptosome', a novel intrinsic cell death-inducing platform. We propose an evolutionarily conserved concept whereby IAPs function as guardians of killer platforms such as the apoptosome in Drosophila and the Ripoptosome in mammals.
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Affiliation(s)
- M Darding
- The Breakthrough Toby Robins Breast Cancer Research Centre, Institute of Cancer Research, London, UK
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Oetjen KA, Duckett CS. Identifying the trigger of c-IAPs: structural and functional characterization of CARD-mediated modulation of ubiquitin ligase activity. Mol Cell 2011; 42:553-4. [PMID: 21658595 DOI: 10.1016/j.molcel.2011.05.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In this issue of Molecular Cell, Lopez et al. (2011) examine the caspase-recruitment domain (CARD) of c-IAP1 to reveal an intriguing mechanism in which conformational changes of the CARD determine c-IAP1's ubiquitin ligase activity, with implications for regulation of cell proliferation and survival by the IAPs.
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Affiliation(s)
- Karolyn A Oetjen
- Department of Pathology, The University of Michigan Medical School, Ann Arbor, MI 48109, USA
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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: 729] [Impact Index Per Article: 56.1] [Reference Citation Analysis] [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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