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Yang X, Zeng Q, İnam MG, İnam O, Lin CS, Tezel G. cFLIP in the molecular regulation of astroglia-driven neuroinflammation in experimental glaucoma. J Neuroinflammation 2024; 21:145. [PMID: 38824526 PMCID: PMC11143607 DOI: 10.1186/s12974-024-03141-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Accepted: 05/24/2024] [Indexed: 06/03/2024] Open
Abstract
BACKGROUND Recent experimental studies of neuroinflammation in glaucoma pointed to cFLIP as a molecular switch for cell fate decisions, mainly regulating cell type-specific caspase-8 functions in cell death and inflammation. This study aimed to determine the importance of cFLIP for regulating astroglia-driven neuroinflammation in experimental glaucoma by analyzing the outcomes of astroglia-targeted transgenic deletion of cFLIP or cFLIPL. METHODS Glaucoma was modeled by anterior chamber microbead injections to induce ocular hypertension in mouse lines with or without conditional deletion of cFLIP or cFLIPL in astroglia. Morphological analysis of astroglia responses assessed quantitative parameters in retinal whole mounts immunolabeled for GFAP and inflammatory molecules or assayed for TUNEL. The molecular analysis included 36-plexed immunoassays of the retina and optic nerve cytokines and chemokines, NanoString-based profiling of inflammation-related gene expression, and Western blot analysis of selected proteins in freshly isolated samples of astroglia. RESULTS Immunoassays and immunolabeling of retina and optic nerve tissues presented reduced production of various proinflammatory cytokines, including TNFα, in GFAP/cFLIP and GFAP/cFLIPL relative to controls at 12 weeks of ocular hypertension with no detectable alteration in TUNEL. Besides presenting a similar trend of the proinflammatory versus anti-inflammatory molecules displayed by immunoassays, NanoString-based molecular profiling detected downregulated NF-κB/RelA and upregulated RelB expression of astroglia in ocular hypertensive samples of GFAP/cFLIP compared to ocular hypertensive controls. Analysis of protein expression also revealed decreased phospho-RelA and increased phospho-RelB in parallel with an increase in caspase-8 cleavage products. CONCLUSIONS A prominent response limiting neuroinflammation in ocular hypertensive eyes with cFLIP-deletion in astroglia values the role of cFLIP in the molecular regulation of glia-driven neuroinflammation during glaucomatous neurodegeneration. The molecular responses accompanying the lessening of neurodegenerative inflammation also seem to maintain astroglia survival despite increased caspase-8 cleavage with cFLIP deletion. A transcriptional autoregulatory response, dampening RelA but boosting RelB for selective expression of NF-κB target genes, might reinforce cell survival in cFLIP-deleted astroglia.
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Affiliation(s)
- Xiangjun Yang
- Department of Ophthalmology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, 10032, USA
| | - Qun Zeng
- Department of Ophthalmology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, 10032, USA
| | - Maide Gözde İnam
- Department of Ophthalmology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, 10032, USA
| | - Onur İnam
- Department of Ophthalmology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, 10032, USA
| | - Chyuan-Sheng Lin
- Department of Pathology & Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Gülgün Tezel
- Department of Ophthalmology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, 10032, USA.
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2
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Mechanisms of TNF-independent RIPK3-mediated cell death. Biochem J 2022; 479:2049-2062. [PMID: 36240069 DOI: 10.1042/bcj20210724] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 09/16/2022] [Accepted: 09/21/2022] [Indexed: 11/17/2022]
Abstract
Apoptosis and necroptosis regulate many aspects of organismal biology and are involved in various human diseases. TNF is well known to induce both of these forms of cell death and the underlying mechanisms have been elaborately described. However, cells can also engage apoptosis and necroptosis through TNF-independent mechanisms, involving, for example, activation of the pattern recognition receptors Toll-like receptor (TLR)-3 and -4, or zDNA-binding protein 1 (ZBP1). In this context, cell death signaling depends on the presence of receptor-interacting serine/threonine protein kinase 3 (RIPK3). Whereas RIPK3 is required for TNF-induced necroptosis, it mediates both apoptosis and necroptosis upon TLR3/4 and ZBP1 engagement. Here, we review the intricate mechanisms by which TNF-independent cell death is regulated by RIPK3.
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3
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An engineered construct of cFLIP provides insight into DED1 structure and interactions. Structure 2022; 30:229-239.e5. [PMID: 34800372 PMCID: PMC8818036 DOI: 10.1016/j.str.2021.10.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 08/24/2021] [Accepted: 10/22/2021] [Indexed: 02/05/2023]
Abstract
Cellular FLICE-like inhibitory protein (cFLIP) is a member of the Death Domain superfamily with pivotal roles in many cellular processes and disease states, including cancer and autoimmune disorders. In the context of the death-inducing signaling complex (DISC), cFLIP isoforms regulate extrinsic apoptosis by controlling procaspase-8 activation. The function of cFLIP is mediated through a series of protein-protein interactions, engaging the two N-terminal death effector domains (DEDs). Here, we solve the structure of an engineered DED1 domain of cFLIP using solution nuclear magnetic resonance (NMR) and we define the interaction with FADD and calmodulin, protein-protein interactions that regulate the function of cFLIP in the DISC. cFLIP DED1 assumes a canonical DED fold characterized by six α helices and is able to bind calmodulin and FADD through two separate interfaces. Our results clearly demonstrate the role of DED1 in the cFLIP/FADD association and contribute to the understanding of the assembly of DISC filaments.
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4
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Ivanisenko NV, Seyrek K, Hillert-Richter LK, König C, Espe J, Bose K, Lavrik IN. Regulation of extrinsic apoptotic signaling by c-FLIP: towards targeting cancer networks. Trends Cancer 2021; 8:190-209. [PMID: 34973957 DOI: 10.1016/j.trecan.2021.12.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 11/30/2021] [Accepted: 12/01/2021] [Indexed: 02/07/2023]
Abstract
The extrinsic pathway is mediated by death receptors (DRs), including CD95 (APO-1/Fas) or TRAILR-1/2. Defects in apoptosis regulation lead to cancer and other malignancies. The master regulator of the DR networks is the cellular FLICE inhibitory protein (c-FLIP). In addition to its key role in apoptosis, c-FLIP may exert other cellular functions, including control of necroptosis, pyroptosis, nuclear factor κB (NF-κB) activation, and tumorigenesis. To gain further insight into the molecular mechanisms of c-FLIP action in cancer networks, we focus on the structure, isoforms, interactions, and post-translational modifications of c-FLIP. We also discuss various avenues to target c-FLIP in cancer cells for therapeutic benefit.
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Affiliation(s)
- Nikita V Ivanisenko
- The Federal Research Center Institute of Cytology and Genetics SB RAS, Novosibirsk, Russia; Artificial Intelligence Research Institute, Moscow, Russia
| | - Kamil Seyrek
- Translational Inflammation Research, Medical Faculty, Otto von Guericke University Magdeburg, 39106 Magdeburg, Germany
| | - Laura K Hillert-Richter
- Translational Inflammation Research, Medical Faculty, Otto von Guericke University Magdeburg, 39106 Magdeburg, Germany
| | - Corinna König
- Translational Inflammation Research, Medical Faculty, Otto von Guericke University Magdeburg, 39106 Magdeburg, Germany
| | - Johannes Espe
- Translational Inflammation Research, Medical Faculty, Otto von Guericke University Magdeburg, 39106 Magdeburg, Germany
| | - Kakoli Bose
- Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Tata Memorial Centre, Kharghar, Navi Mumbai 410210, India; Homi Bhabha National Institute, BARC Training School Complex, Anushaktinagar, Mumbai 400094, India
| | - Inna N Lavrik
- The Federal Research Center Institute of Cytology and Genetics SB RAS, Novosibirsk, Russia; Translational Inflammation Research, Medical Faculty, Otto von Guericke University Magdeburg, 39106 Magdeburg, Germany.
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5
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Tomaipitinca L, Petrungaro S, D'Acunzo P, Facchiano A, Dubey A, Rizza S, Giulitti F, Gaudio E, Filippini A, Ziparo E, Cecconi F, Giampietri C. c-FLIP regulates autophagy by interacting with Beclin-1 and influencing its stability. Cell Death Dis 2021; 12:686. [PMID: 34238932 PMCID: PMC8266807 DOI: 10.1038/s41419-021-03957-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 06/14/2021] [Accepted: 06/15/2021] [Indexed: 01/18/2023]
Abstract
c-FLIP (cellular FLICE-like inhibitory protein) protein is mostly known as an apoptosis modulator. However, increasing data underline that c-FLIP plays multiple roles in cellular homoeostasis, influencing differently the same pathways depending on its expression level and isoform predominance. Few and controversial data are available regarding c-FLIP function in autophagy. Here we show that autophagic flux is less effective in c-FLIP−/− than in WT MEFs (mouse embryonic fibroblasts). Indeed, we show that the absence of c-FLIP compromises the expression levels of pivotal factors in the generation of autophagosomes. In line with the role of c-FLIP as a scaffold protein, we found that c-FLIPL interacts with Beclin-1 (BECN1: coiled-coil, moesin-like BCL2-interacting protein), which is required for autophagosome nucleation. By a combination of bioinformatics tools and biochemistry assays, we demonstrate that c-FLIPL interaction with Beclin-1 is important to prevent Beclin-1 ubiquitination and degradation through the proteasomal pathway. Taken together, our data describe a novel molecular mechanism through which c-FLIPL positively regulates autophagy, by enhancing Beclin-1 protein stability.
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Affiliation(s)
- Luana Tomaipitinca
- Department of Anatomy, Histology, Forensic Medicine and Orthopedics, Sapienza University of Rome, Rome, Italy.,Cell Stress and Survival Unit, Danish Cancer Society Research Center, Copenhagen, 2100, Denmark
| | - Simonetta Petrungaro
- Department of Anatomy, Histology, Forensic Medicine and Orthopedics, Sapienza University of Rome, Rome, Italy
| | - Pasquale D'Acunzo
- Center for Dementia Research, Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY, 10962, USA.,Department of Psychiatry, New York University School of Medicine, New York, NY, 10016, USA
| | | | - Amit Dubey
- Computational Chemistry and Drug Discovery Division, Quanta Calculus Pvt Ltd, Kushinagar, 274203, India.,Department of Pharmacology, Saveetha Dental College and Hospital, Saveetha Institute of Medical and Technical Sciences, Chennai, Tamil Nadu, India
| | - Salvatore Rizza
- Redox Signaling and Oxidative Stress Group, Danish Cancer Society Research Center, Copenhagen, 2100, Denmark
| | - Federico Giulitti
- Department of Anatomy, Histology, Forensic Medicine and Orthopedics, Sapienza University of Rome, Rome, Italy
| | - Eugenio Gaudio
- Department of Anatomy, Histology, Forensic Medicine and Orthopedics, Sapienza University of Rome, Rome, Italy
| | - Antonio Filippini
- Department of Anatomy, Histology, Forensic Medicine and Orthopedics, Sapienza University of Rome, Rome, Italy.
| | - Elio Ziparo
- Department of Anatomy, Histology, Forensic Medicine and Orthopedics, Sapienza University of Rome, Rome, Italy
| | - Francesco Cecconi
- Cell Stress and Survival Unit, Danish Cancer Society Research Center, Copenhagen, 2100, Denmark.,Department of Pediatric Hemato-Oncology and Cell and Gene therapy, IRCCS Bambino Gesù Children's Hospital, Rome, 00143, Italy.,Department of Biology, University of Tor Vergata, Rome, 00133, Italy
| | - Claudia Giampietri
- Department of Anatomy, Histology, Forensic Medicine and Orthopedics, Sapienza University of Rome, Rome, Italy.
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6
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Regulation of distinct caspase-8 functions in retinal ganglion cells and astroglia in experimental glaucoma. Neurobiol Dis 2021; 150:105258. [PMID: 33434617 DOI: 10.1016/j.nbd.2021.105258] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 12/30/2020] [Accepted: 01/07/2021] [Indexed: 12/13/2022] Open
Abstract
Retinal ganglion cells (RGCs) expanding from the retina to the brain are primary victims of neurodegeneration in glaucoma, a leading cause of blindness; however, the neighboring astroglia survive the glaucoma-related stress and promote neuroinflammation. In light of diverse functions of caspase-8 in apoptosis, cell survival, and inflammation, this study investigated the importance of caspase-8 in different fates of glaucomatous RGCs and astroglia using two experimental approaches in parallel. In the first approach, cell type-specific responses of RGCs and astroglia to a caspase-8 cleavage-inhibiting pharmacological treatment were studied in rat eyes with or without experimentally induced glaucoma. The second approach utilized an experimental model of glaucoma in mice in which astroglial caspase-8 was conditionally deleted by cre/lox. Findings of these experiments revealed cell type-specific distinct processes that regulate caspase-8 functions in experimental glaucoma, which are involved in inducing the apoptosis of RGCs and promoting the survival and inflammatory responses of astroglia. Deletion of caspase-8 in astroglia protected RGCs against glia-driven inflammatory injury, while the inhibition of caspase-8 cleavage inhibited apoptosis in RGCs themselves. Various caspase-8 functions impacting both RGC apoptosis and astroglia-driven neuroinflammation may suggest the multi-target potential of caspase-8 regulation to provide neuroprotection and immunomodulation in glaucoma.
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7
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Ivanisenko NV, Lavrik IN. Mathematical Modeling Reveals the Importance of the DED Filament Composition in the Effects of Small Molecules Targeting Caspase-8/c-FLIP L Heterodimer. BIOCHEMISTRY (MOSCOW) 2020; 85:1134-1144. [PMID: 33202199 DOI: 10.1134/s0006297920100028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Procaspase-8 activation at the death-inducing signaling complex (DISC) triggers extrinsic apoptotic pathway. Procaspase-8 activation takes place in the death effector domain (DED) filaments and is regulated by c-FLIP proteins, in particular, by the long isoform c-FLIPL. Recently, the first-in-class chemical probe targeting the caspase-8/c-FLIPL heterodimer was reported. This rationally designed small molecule, FLIPin, enhances caspase-8 activity after initial heterodimer processing. Here, we used a kinetic mathematical model to gain an insight into the mechanisms of FLIPin action in a complex with DISC, in particular, to unravel the effects of FLIPin at different stoichiometry and composition of the DED filament. Analysis of this model has identified the optimal c-FLIPL to procaspase-8 ratios in different cellular landscapes favoring the activity of FLIPin. We predicted that the activity FLIPin is regulated via different mechanisms upon c-FLIPL downregulation or upregulation. Our study demonstrates that a combination of mathematical modeling with system pharmacology allows development of more efficient therapeutic approaches and prediction of optimal treatment strategies.
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Affiliation(s)
- N V Ivanisenko
- Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia.
| | - I N Lavrik
- Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia. .,Translational Inflammation Research, Medical Faculty, Otto von Guericke University Magdeburg, Magdeburg, 39106, Germany
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8
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Orning P, Lien E. Multiple roles of caspase-8 in cell death, inflammation, and innate immunity. J Leukoc Biol 2020; 109:121-141. [PMID: 32531842 DOI: 10.1002/jlb.3mr0420-305r] [Citation(s) in RCA: 82] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 04/16/2020] [Accepted: 04/30/2020] [Indexed: 12/20/2022] Open
Abstract
Caspase-8 is an apical caspase involved in the programmed form of cell death called apoptosis that is critically important for mammalian development and immunity. Apoptosis was historically described as immunologically silent in contrast to other types of programmed cell death such as necroptosis or pyroptosis. Recent reports suggest considerable crosstalk between these different forms of cell death. It is becoming increasingly clear that caspase-8 has many non-apoptotic roles, participating in multiple processes including regulation of necroptosis (mediated by receptor-interacting serine/threonine kinases, RIPK1-RIPK3), inflammatory cytokine expression, inflammasome activation, and cleavage of IL-1β and gasdermin D, and protection against shock and microbial infection. In this review, we discuss the involvement of caspase-8 in cell death and inflammation and highlight its role in innate immune responses and in the relationship between different forms of cell death. Caspase-8 is one of the central components in this type of crosstalk.
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Affiliation(s)
- Pontus Orning
- UMass Medical School, Program in Innate Immunity, Division of Infectious Diseases and Immunology, Department of Medicine, Worcester, Massachusetts, USA.,Centre of Molecular Inflammation Research, Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Egil Lien
- UMass Medical School, Program in Innate Immunity, Division of Infectious Diseases and Immunology, Department of Medicine, Worcester, Massachusetts, USA.,Centre of Molecular Inflammation Research, Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
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9
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c-FLIP is crucial for IL-7/IL-15-dependent NKp46 + ILC development and protection from intestinal inflammation in mice. Nat Commun 2020; 11:1056. [PMID: 32103006 PMCID: PMC7044440 DOI: 10.1038/s41467-020-14782-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 01/24/2020] [Indexed: 12/18/2022] Open
Abstract
NKp46+ innate lymphoid cells (ILC) modulate tissue homeostasis and anti-microbial immune responses. ILC development and function are regulated by cytokines such as Interleukin (IL)-7 and IL-15. However, the ILC-intrinsic pathways translating cytokine signals into developmental programs are largely unknown. Here we show that the anti-apoptotic molecule cellular FLICE-like inhibitory protein (c-FLIP) is crucial for the generation of IL-7/IL-15-dependent NKp46+ ILC1, including conventional natural killer (cNK) cells, and ILC3. Cytokine-induced phosphorylation of signal transducer and activator of transcription 5 (STAT5) precedes up-regulation of c-FLIP, which protects developing NKp46+ ILC from TNF-induced apoptosis. NKp46+ ILC-specific inactivation of c-FLIP leads to the loss of all IL-7/IL-15-dependent NKp46+ ILC, thereby inducing early-onset chronic colitis and subsequently microbial dysbiosis; meanwhile, the depletion of cNK, but not NKp46+ ILC1/3, aggravates experimental colitis. In summary, our data demonstrate a non-redundant function of c-FLIP for the generation of NKp46+ ILC, which protect T/B lymphocyte-sufficient mice from intestinal inflammation.
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10
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Long and short isoforms of c-FLIP act as control checkpoints of DED filament assembly. Oncogene 2019; 39:1756-1772. [PMID: 31740779 DOI: 10.1038/s41388-019-1100-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Revised: 11/02/2019] [Accepted: 11/04/2019] [Indexed: 12/31/2022]
Abstract
The assembly of the death-inducing signaling complex (DISC) and death effector domain (DED) filaments at CD95/Fas initiates extrinsic apoptosis. Procaspase-8 activation at the DED filaments is controlled by short and long c-FLIP isoforms. Despite apparent progress in understanding the assembly of CD95-activated platforms and DED filaments, the detailed molecular mechanism of c-FLIP action remains elusive. Here, we further addressed the mechanisms of c-FLIP action at the DISC using biochemical assays, quantitative mass spectrometry, and structural modeling. Our data strongly indicate that c-FLIP can bind to both FADD and procaspase-8 at the DED filament. Moreover, the constructed in silico model shows that c-FLIP proteins can lead to the formation of the DISCs comprising short DED filaments as well as serve as bridging motifs for building a cooperative DISC network, in which adjacent CD95 DISCs are connected by DED filaments. This network is based on selective interactions of FADD with both c-FLIP and procaspase-8. Hence, c-FLIP proteins at the DISC control initiation, elongation, and composition of DED filaments, playing the role of control checkpoints. These findings provide new insights into DISC and DED filament regulation and open innovative possibilities for targeting the extrinsic apoptosis pathway.
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11
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Guégan JP, Ginestier C, Charafe-Jauffret E, Ducret T, Quignard JF, Vacher P, Legembre P. CD95/Fas and metastatic disease: What does not kill you makes you stronger. Semin Cancer Biol 2019; 60:121-131. [PMID: 31176682 DOI: 10.1016/j.semcancer.2019.06.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 06/05/2019] [Accepted: 06/05/2019] [Indexed: 12/14/2022]
Abstract
CD95 (also known as Fas) is the prototype of death receptors; however, evidence suggests that this receptor mainly implements non-apoptotic signaling pathways such as NF-κB, MAPK, and PI3K that are involved in cell migration, differentiation, survival, and cytokine secretion. At least two different forms of CD95 L exist. The multi-aggregated transmembrane ligand (m-CD95 L) is cleaved by metalloproteases to release a homotrimeric soluble ligand (s-CD95 L). Unlike m-CD95 L, the interaction between s-CD95 L and its receptor CD95 fails to trigger apoptosis, but instead promotes calcium-dependent cell migration, which contributes to the accumulation of inflammatory Th17 cells in damaged organs of lupus patients and favors cancer cell invasiveness. Novel inhibitors targeting the pro-inflammatory roles of CD95/CD95 L may provide attractive therapeutic options for patients with chronic inflammatory disorders or cancer. This review discusses the roles of the CD95/CD95 L pair in cell migration and metastasis.
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Affiliation(s)
- Jean Philippe Guégan
- CLCC Eugène Marquis, Équipe Ligue Contre Le Cancer, Rennes, France; Université Rennes, INSERM U1242, Rennes, France
| | - Christophe Ginestier
- Aix-Marseille Univ, Inserm, CNRS, Institut Paoli-Calmettes, CRCM, Epithelial Stem Cells and Cancer Lab, Marseille, France
| | - Emmanuelle Charafe-Jauffret
- Aix-Marseille Univ, Inserm, CNRS, Institut Paoli-Calmettes, CRCM, Epithelial Stem Cells and Cancer Lab, Marseille, France
| | - Thomas Ducret
- Université de Bordeaux, Bordeaux, France; Centre de Recherche Cardio Thoracique de Bordeaux, INSERM U1045, Bordeaux, France
| | - Jean-François Quignard
- Université de Bordeaux, Bordeaux, France; Centre de Recherche Cardio Thoracique de Bordeaux, INSERM U1045, Bordeaux, France
| | - Pierre Vacher
- Université de Bordeaux, Bordeaux, France; INSERM U1218, Bordeaux, France
| | - Patrick Legembre
- CLCC Eugène Marquis, Équipe Ligue Contre Le Cancer, Rennes, France; Université Rennes, INSERM U1242, Rennes, France.
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12
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Luebke T, Schwarz L, Beer YY, Schumann S, Misterek M, Sander FE, Plaza-Sirvent C, Schmitz I. c-FLIP and CD95 signaling are essential for survival of renal cell carcinoma. Cell Death Dis 2019; 10:384. [PMID: 31097685 PMCID: PMC6522538 DOI: 10.1038/s41419-019-1609-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 04/24/2019] [Indexed: 12/18/2022]
Abstract
Clear cell renal cell carcinoma (ccRCC) is the most-prominent tumor type of kidney cancers. Resistance of renal cell carcinoma (RCC) against tumor therapy is often owing to apoptosis resistance, e.g., by overexpression of anti-apoptotic proteins. However, little is known about the role of the apoptosis inhibitor c-FLIP and its potential impact on death receptor-induced apoptosis in ccRCC cells. In this study, we demonstrate that c-FLIP is crucial for resistance against CD95L-induced apoptosis in four ccRCC cell lines. Strikingly, downregulation of c-FLIP expression by short hairpin RNA (shRNA)interference led to spontaneous caspase activation and apoptotic cell death. Of note, knockdown of all c-FLIP splice variants was required to induce apoptosis. Stimulation of ccRCC cells with CD95L induced NF-κB and MAP kinase survival pathways as revealed by phosphorylation of RelA/p65 and Erk1/2. Interestingly, CD95L surface expression was high in all cell lines analyzed, and CD95 but not TNF-R1 clustered at cell contact sites. Downstream of CD95, inhibition of the NF-κB pathway led to spontaneous cell death. Surprisingly, knockdown experiments revealed that c-FLIP inhibits NF-κB activation in the context of CD95 signaling. Thus, c-FLIP inhibits apoptosis and dampens NF-κB downstream of CD95 but allows NF-κB activation to a level sufficient for ccRCC cell survival. In summary, we demonstrate a complex CD95-FLIP-NF-κB-signaling circuit, in which CD95-CD95L interactions mediate a paracrine survival signal in ccRCC cells with c-FLIP and NF-κB both being required for inhibiting cell death and ensuring survival. Our findings might lead to novel therapeutic approaches of RCC by circumventing apoptosis resistance.
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Affiliation(s)
- Tobias Luebke
- Institute of Molecular and Clinical Immunology, Otto-von-Guericke University, Leipziger Straße 44, 39120, Magdeburg, Germany
| | - Lisa Schwarz
- Institute of Molecular and Clinical Immunology, Otto-von-Guericke University, Leipziger Straße 44, 39120, Magdeburg, Germany
| | - Yan Yan Beer
- Systems-Oriented Immunology and Inflammation Research Group, Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124, Braunschweig, Germany
| | - Sabrina Schumann
- Institute of Molecular and Clinical Immunology, Otto-von-Guericke University, Leipziger Straße 44, 39120, Magdeburg, Germany
| | - Maria Misterek
- Institute of Molecular and Clinical Immunology, Otto-von-Guericke University, Leipziger Straße 44, 39120, Magdeburg, Germany
| | - Frida Ewald Sander
- Institute of Molecular and Clinical Immunology, Otto-von-Guericke University, Leipziger Straße 44, 39120, Magdeburg, Germany
| | - Carlos Plaza-Sirvent
- Institute of Molecular and Clinical Immunology, Otto-von-Guericke University, Leipziger Straße 44, 39120, Magdeburg, Germany
| | - Ingo Schmitz
- Institute of Molecular and Clinical Immunology, Otto-von-Guericke University, Leipziger Straße 44, 39120, Magdeburg, Germany. .,Systems-Oriented Immunology and Inflammation Research Group, Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124, Braunschweig, Germany.
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13
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Safa AR, Kamocki K, Saadatzadeh MR, Bijangi-Vishehsaraei K. c-FLIP, a Novel Biomarker for Cancer Prognosis, Immunosuppression, Alzheimer's Disease, Chronic Obstructive Pulmonary Disease (COPD), and a Rationale Therapeutic Target. BIOMARKERS JOURNAL 2019; 5:4. [PMID: 32352084 PMCID: PMC7189798 DOI: 10.36648/2472-1646.5.1.59] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Dysregulation of c-FLIP (cellular FADD-like IL-1β-converting enzyme inhibitory protein) has been shown in several diseases including cancer, Alzheimer's disease, and chronic obstructive pulmonary disease (COPD). c-FLIP is a critical anti-cell death protein often overexpressed in tumors and hematological malignancies and its increased expression is often associated with a poor prognosis. c-FLIP frequently exists as long (c-FLIPL) and short (c-FLIPS) isoforms, regulates its anti-cell death functions through binding to FADD (FAS associated death domain protein), an adaptor protein known to activate caspases-8 and -10 and links c-FLIP to several cell death regulating complexes including the death-inducing signaling complex (DISC) formed by various death receptors. c-FLIP also plays a critical role in necroptosis and autophagy. Furthermore, c-FLIP is able to activate several pathways involved in cytoprotection, proliferation, and survival of cancer cells through various critical signaling proteins. Additionally, c-FLIP can inhibit cell death induced by several chemotherapeutics, anti-cancer small molecule inhibitors, and ionizing radiation. Moreover, c-FLIP plays major roles in aiding the survival of immunosuppressive tumor-promoting immune cells and functions in inflammation, Alzheimer's disease (AD), and chronic obstructive pulmonary disease (COPD). Therefore, c-FLIP can serve as a versatile biomarker for cancer prognosis, a diagnostic marker for several diseases, and an effective therapeutic target. In this article, we review the functions of c-FLIP as an anti-apoptotic protein and negative prognostic factor in human cancers, and its roles in resistance to anticancer drugs, necroptosis and autophagy, immunosuppression, Alzheimer's disease, and COPD.
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Affiliation(s)
- Ahmad R Safa
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, USA
| | - Krzysztof Kamocki
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, USA
| | - M Reza Saadatzadeh
- Department of Neurosurgery, Indiana University School of Medicine, Indianapolis, USA
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14
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Schuster M, Moeller M, Bornemann L, Bessen C, Sobczak C, Schmitz S, Witjes L, Kruithoff K, Kohn C, Just O, Kündgen A, Pundt N, Pelzer B, Ampe C, Van Troys M, Nusch A, Haas R, Germing U, Martens L, Jöckel KH, Gunzer M. Surveillance of Myelodysplastic Syndrome via Migration Analyses of Blood Neutrophils: A Potential Prognostic Tool. THE JOURNAL OF IMMUNOLOGY 2018; 201:3546-3557. [PMID: 30446567 DOI: 10.4049/jimmunol.1801071] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 10/16/2018] [Indexed: 11/19/2022]
Abstract
Autonomous migration is a central characteristic of immune cells, and changes in this function have been correlated to the progression and severity of diseases. Hence, the identification of pathologically altered leukocyte migration patterns might be a promising approach for disease surveillance and prognostic scoring. However, because of the lack of standardized and robust assays, migration patterns have not been clinically exploited so far. In this study, we introduce an easy-to-use and cross-laboratory, standardized two-dimensional migration assay for neutrophil granulocytes from peripheral blood. By combining time-lapse video microscopy and automated cell tracking, we calculated the average migration of neutrophils from 111 individual participants of the German Heinz Nixdorf Recall MultiGeneration study under steady-state, formyl-methionyl-leucyl-phenylalanine-, CXCL1-, and CXCL8-stimulated conditions. Comparable values were obtained in an independent laboratory from a cohort in Belgium, demonstrating the robustness and transferability of the assay. In a double-blinded retrospective clinical analysis, we found that neutrophil migration strongly correlated with the Revised International Prognostic Scoring System scoring and risk category of myelodysplastic syndrome (MDS) patients. In fact, patients suffering from high-risk subtypes MDS with excess blasts I or II displayed highly significantly reduced neutrophil migration. Hence, the determination of neutrophil migration patterns might represent a useful tool in the surveillance of MDS. Taken together, we suggest that standardized migration assays of neutrophils and other leukocyte subtypes might be broadly applicable as prognostic and surveillance tools for MDS and potentially for other diseases.
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Affiliation(s)
- Marc Schuster
- Institute for Experimental Immunology and Imaging, University Hospital, University Duisburg-Essen, 45147 Essen, Germany
| | - Mischa Moeller
- Department of Hematology, Oncology and Clinical Immunology, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Lea Bornemann
- Institute for Experimental Immunology and Imaging, University Hospital, University Duisburg-Essen, 45147 Essen, Germany
| | - Clara Bessen
- Institute for Experimental Immunology and Imaging, University Hospital, University Duisburg-Essen, 45147 Essen, Germany
| | - Charlyn Sobczak
- Institute for Experimental Immunology and Imaging, University Hospital, University Duisburg-Essen, 45147 Essen, Germany
| | - Saskia Schmitz
- Institute for Experimental Immunology and Imaging, University Hospital, University Duisburg-Essen, 45147 Essen, Germany
| | - Laura Witjes
- Department of Biochemistry, Ghent University, 9000 Ghent, Belgium
| | - Katja Kruithoff
- Institute for Experimental Immunology and Imaging, University Hospital, University Duisburg-Essen, 45147 Essen, Germany
| | - Christina Kohn
- Institute for Experimental Immunology and Imaging, University Hospital, University Duisburg-Essen, 45147 Essen, Germany
| | - Olga Just
- Institute for Experimental Immunology and Imaging, University Hospital, University Duisburg-Essen, 45147 Essen, Germany
| | - Andrea Kündgen
- Department of Hematology, Oncology and Clinical Immunology, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Noreen Pundt
- Institute for Medical Informatics, Biometry and Epidemiology, University Hospital, University Duisburg-Essen, 45147 Essen, Germany
| | - Benedikt Pelzer
- Institute for Experimental Immunology and Imaging, University Hospital, University Duisburg-Essen, 45147 Essen, Germany
| | - Christophe Ampe
- Department of Biochemistry, Ghent University, 9000 Ghent, Belgium
| | | | - Arnd Nusch
- Onkologische Praxis Velbert, 40822 Mettmann, Germany; and
| | - Rainer Haas
- Department of Hematology, Oncology and Clinical Immunology, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Ulrich Germing
- Department of Hematology, Oncology and Clinical Immunology, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Lennart Martens
- Department of Biochemistry, Ghent University, 9000 Ghent, Belgium.,VIB-UGent Center for Medical Biotechnology, Ghent University, 9000 Ghent, Belgium
| | - Karl-Heinz Jöckel
- Institute for Medical Informatics, Biometry and Epidemiology, University Hospital, University Duisburg-Essen, 45147 Essen, Germany
| | - Matthias Gunzer
- Institute for Experimental Immunology and Imaging, University Hospital, University Duisburg-Essen, 45147 Essen, Germany;
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15
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Humphreys L, Espona-Fiedler M, Longley DB. FLIP as a therapeutic target in cancer. FEBS J 2018; 285:4104-4123. [PMID: 29806737 DOI: 10.1111/febs.14523] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 05/11/2018] [Accepted: 05/24/2018] [Indexed: 12/13/2022]
Abstract
One of the classic hallmarks of cancer is disruption of cell death signalling. Inhibition of cell death promotes tumour growth and metastasis, causes resistance to chemo- and radiotherapies as well as targeted agents, and is frequently due to overexpression of antiapoptotic proteins rather than loss of pro-apoptotic effectors. FLIP is a major apoptosis-regulatory protein frequently overexpressed in solid and haematological cancers, in which its high expression is often correlated with poor prognosis. FLIP, which is expressed as long (FLIP(L)) and short (FLIP(S)) splice forms, achieves its cell death regulatory functions by binding to FADD, a critical adaptor protein which links FLIP to the apical caspase in the extrinsic apoptotic pathway, caspase-8, in a number of cell death regulating complexes, such as the death-inducing signalling complexes (DISCs) formed by death receptors. FLIP also plays a key role (together with caspase-8) in regulating another form of cell death termed programmed necrosis or 'necroptosis', as well as in other key cellular processes that impact cell survival, including autophagy. In addition, FLIP impacts activation of the intrinsic mitochondrial-mediated apoptotic pathway by regulating caspase-8-mediated activation of the pro-apoptotic Bcl-2 family member Bid. It has been demonstrated that FLIP can not only inhibit death receptor-mediated apoptosis, but also cell death induced by a range of clinically relevant chemotherapeutic and targeted agents as well as ionizing radiation. More recently, key roles for FLIP in promoting the survival of immunosuppressive tumour-promoting immune cells have been discovered. Thus, FLIP is of significant interest as an anticancer therapeutic target. In this article, we review FLIP's biology and potential ways of targeting this important tumour and immune cell death regulator.
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Affiliation(s)
- Luke Humphreys
- Drug Resistance Group, Centre for Cancer Research & Cell Biology, Queen's University Belfast, Belfast, UK
| | - Margarita Espona-Fiedler
- Drug Resistance Group, Centre for Cancer Research & Cell Biology, Queen's University Belfast, Belfast, UK
| | - Daniel B Longley
- Drug Resistance Group, Centre for Cancer Research & Cell Biology, Queen's University Belfast, Belfast, UK
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16
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Alimbetov D, Askarova S, Umbayev B, Davis T, Kipling D. Pharmacological Targeting of Cell Cycle, Apoptotic and Cell Adhesion Signaling Pathways Implicated in Chemoresistance of Cancer Cells. Int J Mol Sci 2018; 19:ijms19061690. [PMID: 29882812 PMCID: PMC6032165 DOI: 10.3390/ijms19061690] [Citation(s) in RCA: 96] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 05/31/2018] [Accepted: 06/01/2018] [Indexed: 12/11/2022] Open
Abstract
Chemotherapeutic drugs target a physiological differentiating feature of cancer cells as they tend to actively proliferate more than normal cells. They have well-known side-effects resulting from the death of highly proliferative normal cells in the gut and immune system. Cancer treatment has changed dramatically over the years owing to rapid advances in oncology research. Developments in cancer therapies, namely surgery, radiotherapy, cytotoxic chemotherapy and selective treatment methods due to better understanding of tumor characteristics, have significantly increased cancer survival. However, many chemotherapeutic regimes still fail, with 90% of the drug failures in metastatic cancer treatment due to chemoresistance, as cancer cells eventually develop resistance to chemotherapeutic drugs. Chemoresistance is caused through genetic mutations in various proteins involved in cellular mechanisms such as cell cycle, apoptosis and cell adhesion, and targeting those mechanisms could improve outcomes of cancer therapy. Recent developments in cancer treatment are focused on combination therapy, whereby cells are sensitized to chemotherapeutic agents using inhibitors of target pathways inducing chemoresistance thus, hopefully, overcoming the problems of drug resistance. In this review, we discuss the role of cell cycle, apoptosis and cell adhesion in cancer chemoresistance mechanisms, possible drugs to target these pathways and, thus, novel therapeutic approaches for cancer treatment.
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Affiliation(s)
- Dauren Alimbetov
- Laboratory of bioengineering and regenerative medicine, Center for Life Sciences, National Laboratory Astana, Nazarbayev University, 53 Kabanbay Batyr Ave, Z05H0P9 Astana, Kazakhstan.
| | - Sholpan Askarova
- Laboratory of bioengineering and regenerative medicine, Center for Life Sciences, National Laboratory Astana, Nazarbayev University, 53 Kabanbay Batyr Ave, Z05H0P9 Astana, Kazakhstan.
| | - Bauyrzhan Umbayev
- Laboratory of bioengineering and regenerative medicine, Center for Life Sciences, National Laboratory Astana, Nazarbayev University, 53 Kabanbay Batyr Ave, Z05H0P9 Astana, Kazakhstan.
| | - Terence Davis
- Division of Cancer and Genetics, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK.
| | - David Kipling
- Division of Cancer and Genetics, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK.
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17
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c-FLIP Expression in Foxp3-Expressing Cells Is Essential for Survival of Regulatory T Cells and Prevention of Autoimmunity. Cell Rep 2017; 18:12-22. [DOI: 10.1016/j.celrep.2016.12.022] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 10/21/2016] [Accepted: 12/07/2016] [Indexed: 12/13/2022] Open
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18
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Gates LT, Shisler JL. cFLIPL Interrupts IRF3-CBP-DNA Interactions To Inhibit IRF3-Driven Transcription. THE JOURNAL OF IMMUNOLOGY 2016; 197:923-33. [PMID: 27342840 DOI: 10.4049/jimmunol.1502611] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 05/26/2016] [Indexed: 12/17/2022]
Abstract
Type I IFN induction is critical for antiviral and anticancer defenses. Proper downregulation of type I IFN is equally important to avoid deleterious imbalances in the immune response. The cellular FLIP long isoform protein (cFLIPL) controls type I IFN production, but opposing publications show it as either an inhibitor or inducer of type I IFN synthesis. Regardless, the mechanistic basis for cFLIPL regulation is unknown. Because cFLIPL is important in immune cell development and proliferation, and is a target for cancer therapies, it is important to identify how cFLIPL regulates type I IFN production. Data in this study show that cFLIPL inhibits IFN regulatory factor 3 (IRF3), a transcription factor central for IFN-β and IFN-stimulated gene expression. This inhibition occurs during virus infection, cellular exposure to polyinosinic-polycytidylic acid, or TBK1 overexpression. This inhibition is independent of capase-8 activity. cFLIPL binds to IRF3 and disrupts IRF3 interaction with its IFN-β promoter and its coactivator protein (CREB-binding protein). Mutational analyses reveal that cFLIPL nuclear localization is necessary and sufficient for inhibitory function. This suggests that nuclear cFLIPL prevents IRF3 enhanceosome formation. Unlike other cellular IRF3 inhibitors, cFLIPL did not degrade or dephosphorylate IRF3. Thus, cFLIPL represents a different cellular strategy to inhibit type I IFN production. This new cFLIPL function must be considered to accurately understand how cFLIPL affects immune system development and regulation.
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Affiliation(s)
- Lauren T Gates
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Joanna L Shisler
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
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19
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Baratchian M, Davis CA, Shimizu A, Escors D, Bagnéris C, Barrett T, Collins MK. Distinct Activation Mechanisms of NF-κB Regulator Inhibitor of NF-κB Kinase (IKK) by Isoforms of the Cell Death Regulator Cellular FLICE-like Inhibitory Protein (cFLIP). J Biol Chem 2016; 291:7608-20. [PMID: 26865630 PMCID: PMC4817188 DOI: 10.1074/jbc.m116.718122] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Indexed: 11/06/2022] Open
Abstract
The viral FLICE-like inhibitory protein (FLIP) protein from Kaposi sarcoma-associated herpesvirus activates the NF-κB pathway by forming a stable complex with a central region (amino acids 150-272) of the inhibitor of NF-κB kinase (IKK) γ subunits, thereby activating IKK. Cellular FLIP (cFLIP) forms are also known to activate the NF-κB pathway via IKK activation. Here we demonstrate that cFLIPL, cFLIPS, and their proteolytic product p22-FLIP all require the C-terminal region of NEMO/IKKγ (amino acids 272-419) and its ubiquitin binding function for activation of the IKK kinase (or kinase complex), but none form a stable complex with IKKγ. Our results further reveal that cFLIPLrequires the linear ubiquitin chain assembly complex and the kinase TAK1 for activation of the IKK kinase. Similarly, cFLIPSand p22-FLIP also require TAK1 but do not require LUBAC. In contrast, these isoforms are both components of complexes that incorporate Fas-associated death domain and RIP1, which appear essential for kinase activation. This conservation of IKK activation among the cFLIP family using different mechanisms suggests that the mechanism plays a critical role in their function.
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Affiliation(s)
- Mehdi Baratchian
- From the Medical Research Council Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London, London WC1E 6BT, United Kingdom, Division of Advanced Therapies, National Institute of Biological Standards and Control, Blanche Lane, South Mimms, Potters Bar, Herts EN6 3QG, United Kingdom, and
| | - Christopher A Davis
- From the Medical Research Council Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London, London WC1E 6BT, United Kingdom
| | - Akira Shimizu
- From the Medical Research Council Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London, London WC1E 6BT, United Kingdom
| | - David Escors
- From the Medical Research Council Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London, London WC1E 6BT, United Kingdom
| | - Claire Bagnéris
- Institute of Structural and Molecular Biology, School of Biological Sciences, Birkbeck College, Malet Street, London WC1E 7HX, United Kingdom
| | - Tracey Barrett
- Institute of Structural and Molecular Biology, School of Biological Sciences, Birkbeck College, Malet Street, London WC1E 7HX, United Kingdom
| | - Mary K Collins
- From the Medical Research Council Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London, London WC1E 6BT, United Kingdom, Division of Advanced Therapies, National Institute of Biological Standards and Control, Blanche Lane, South Mimms, Potters Bar, Herts EN6 3QG, United Kingdom, and
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20
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Balance between short and long isoforms of cFLIP regulates Fas-mediated apoptosis in vivo. Proc Natl Acad Sci U S A 2016; 113:1606-11. [PMID: 26798068 DOI: 10.1073/pnas.1517562113] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
cFLIP, an inhibitor of apoptosis, is a crucial regulator of cellular death by apoptosis and necroptosis; its importance in development is exemplified by the embryonic lethality in cFLIP-deficient animals. A homolog of caspase 8 (CASP8), cFLIP exists in two main isoforms: cFLIPL (long) and cFLIPR (short). Although both splice variants regulate death receptor (DR)-induced apoptosis by CASP8, the specific role of each isoform is poorly understood. Here, we report a previously unidentified model of resistance to Fas receptor-mediated liver failure in the wild-derived MSM strain, compared with susceptibility in C57BL/6 (B6) mice. Linkage analysis in F2 intercross (B6 x MSM) progeny identified several MSM loci controlling resistance to Fas-mediated death, including the caspase 8- and FADD-like apoptosis regulator (Cflar) locus encoding cFLIP. Furthermore, we identified a 21-bp insertion in the 3' UTR of the fifth exon of Cflar in MSM that influences differential splicing of cFLIP mRNA. Intriguingly, we observed that MSM liver cells predominantly express the FLIPL variant, in contrast to B6 liver cells, which have higher levels of cFLIPR. In keeping with this finding, genome-wide RNA sequencing revealed a relative abundance of FLIPL transcripts in MSM hepatocytes whereas B6 liver cells had significantly more FLIPR mRNA. Importantly, we show that, in the MSM liver, CASP8 is present exclusively as its cleaved p43 product, bound to cFLIPL. Because of partial enzymatic activity of the heterodimer, it might prevent necroptosis. On the other hand, it prevents cleavage of CASP8 to p10/20 necessary for cleavage of caspase 3 and, thus, apoptosis induction. Therefore, MSM hepatocytes are predisposed for protection from DR-mediated cell death.
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21
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Tsuchiya Y, Nakabayashi O, Nakano H. FLIP the Switch: Regulation of Apoptosis and Necroptosis by cFLIP. Int J Mol Sci 2015; 16:30321-41. [PMID: 26694384 PMCID: PMC4691174 DOI: 10.3390/ijms161226232] [Citation(s) in RCA: 106] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 12/09/2015] [Accepted: 12/11/2015] [Indexed: 12/11/2022] Open
Abstract
cFLIP (cellular FLICE-like inhibitory protein) is structurally related to caspase-8 but lacks proteolytic activity due to multiple amino acid substitutions of catalytically important residues. cFLIP protein is evolutionarily conserved and expressed as three functionally different isoforms in humans (cFLIPL, cFLIPS, and cFLIPR). cFLIP controls not only the classical death receptor-mediated extrinsic apoptosis pathway, but also the non-conventional pattern recognition receptor-dependent apoptotic pathway. In addition, cFLIP regulates the formation of the death receptor-independent apoptotic platform named the ripoptosome. Moreover, recent studies have revealed that cFLIP is also involved in a non-apoptotic cell death pathway known as programmed necrosis or necroptosis. These functions of cFLIP are strictly controlled in an isoform-, concentration- and tissue-specific manner, and the ubiquitin-proteasome system plays an important role in regulating the stability of cFLIP. In this review, we summarize the current scientific findings from biochemical analyses, cell biological studies, mathematical modeling, and gene-manipulated mice models to illustrate the critical role of cFLIP as a switch to determine the destiny of cells among survival, apoptosis, and necroptosis.
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Affiliation(s)
- Yuichi Tsuchiya
- Department of Biochemistry, Toho University School of Medicine, Tokyo 143-8540, Japan.
| | - Osamu Nakabayashi
- Department of Biochemistry, Toho University School of Medicine, Tokyo 143-8540, Japan.
| | - Hiroyasu Nakano
- Department of Biochemistry, Toho University School of Medicine, Tokyo 143-8540, Japan.
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22
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Molecular architecture of the DED chains at the DISC: regulation of procaspase-8 activation by short DED proteins c-FLIP and procaspase-8 prodomain. Cell Death Differ 2015; 23:681-94. [PMID: 26494467 DOI: 10.1038/cdd.2015.137] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 07/30/2015] [Accepted: 08/03/2015] [Indexed: 12/17/2022] Open
Abstract
The CD95/Fas/APO-1 death-inducing signaling complex (DISC), comprising CD95, FADD, procaspase-8, procaspase-10, and c-FLIP, has a key role in apoptosis induction. Recently, it was demonstrated that procaspase-8 activation is driven by death effector domain (DED) chains at the DISC. Here, we analyzed the molecular architecture of the chains and the role of the short DED proteins in regulating procaspase-8 activation in the chain model. We demonstrate that the DED chains are largely composed of procaspase-8 cleavage products and, in particular, of its prodomain. The DED chain also comprises c-FLIP and procaspase-10 that are present in 10 times lower amounts compared with procaspase-8. We show that short c-FLIP isoforms can inhibit CD95-induced cell death upon overexpression, likely by forming inactive heterodimers with procaspase-8. Furthermore, we have addressed mechanisms of the termination of chain elongation using experimental and mathematical modeling approaches. We show that neither c-FLIP nor procaspase-8 prodomain terminates the DED chain, but rather the dissociation/association rates of procaspase-8 define the stability of the chain and thereby its length. In addition, we provide evidence that procaspase-8 prodomain generated at the DISC constitutes a negative feedback loop in procaspase-8 activation. Overall, these findings provide new insights into caspase-8 activation in DED chains and apoptosis initiation.
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23
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DED or alive: assembly and regulation of the death effector domain complexes. Cell Death Dis 2015; 6:e1866. [PMID: 26313917 PMCID: PMC4558505 DOI: 10.1038/cddis.2015.213] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 05/29/2015] [Accepted: 06/03/2015] [Indexed: 12/21/2022]
Abstract
Death effector domains (DEDs) are protein–protein interaction domains initially identified in proteins such as FADD, FLIP and caspase-8 involved in regulating apoptosis. Subsequently, these proteins have been shown to have important roles in regulating other forms of cell death, including necroptosis, and in regulating other important cellular processes, including autophagy and inflammation. Moreover, these proteins also have prominent roles in innate and adaptive immunity and during embryonic development. In this article, we review the various roles of DED-containing proteins and discuss recent developments in our understanding of DED complex formation and regulation. We also briefly discuss opportunities to therapeutically target DED complex formation in diseases such as cancer.
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24
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Hwang EY, Jeong MS, Park SY, Jang SB. Evidence of complex formation between FADD and c-FLIP death effector domains for the death inducing signaling complex. BMB Rep 2015; 47:488-93. [PMID: 24355299 PMCID: PMC4206723 DOI: 10.5483/bmbrep.2014.47.9.239] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Indexed: 01/18/2023] Open
Abstract
Adaptor protein FADD forms the death inducing signaling complex (DISC) by recruiting the initiating caspases-8 and -10 through homotypic death effector domain (DED) interactions. Cellular FLICE-inhibitory protein (c-FLIP) is an inhibitor of death ligand-induced apoptosis downstream of death receptors, and FADD competes with procaspase-8/10 for recruitment for DISC. However, the mechanism of action of FADD and c-FLIP proteins remain poorly understood at the molecular level. In this study, we provide evidence indicating that the death effector domain (DED) of FADD interacts directly with the death effector domain of human c-FLIP. In addition, we use homology modeling to develop a molecular docking model of FADD and c-FLIP proteins. We also find that four structure-based mutants (E80A, L84A, K169A and Y171A) of c-FLIP DEDs disturb the interaction with FADD DED, and that these mutations lower the stability of the c-FLIP DED. [BMB Reports 2014; 47(9): 488-493]
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Affiliation(s)
- Eun Young Hwang
- Department of Molecular Biology, College of Natural Sciences, Pusan National University, Busan 609-735, Korea
| | - Mi Suk Jeong
- Department of Molecular Biology, College of Natural Sciences, Pusan National University, Busan 609-735, Korea
| | - So Young Park
- Department of Molecular Biology, College of Natural Sciences, Pusan National University, Busan 609-735, Korea
| | - Se Bok Jang
- Department of Molecular Biology, College of Natural Sciences, Pusan National University, Busan 609-735, Korea
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25
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Jackson TC, Du L, Janesko-Feldman K, Vagni VA, Dezfulian C, Poloyac SM, Jackson EK, Clark RSB, Kochanek PM. The nuclear splicing factor RNA binding motif 5 promotes caspase activation in human neuronal cells, and increases after traumatic brain injury in mice. J Cereb Blood Flow Metab 2015; 35:655-66. [PMID: 25586139 PMCID: PMC4420885 DOI: 10.1038/jcbfm.2014.242] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Revised: 11/06/2014] [Accepted: 12/08/2014] [Indexed: 12/31/2022]
Abstract
Splicing factors (SFs) coordinate nuclear intron/exon splicing of RNA. Splicing factor disturbances can cause cell death. RNA binding motif 5 (RBM5) and 10 (RBM10) promote apoptosis in cancer cells by activating detrimental alternative splicing of key death/survival genes. The role(s) of RBM5/10 in neurons has not been established. Here, we report that RBM5 knockdown in human neuronal cells decreases caspase activation by staurosporine. In contrast, RBM10 knockdown augments caspase activation. To determine whether brain injury alters RBM signaling, we measured RBM5/10 protein in mouse cortical/hippocampus homogenates after controlled cortical impact (CCI) traumatic brain injury (TBI) plus hemorrhagic shock (CCI+HS). The RBM5/10 staining was higher 48 to 72 hours after injury and appeared to be increased in neuronal nuclei of the hippocampus. We also measured levels of other nuclear SFs known to be essential for cellular viability and report that splicing factor 1 (SF1) but not splicing factor 3A (SF3A) decreased 4 to 72 hours after injury. Finally, we confirm that RBM5/10 regulate protein expression of several target genes including caspase-2, cellular FLICE-like inhibitory protein (c-FLIP), LETM1 Domain-Containing Protein 1 (LETMD1), and amyloid precursor-like protein 2 (APLP2) in neuronal cells. Knockdown of RBM5 appeared to increase expression of c-FLIP(s), LETMD1, and APLP2 but decrease caspase-2.
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Affiliation(s)
- Travis C Jackson
- Department of Critical Care Medicine, Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Lina Du
- Department of Critical Care Medicine, Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Keri Janesko-Feldman
- Department of Critical Care Medicine, Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Vincent A Vagni
- Department of Critical Care Medicine, Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Cameron Dezfulian
- Department of Critical Care Medicine, Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Samuel M Poloyac
- Pharmaceutical Sciences Department, University of Pittsburgh School of Pharmacy, Pittsburgh, Pennsylvania, USA
| | - Edwin K Jackson
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Robert S B Clark
- Department of Critical Care Medicine, Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Patrick M Kochanek
- Department of Critical Care Medicine, Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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He MX, He YW. c-FLIP protects T lymphocytes from apoptosis in the intrinsic pathway. THE JOURNAL OF IMMUNOLOGY 2015; 194:3444-51. [PMID: 25725104 DOI: 10.4049/jimmunol.1400469] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Apoptosis can be induced by either death receptors on the plasma membrane (extrinsic pathway) or the damage of the genome and/or cellular organelles (intrinsic pathway). Previous studies suggest that cellular caspase 8 (FLICE)-like inhibitory protein (c-FLIP) promotes cell survival in death receptor-induced apoptosis pathway in T lymphocytes. Independent of death receptor signaling, mitochondria sense apoptotic stimuli and mediate the activation of effector caspases. Whether c-FLIP regulates mitochondrion-dependent apoptotic signals remains unknown. In this study, c-FLIP gene was deleted in mature T lymphocytes in vitro, and the role of c-FLIP protein in intrinsic apoptosis pathway was studied. In resting T cells treated with the intrinsic apoptosis inducer, c-FLIP suppressed cytochrome c release from mitochondria. Bim-deletion rescued the enhanced apoptosis in c-FLIP-deficient T cells, whereas inhibition of caspase 8 did not. Different from activated T cells, there was no necroptosis or increase in reactive oxygen species in c-FLIP-deficient resting T cells. These data suggest that c-FLIP is a negative regulator of intrinsic apoptosis pathway in T lymphocytes.
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Affiliation(s)
- Ming-Xiao He
- Department of Immunology, Duke University Medical Center, Durham, NC 27710
| | - You-Wen He
- Department of Immunology, Duke University Medical Center, Durham, NC 27710
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27
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Morlé A, Garrido C, Micheau O. Hyperthermia restores apoptosis induced by death receptors through aggregation-induced c-FLIP cytosolic depletion. Cell Death Dis 2015; 6:e1633. [PMID: 25675293 PMCID: PMC4669817 DOI: 10.1038/cddis.2015.12] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 12/17/2014] [Accepted: 01/08/2015] [Indexed: 01/05/2023]
Abstract
TRAIL is involved in immune tumor surveillance and is considered a promising anti-cancer agent owing to its limited side effects on healthy cells. However, some cancer cells display resistance, or become resistant to TRAIL-induced cell death. Hyperthermia can enhance sensitivity to TRAIL-induced cell death in various resistant cancer cell lines, including lung, breast, colon or prostate carcinomas. Mild heat shock treatment has been proposed to restore Fas ligand or TRAIL-induced apoptosis through c-FLIP degradation or the mitochondrial pathway. We demonstrate here that neither the mitochondria nor c-FLIP degradation are required for TRAIL-induced cell death restoration during hyperthermia. Our data provide evidence that insolubilization of c-FLIP, alone, is sufficient to enhance apoptosis induced by death receptors. Hyperthermia induced c-FLIP depletion from the cytosolic fraction, without apparent degradation, thereby preventing c-FLIP recruitment to the TRAIL DISC and allowing efficient caspase-8 cleavage and apoptosis. Hyperthermia-induced c-FLIP depletion was independent of c-FLIP DED2 FL chain assembly motif or ubiquitination-mediated c-FLIP degradation, as assessed using c-FLIP point mutants on lysine 167 and 195 or threonine 166, a phosphorylation site known to regulate ubiquitination of c-FLIP. Rather, c-FLIP depletion was associated with aggregation, because addition of glycerol not only prevented the loss of c-FLIP from the cytosol but also enabled c-FLIP recruitment within the TRAIL DISC, thus inhibiting TRAIL-induced apoptosis during hyperthermia. Altogether our results demonstrate that c-FLIP is a thermosensitive protein whose targeting by hyperthermia allows restoration of apoptosis induced by TNF ligands, including TRAIL. Our findings suggest that combining TRAIL agonists with whole-body or localized hyperthermia may be an interesting approach in cancer therapy.
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Affiliation(s)
- A Morlé
- 1] INSERM, UMR866, Dijon, F-21079 France [2] Faculty of Medicine and Pharmacy, Univ. Bourgogne, Dijon, F-21079 France
| | - C Garrido
- 1] INSERM, UMR866, Dijon, F-21079 France [2] Faculty of Medicine and Pharmacy, Univ. Bourgogne, Dijon, F-21079 France [3] Centre Georges-François Leclerc, Dijon, F-21000 France
| | - O Micheau
- 1] INSERM, UMR866, Dijon, F-21079 France [2] Faculty of Medicine and Pharmacy, Univ. Bourgogne, Dijon, F-21079 France [3] Centre Georges-François Leclerc, Dijon, F-21000 France
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28
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Abstract
Molluscum contagiosum virus (MCV) is the causative agent of molluscum contagiosum (MC), the third most common viral skin infection in children, and one of the five most prevalent skin diseases worldwide. No FDA-approved treatments, vaccines, or commercially available rapid diagnostics for MCV are available. This review discusses several aspects of this medically important virus including: physical properties of MCV, MCV pathogenesis, MCV replication, and immune responses to MCV infection. Sequencing of the MCV genome revealed novel immune evasion molecules which are highlighted here. Special attention is given to the MCV MC159 and MC160 proteins. These proteins are FLIPs with homologs in gamma herpesviruses and in the cell. They are of great interest because each protein regulates apoptosis, NF-κB, and IRF3. However, the mechanism that each protein uses to impart its effects is different. It is important to elucidate how MCV inhibits immune responses; this knowledge contributes to our understanding of viral pathogenesis and also provides new insights into how the immune system neutralizes virus infections.
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29
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Ewald F, Annemann M, Pils MC, Plaza-Sirvent C, Neff F, Erck C, Reinhold D, Schmitz I. Constitutive expression of murine c-FLIPR causes autoimmunity in aged mice. Cell Death Dis 2014; 5:e1168. [PMID: 24722293 PMCID: PMC5424115 DOI: 10.1038/cddis.2014.138] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 02/27/2014] [Accepted: 02/28/2014] [Indexed: 02/06/2023]
Abstract
Death receptor-mediated apoptosis is a key mechanism for the control of immune responses and dysregulation of this pathway may lead to autoimmunity. Cellular FLICE-inhibitory proteins (c-FLIPs) are known as inhibitors of death receptor-mediated apoptosis. The only short murine c-FLIP splice variant is c-FLIPRaji (c-FLIPR). To investigate the functional role of c-FLIPR in the immune system, we used the vavFLIPR mouse model constitutively expressing murine c-FLIPR in all hematopoietic compartments. Lymphocytes from these mice are protected against CD95-mediated apoptosis and activation-induced cell death. Young vavFLIPR mice display normal lymphocyte compartments, but the lymphocyte populations alter with age. We identified reduced levels of T cells and slightly higher levels of B cells in 1-year-old vavFLIPR mice compared with wild-type (WT) littermates. Moreover, both B and T cells from aged vavFLIPR animals show activated phenotypes. Sera from 1-year-old WT and transgenic animals were analysed for anti-nuclear antibodies. Notably, elevated titres of these autoantibodies were detected in vavFLIPR sera. Furthermore, tissue damage in kidneys and lungs from aged vavFLIPR animals was observed, indicating that vavFLIPR mice develop a systemic lupus erythematosus-like phenotype with age. Taken together, these data suggest that c-FLIPR is an important modulator of apoptosis and enforced expression leads to autoimmunity.
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Affiliation(s)
- F Ewald
- 1] Institute of Molecular and Clinical Immunology, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, Magdeburg, Germany [2] Research Group of Systems-Oriented Immunology and Inflammation Research, Department of Immune Control, Helmholtz Centre for Infection Research, Inhoffenstr. 7, Braunschweig, Germany
| | - M Annemann
- 1] Institute of Molecular and Clinical Immunology, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, Magdeburg, Germany [2] Research Group of Systems-Oriented Immunology and Inflammation Research, Department of Immune Control, Helmholtz Centre for Infection Research, Inhoffenstr. 7, Braunschweig, Germany
| | - M C Pils
- Mouse Pathology, Animal Experimental Unit, Helmholtz Centre for Infection Research, Inhoffenstr. 7, Braunschweig, Germany
| | - C Plaza-Sirvent
- 1] Institute of Molecular and Clinical Immunology, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, Magdeburg, Germany [2] Research Group of Systems-Oriented Immunology and Inflammation Research, Department of Immune Control, Helmholtz Centre for Infection Research, Inhoffenstr. 7, Braunschweig, Germany
| | - F Neff
- Institute of Pathology, Helmholtz Centre Munich, Ingolstaedter Landstr. 1, Neuherberg, Germany
| | - C Erck
- Cellular Proteome Research, Department of Structure and Function of Proteins, Helmholtz Centre for Infection Research, Inhoffenstr. 7, Braunschweig, Germany
| | - D Reinhold
- Institute of Molecular and Clinical Immunology, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, Magdeburg, Germany
| | - I Schmitz
- 1] Institute of Molecular and Clinical Immunology, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, Magdeburg, Germany [2] Research Group of Systems-Oriented Immunology and Inflammation Research, Department of Immune Control, Helmholtz Centre for Infection Research, Inhoffenstr. 7, Braunschweig, Germany
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30
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Majkut J, Sgobba M, Holohan C, Crawford N, Logan AE, Kerr E, Higgins CA, Redmond KL, Riley JS, Stasik I, Fennell DA, Van Schaeybroeck S, Haider S, Johnston PG, Haigh D, Longley DB. Differential affinity of FLIP and procaspase 8 for FADD's DED binding surfaces regulates DISC assembly. Nat Commun 2014; 5:3350. [PMID: 24577104 PMCID: PMC3942653 DOI: 10.1038/ncomms4350] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Accepted: 01/30/2014] [Indexed: 01/05/2023] Open
Abstract
Death receptor activation triggers recruitment of FADD, which via its death effector domain (DED) engages the DEDs of procaspase 8 and its inhibitor FLIP to form death-inducing signalling complexes (DISCs). The DEDs of FADD, FLIP and procaspase 8 interact with one another using two binding surfaces defined by α1/α4 and α2/α5 helices, respectively. Here we report that FLIP has preferential affinity for the α1/α4 surface of FADD, whereas procaspase 8 has preferential affinity for FADD's α2/α5 surface. These relative affinities contribute to FLIP being recruited to the DISC at comparable levels to procaspase 8 despite lower cellular expression. Additional studies, including assessment of DISC stoichiometry and functional assays, suggest that following death receptor recruitment, the FADD DED preferentially engages FLIP using its α1/α4 surface and procaspase 8 using its α2/α5 surface; these tripartite intermediates then interact via the α1/α4 surface of FLIP DED1 and the α2/α5 surface of procaspase 8 DED2.
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Affiliation(s)
- J Majkut
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, UK
| | - M Sgobba
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, UK
- Now at Department of Bioengineering and Therapeutic Sciences, University of California
| | - C Holohan
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, UK
| | - N Crawford
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, UK
| | - A E Logan
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, UK
| | - E Kerr
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, UK
| | - C A Higgins
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, UK
| | - K L Redmond
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, UK
| | - J S Riley
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, UK
| | - I Stasik
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, UK
| | - D A Fennell
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, UK
- Now at Cancer Studies and Molecular Medicine, University of Leicester, UK
| | - S Van Schaeybroeck
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, UK
| | - S Haider
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, UK
- Now at School of Pharmacy, University College London
| | - P G Johnston
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, UK
| | - D Haigh
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, UK
| | - D B Longley
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, UK
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31
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Abstract
Cellular FLICE (FADD-like IL-1beta-converting enzyme)-inhibitory protein (c-FLIP) is a major resistance factor and critical anti-apoptotic regulator that inhibits tumor necrosis factor-alpha (TNF-alpha), Fas-L, and TNF-related apoptosis-inducing ligand (TRAIL)-induced apoptosis as well as chemotherapy-triggered apoptosis in malignant cells. c-FLIP is expressed as long (c-FLIP(L)), short (c-FLIP(S)), and c-FLIP(R) splice variants in human cells. c-FLIP binds to FADD and/or caspase-8 or -10 in a ligand-dependent and-independent fashion, which in turn prevents death-inducing signaling complex (DISC) formation and subsequent activation of the caspase cascade. Moreover, c-FLIP(L) and c-FLIP(S) are known to have multifunctional roles in various signaling pathways, as well as activating and/or upregulating several cytoprotective signaling molecules. Upregulation of c-FLIP has been found in various tumor types, and its downregulation has been shown to restore apoptosis triggered by cytokines and various chemotherapeutic agents. Hence, c-FLIP is an important target for cancer therapy. For example, small interfering RNAs (siRNAs) that specifically knockdown the expression of c-FLIP(L) in diverse human cancer cell lines augmented TRAIL-induced DISC recruitment and increased the efficacy of chemotherapeutic agents, thereby enhancing effector caspase stimulation and apoptosis. Moreover, small molecules causing degradation of c-FLIP as well as decreasing mRNA and protein levels of c-FLIP(L) and c-FLIP(S) splice variants have been found, and efforts are underway to develop other c-FLIP-targeted cancer therapies. This review focuses on (1) the functional role of c-FLIP splice variants in preventing apoptosis and inducing cytokine and drug resistance; (2) the molecular mechanisms that regulate c-FLIP expression; and (3) strategies to inhibit c-FLIP expression and function.
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32
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SAHA overcomes FLIP-mediated inhibition of SMAC mimetic-induced apoptosis in mesothelioma. Cell Death Dis 2013; 4:e733. [PMID: 23868066 PMCID: PMC3730428 DOI: 10.1038/cddis.2013.258] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 06/06/2013] [Accepted: 06/07/2013] [Indexed: 11/08/2022]
Abstract
Malignant pleural mesothelioma (MPM) is a highly pro-inflammatory malignancy that is rapidly fatal and increasing in incidence. Cytokine signaling within the pro-inflammatory tumor microenvironment makes a critical contribution to the development of MPM and its resistance to conventional chemotherapy approaches. SMAC mimetic compounds (SMCs) are a promising class of anticancer drug that are dependent on tumor necrosis factor alpha (TNFα) signaling for their activity. As circulating TNFα expression is significantly elevated in MPM patients, we examined the sensitivity of MPM cell line models to SMCs. Surprisingly, all MPM cell lines assessed were highly resistant to SMCs either alone or when incubated in the presence of clinically relevant levels of TNFα. Further analyses revealed that MPM cells were sensitized to SMC-induced apoptosis by siRNA-mediated downregulation of the caspase 8 inhibitor FLIP, an antiapoptotic protein overexpressed in several cancer types including MPM. We have previously reported that FLIP expression is potently downregulated in MPM cells in response to the histone deacetylase inhibitor (HDACi) Vorinostat (SAHA). In this study, we demonstrate that SAHA sensitizes MPM cells to SMCs in a manner dependent on its ability to downregulate FLIP. Although treatment with SMC in the presence of TNFα promoted interaction between caspase 8 and the necrosis-promoting RIPK1, the cell death induced by combined treatment with SAHA and SMC was apoptotic and mediated by caspase 8. These results indicate that FLIP is a major inhibitor of SMC-mediated apoptosis in MPM, but that this inhibition can be overcome by the HDACi SAHA.
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33
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Telieps T, Ewald F, Gereke M, Annemann M, Rauter Y, Schuster M, Ueffing N, von Smolinski D, Gruber AD, Bruder D, Schmitz I. Cellular-FLIP, Raji isoform (c-FLIP R) modulates cell death induction upon T-cell activation and infection. Eur J Immunol 2013; 43:1499-510. [PMID: 23505065 DOI: 10.1002/eji.201242819] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 01/25/2013] [Accepted: 03/07/2013] [Indexed: 12/25/2022]
Abstract
Dysregulation of apoptosis caused by an imbalance of pro- and anti-apoptotic protein expression can lead to cancer, neurodegenerative, and autoimmune diseases. Cellular-FLIP (c-FLIP) proteins inhibit apoptosis directly at the death-inducing signaling complex of death receptors, such as CD95, and have been linked to apoptosis regulation during immune responses. While the isoforms c-FLIPL and c-FLIPS are well characterized, the function of c-FLIPR remains poorly understood. Here, we demonstrate the induction of endogenous murine c-FLIPR in activated lymphocytes for the first time. To analyze c-FLIPR function in vivo, we generated transgenic mice expressing murine c-FLIPR specifically in hematopoietic cells. As expected, lymphocytes from c-FLIPR transgenic mice were protected against CD95-induced apoptosis in vitro. In the steady state, transgenic mice had normal cell numbers and unaltered frequencies of B cells and T-cell subsets in lymphoid organs. However, when challenged with Listeria monocytogenes, c-FLIPR transgenic mice showed less liver necrosis and better bacterial clearance compared with infected wild-type mice. We conclude that c-FLIPR expression in hematopoietic cells supports an efficient immune response against bacterial infections.
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Affiliation(s)
- Tanja Telieps
- Laboratory of Systems-Oriented Immunology and Inflammation Research, Institute of Molecular and Clinical Immunology, Otto-von-Guericke-University, Magdeburg, Germany
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34
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Phosphorylation of Atg5 by the Gadd45β-MEKK4-p38 pathway inhibits autophagy. Cell Death Differ 2012; 20:321-32. [PMID: 23059785 DOI: 10.1038/cdd.2012.129] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Autophagy is a lysosomal degradation pathway important for cellular homeostasis, mammalian development, cancer and immunity. Many molecular components of autophagy have been identified, but little is known about regulatory mechanisms controlling their effector functions. Here, we show that, in contrast to other p38 MAP kinase activators, the growth arrest and DNA damage 45 beta (Gadd45β)-MAPK/ERK kinase kinase 4 (MEKK4) pathway specifically directs p38 to autophagosomes. This process results in an accumulation of autophagosomes through p38-mediated inhibition of lysosome fusion. Conversely, autophagic flux is increased in p38-deficient fibroblasts and Gadd45β-deficient cells. We further identified the underlying mechanism and demonstrate that phosphorylation of the autophagy regulator autophagy-related (Atg)5 at threonine 75 through p38 is responsible for inhibition of starvation-induced autophagy. Thus, we show for the first time that Atg5 activity is controlled by phosphorylation and, moreover, that the spatial regulation of p38 by Gadd45β/MEKK4 negatively regulates the autophagic process.
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35
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Kerr E, Holohan C, McLaughlin KM, Majkut J, Dolan S, Redmond K, Riley J, McLaughlin K, Stasik I, Crudden M, Van Schaeybroeck S, Fenning C, O'Connor R, Kiely P, Sgobba M, Haigh D, Johnston PG, Longley DB. Identification of an acetylation-dependant Ku70/FLIP complex that regulates FLIP expression and HDAC inhibitor-induced apoptosis. Cell Death Differ 2012; 19:1317-27. [PMID: 22322857 PMCID: PMC3392639 DOI: 10.1038/cdd.2012.8] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Revised: 12/21/2011] [Accepted: 12/21/2011] [Indexed: 12/31/2022] Open
Abstract
FLIP is a potential anti-cancer therapeutic target that inhibits apoptosis by blocking caspase 8 activation by death receptors. We report a novel interaction between FLIP and the DNA repair protein Ku70 that regulates FLIP protein stability by inhibiting its polyubiquitination. Furthermore, we found that the histone deacetylase (HDAC) inhibitor Vorinostat (SAHA) enhances the acetylation of Ku70, thereby disrupting the FLIP/Ku70 complex and triggering FLIP polyubiquitination and degradation by the proteasome. Using in vitro and in vivo colorectal cancer models, we further demonstrated that SAHA-induced apoptosis is dependant on FLIP downregulation and caspase 8 activation. In addition, an HDAC6-specific inhibitor Tubacin recapitulated the effects of SAHA, suggesting that HDAC6 is a key regulator of Ku70 acetylation and FLIP protein stability. Thus, HDAC inhibitors with anti-HDAC6 activity act as efficient post-transcriptional suppressors of FLIP expression and may, therefore, effectively act as 'FLIP inhibitors'.
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Affiliation(s)
- E Kerr
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, UK
| | - C Holohan
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, UK
| | - K M McLaughlin
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, UK
| | - J Majkut
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, UK
| | - S Dolan
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, UK
| | - K Redmond
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, UK
| | - J Riley
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, UK
| | - K McLaughlin
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, UK
| | - I Stasik
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, UK
| | - M Crudden
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, UK
| | - S Van Schaeybroeck
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, UK
| | - C Fenning
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, UK
| | - R O'Connor
- Cell Biology Laboratory, Department of Biochemistry, University College Cork, Cork, Republic of Ireland
| | - P Kiely
- Cell Biology Laboratory, Department of Biochemistry, University College Cork, Cork, Republic of Ireland
| | - M Sgobba
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, UK
| | - D Haigh
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, UK
| | - P G Johnston
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, UK
| | - D B Longley
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, UK
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36
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Baldwin AS. Regulation of cell death and autophagy by IKK and NF-κB: critical mechanisms in immune function and cancer. Immunol Rev 2012; 246:327-45. [PMID: 22435564 DOI: 10.1111/j.1600-065x.2012.01095.x] [Citation(s) in RCA: 216] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The cellular response to survive or to undergo death is fundamental to the benefit of the organism, and errors in this process can lead to autoimmunity and cancer. The transcription factor nuclear factor κB (NF-κB) functions to block cell death through transcriptional induction of genes encoding anti-apoptotic and antioxidant proteins. This is essential for survival of activated cells of the immune system and for cells undergoing a DNA damage response. In Ras-transformed cells and tumors as well as other cancers, NF-κB functions to suppress apoptosis--a hallmark of cancer. Critical prosurvival roles for inhibitor of NF-κB kinase (IKK) family members, including IKKε and TBK1, have been reported, which are both NF-κB-dependent and -independent. While the roles of NF-κB in promoting cell survival in lymphocytes and in cancers is relatively clear, evidence has been presented that NF-κB can promote cell death in particular contexts. Recently, IKK was shown to play a critical role in the induction of autophagy, a metabolic response typically associated with cell survival but which can lead to cell death. This review provides an historical perspective, along with new findings, regarding the roles of the IKK and NF-κB pathways in regulating cell survival.
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Affiliation(s)
- Albert S Baldwin
- Lineberger Comprehensive Cancer Center, The University of North Carolina, Chapel Hill, NC 27599, USA.
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37
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Cellular FLICE-like inhibitory proteins (c-FLIPs): fine-tuners of life and death decisions. Exp Cell Res 2012; 318:1324-31. [PMID: 22309778 DOI: 10.1016/j.yexcr.2012.01.019] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 01/20/2012] [Accepted: 01/21/2012] [Indexed: 11/21/2022]
Abstract
c-FLIP proteins (isoforms: c-FLIP(L), c-FLIP(S), and c-FLIP(R)) play an essential role in the regulation of death receptor (DR)-induced apoptosis and NF-κB activation. Here, we discuss multiple mechanisms by which c-FLIPs control NF-κB activation and the life/death decision made in cancer and immune cells. We focus on the role of c-FLIP in cellular signaling. We concentrate on c-FLIP protein modifications as well as on the regulation of c-FLIP expression levels. Furthermore, we discuss in detail how the exact quantity and dynamics of different c-FLIP isoforms in the cell influence the induction of pro- versus anti-apoptotic pathways.
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38
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Eblen ST. Regulation of chemoresistance via alternative messenger RNA splicing. Biochem Pharmacol 2012; 83:1063-72. [PMID: 22248731 DOI: 10.1016/j.bcp.2011.12.041] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Revised: 12/29/2011] [Accepted: 12/29/2011] [Indexed: 12/17/2022]
Abstract
The acquisition of resistance to chemotherapy is a significant problem in the treatment of cancer, greatly increasing patient morbidity and mortality. Tumors are often sensitive to chemotherapy upon initial treatment, but repeated treatments can select for those cells that were able to survive initial therapy and have acquired cellular mechanisms to enhance their resistance to subsequent chemotherapy treatment. Many cellular mechanisms of drug resistance have been identified, most of which result from changes in gene and protein expression. While changes at the transcriptional level have been duly noted, it is primarily the post-transcriptional processing of pre-mRNA into mature mRNA that regulates the composition of the proteome and it is the proteome that actually regulates the cell's response to chemotherapeutic insult, inducing cell survival or death. During pre-mRNA processing, intronic non-protein-coding sequences are removed and protein-coding exons are spliced to form a continuous template for protein translation. Alternative splicing involves the differential inclusion or exclusion of exonic sequences into the mature transcript, generating different mRNA templates for protein production. This regulatory mechanism enables the potential to produce many different protein isoforms from the same gene. In this review I will explain the mechanism of alternative pre-mRNA splicing and look at some specific examples of how splicing factors, splicing factor kinases and alternative splicing of specific pre-mRNAs from genes have been shown to contribute to acquisition of the drug resistant phenotype.
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Affiliation(s)
- Scott T Eblen
- Department of Cell and Molecular Pharmacology, Medical University of South Carolina, Charleston, 29425, USA.
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Ewald F, Ueffing N, Brockmann L, Hader C, Telieps T, Schuster M, Schulz WA, Schmitz I. The role of c-FLIP splice variants in urothelial tumours. Cell Death Dis 2011; 2:e245. [PMID: 22190004 PMCID: PMC3252741 DOI: 10.1038/cddis.2011.131] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Accepted: 11/16/2011] [Indexed: 01/01/2023]
Abstract
Deregulation of apoptosis is common in cancer and is often caused by overexpression of anti-apoptotic proteins in tumour cells. One important regulator of apoptosis is the cellular FLICE-inhibitory protein (c-FLIP), which is overexpressed, for example, in melanoma and Hodgkin's lymphoma cells. Here, we addressed the question whether deregulated c-FLIP expression in urothelial carcinoma impinges on the ability of death ligands to induce apoptosis. In particular, we investigated the role of the c-FLIP splice variants c-FLIP(long) (c-FLIP(L)) and c-FLIP(short) (c-FLIP(S)), which can have opposing functions. We observed diminished expression of the c-FLIP(L) isoform in urothelial carcinoma tissues as well as in established carcinoma cell lines compared with normal urothelial tissues and cells, whereas c-FLIP(S) was unchanged. Overexpression and RNA interference studies in urothelial cell lines nevertheless demonstrated that c-FLIP remained a crucial factor conferring resistance towards induction of apoptosis by death ligands CD95L and TRAIL. Isoform-specific RNA interference showed c-FLIP(L) to be of particular importance. Thus, urothelial carcinoma cells appear to fine-tune c-FLIP expression to a level sufficient for protection against activation of apoptosis by the extrinsic pathway. Therefore, targeting c-FLIP, and especially the c-FLIP(L) isoform, may facilitate apoptosis-based therapies of bladder cancer in otherwise resistant tumours.
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Affiliation(s)
- F Ewald
- Laboratory of Systems-oriented Immunology and Inflammation Research, Institute of Molecular and Clinical Immunology, Otto-von-Guericke-University Magdeburg and Department of Immune Control, Helmholtz Centre for Infection Research, Inhoffenstr 7, D-38124 Braunschweig, Germany
| | - N Ueffing
- Institute of Medical Microbiology and Hospital Hygiene, Heinrich-Heine-University, Universitaetsstr 1, D-40225 Duesseldorf, Germany
| | - L Brockmann
- Institute of Medical Microbiology and Hospital Hygiene, Heinrich-Heine-University, Universitaetsstr 1, D-40225 Duesseldorf, Germany
| | - C Hader
- Department of Urology, Heinrich Heine University, D-40225 Duesseldorf, Germany
| | - T Telieps
- Laboratory of Systems-oriented Immunology and Inflammation Research, Institute of Molecular and Clinical Immunology, Otto-von-Guericke-University Magdeburg and Department of Immune Control, Helmholtz Centre for Infection Research, Inhoffenstr 7, D-38124 Braunschweig, Germany
| | - M Schuster
- Laboratory of Systems-oriented Immunology and Inflammation Research, Institute of Molecular and Clinical Immunology, Otto-von-Guericke-University Magdeburg and Department of Immune Control, Helmholtz Centre for Infection Research, Inhoffenstr 7, D-38124 Braunschweig, Germany
| | - W A Schulz
- Department of Urology, Heinrich Heine University, D-40225 Duesseldorf, Germany
| | - I Schmitz
- Laboratory of Systems-oriented Immunology and Inflammation Research, Institute of Molecular and Clinical Immunology, Otto-von-Guericke-University Magdeburg and Department of Immune Control, Helmholtz Centre for Infection Research, Inhoffenstr 7, D-38124 Braunschweig, Germany
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Kober AMM, Legewie S, Pforr C, Fricker N, Eils R, Krammer PH, Lavrik IN. Caspase-8 activity has an essential role in CD95/Fas-mediated MAPK activation. Cell Death Dis 2011; 2:e212. [PMID: 21975294 PMCID: PMC3219090 DOI: 10.1038/cddis.2011.93] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Stimulation of CD95/Fas/APO-1 results in the induction of both apoptotic and non-apoptotic signaling pathways. The processes regulating these two opposing pathways have not been thoroughly elucidated to date. In this study, using quantitative immunoblots, imaging, and mathematical modeling, we addressed the dynamics of the DED proteins of the death-inducing signaling complex (DISC), procaspase-8, and cellular FLICE inhibitory proteins (c-FLIPs) to the onset of CD95-mediated ERK1/2 and p38 mitogen-activated protein kinase (MAPK) activation. We found that CD95 DISC-induced caspase-8 activity is important for the initiation of ERK1/2 and p38 MAPK activation. The long c-FLIP isoform, c-FLIP(L), and the short c-FLIP isoform, c-FLIP(R), inhibited MAPK induction by blocking caspase-8 processing at the DISC. Furthermore, we built a mathematical model describing CD95 DISC-mediated MAPK activation and apoptosis. The model quantitatively defined the dynamics of DED proteins, procaspase-8, and c-FLIP, which lead to caspase-8 activation and induction of apoptotic and non-apoptotic signaling pathways. In conclusion, the combination of biochemical analysis with mathematical modeling provides evidence for an important role of caspase-8 in CD95-mediated activation of MAPKs, while c-FLIP exerts a regulatory function in this process.
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Affiliation(s)
- A M M Kober
- Division of Immunogenetics, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
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Abstract
Fas (also called CD95 or APO-1), a member of a subgroup of the tumour necrosis factor receptor superfamily that contain an intracellular death domain, can initiate apoptosis signalling and has a critical role in the regulation of the immune system. Fas-induced apoptosis requires recruitment and activation of the initiator caspase, caspase-8 (in humans also caspase-10), within the death-inducing signalling complex. In so-called type 1 cells, proteolytic activation of effector caspases (-3 and -7) by caspase-8 suffices for efficient apoptosis induction. In so-called type 2 cells, however, killing requires amplification of the caspase cascade. This can be achieved through caspase-8-mediated proteolytic activation of the pro-apoptotic Bcl-2 homology domain (BH)3-only protein BH3-interacting domain death agonist (Bid), which then causes mitochondrial outer membrane permeabilisation. This in turn leads to mitochondrial release of apoptogenic proteins, such as cytochrome c and, pertinent for Fas death receptor (DR)-induced apoptosis, Smac/DIABLO (second mitochondria-derived activator of caspase/direct IAP binding protein with low Pi), an antagonist of X-linked inhibitor of apoptosis (XIAP), which imposes a brake on effector caspases. In this review, written in honour of Juerg Tschopp who contributed so much to research on cell death and immunology, we discuss the functions of Bid and XIAP in the control of Fas DR-induced apoptosis signalling, and we speculate on how this knowledge could be exploited to develop novel regimes for treatment of cancer.
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Abstract
During the development and normal function of T lymphocytes, the cells are subject to several checkpoints at which they must "decide" to live or die. At these critical times and during homeostasis, the molecules that regulate the classical apoptotic pathways and survival pathways such as autophagy have critical roles in controlling this decision. Our laboratory has focused on the roles of apoptotic and autophagic proteins in T lymphocyte development and function. Using genetic models in mice and in vitro analyses of T cell functions, we have outlined critical roles for the Bcl-2 family (regulators of the intrinsic pathway of apoptosis), c-FLIP (an anti-apoptotic protein in the extrinsic pathway of apoptosis), and autophagy in T lymphocytes.
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Toivonen HT, Meinander A, Asaoka T, Westerlund M, Pettersson F, Mikhailov A, Eriksson JE, Saxén H. Modeling reveals that dynamic regulation of c-FLIP levels determines cell-to-cell distribution of CD95-mediated apoptosis. J Biol Chem 2011; 286:18375-82. [PMID: 21324892 PMCID: PMC3099654 DOI: 10.1074/jbc.m110.177097] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Revised: 02/11/2011] [Indexed: 12/22/2022] Open
Abstract
The expression levels of caspase-8 inhibitory c-FLIP proteins play an important role in regulating death receptor-mediated apoptosis, as their concentration at the moment when the death-inducing signaling complex (DISC) is formed determines the outcome of the DISC signal. Experimental studies have shown that c-FLIP proteins are subject to dynamic turnover and that their stability and expression levels can be rapidly altered. Even though the influence of c-FLIP on the apoptotic behavior of a single cell has been captured in mathematical simulation studies, the effect of c-FLIP turnover and stability has not been investigated. In this study, a mathematical model of apoptosis was developed to analyze how the dynamic turnover and stability of the c-FLIP isoforms regulate apoptotic signaling for both individual cells and cell populations. Intercellular parameter and concentration distributions were used to describe the behavior of cell populations. Monte-Carlo simulations of cell populations showed that c-FLIP turnover is a key determinant of death receptor responses. The fact that the developed model simulates the state of whole cell populations makes it possible to validate it by comparison with empirical data. The proposed modeling approach can be used to further determine limiting factors in the DISC signaling process.
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Affiliation(s)
| | | | - Tomoko Asaoka
- Biosciences and
- Turku Centre for Biotechnology, Åbo Akademi University and University of Turku, FI-20520 Turku, Finland
| | | | - Frank Pettersson
- Chemical Engineering, Åbo Akademi University, FI-20500 Turku, Finland and
| | | | - John E. Eriksson
- Biosciences and
- Turku Centre for Biotechnology, Åbo Akademi University and University of Turku, FI-20520 Turku, Finland
| | - Henrik Saxén
- Chemical Engineering, Åbo Akademi University, FI-20500 Turku, Finland and
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Regulation of cell death by c-FLIP phosphorylation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 691:625-30. [PMID: 21153369 DOI: 10.1007/978-1-4419-6612-4_66] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
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Fricker N, Beaudouin J, Richter P, Eils R, Krammer PH, Lavrik IN. Model-based dissection of CD95 signaling dynamics reveals both a pro- and antiapoptotic role of c-FLIPL. ACTA ACUST UNITED AC 2010; 190:377-89. [PMID: 20696707 PMCID: PMC2922645 DOI: 10.1083/jcb.201002060] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
A systems biology–based approach shows that life and death decisions for cells depend on the stoichiometry of c-FLIP isoforms. Cellular FADD-like interleukin-1β–converting enzyme inhibitory proteins (c-FLIPs; isoforms c-FLIP long [c-FLIPL], c-FLIP short [c-FLIPS], and c-FLIP Raji [c-FLIPR]) regulate caspase-8 activation and death receptor (DR)–induced apoptosis. In this study, using a combination of mathematical modeling, imaging, and quantitative Western blots, we present a new mathematical model describing caspase-8 activation in quantitative terms, which highlights the influence of c-FLIP proteins on this process directly at the CD95 death-inducing signaling complex. We quantitatively define how the stoichiometry of c-FLIP proteins determines sensitivity toward CD95-induced apoptosis. We show that c-FLIPL has a proapoptotic role only upon moderate expression in combination with strong receptor stimulation or in the presence of high amounts of one of the short c-FLIP isoforms, c-FLIPS or c-FLIPR. Our findings resolve the present controversial discussion on the function of c-FLIPL as a pro- or antiapoptotic protein in DR-mediated apoptosis and are important for understanding the regulation of CD95-induced apoptosis, where subtle differences in c-FLIP concentrations determine life or death of the cells.
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Affiliation(s)
- Nicolai Fricker
- Division of Immunogenetics, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
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Lluis JM, Nachbur U, Cook WD, Gentle IE, Moujalled D, Moulin M, Wong WWL, Khan N, Chau D, Callus BA, Vince JE, Silke J, Vaux DL. TAK1 is required for survival of mouse fibroblasts treated with TRAIL, and does so by NF-kappaB dependent induction of cFLIPL. PLoS One 2010; 5:e8620. [PMID: 20062539 PMCID: PMC2797639 DOI: 10.1371/journal.pone.0008620] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Accepted: 12/06/2009] [Indexed: 12/21/2022] Open
Abstract
Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is known as a “death ligand”—a member of the TNF superfamily that binds to receptors bearing death domains. As well as causing apoptosis of certain types of tumor cells, TRAIL can activate both NF-κB and JNK signalling pathways. To determine the role of TGF-β-Activated Kinase-1 (TAK1) in TRAIL signalling, we analyzed the effects of adding TRAIL to mouse embryonic fibroblasts (MEFs) derived from TAK1 conditional knockout mice. TAK1−/− MEFs were significantly more sensitive to killing by TRAIL than wild-type MEFs, and failed to activate NF-κB or JNK. Overexpression of IKK2-EE, a constitutive activator of NF-κB, protected TAK1−/− MEFs against TRAIL killing, suggesting that TAK1 activation of NF-κB is critical for the viability of cells treated with TRAIL. Consistent with this model, TRAIL failed to induce the survival genes cIAP2 and cFlipL in the absence of TAK1, whereas activation of NF-κB by IKK2-EE restored the levels of both proteins. Moreover, ectopic expression of cFlipL, but not cIAP2, in TAK1−/− MEFs strongly inhibited TRAIL-induced cell death. These results indicate that cells that survive TRAIL treatment may do so by activation of a TAK1–NF-κB pathway that drives expression of cFlipL, and suggest that TAK1 may be a good target for overcoming TRAIL resistance.
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Affiliation(s)
| | - Ulrich Nachbur
- Deparment of Biochemistry, La Trobe University, Bundoora, Australia
| | - Wendy Diane Cook
- Deparment of Biochemistry, La Trobe University, Bundoora, Australia
| | | | - Donia Moujalled
- Deparment of Biochemistry, La Trobe University, Bundoora, Australia
| | - Maryline Moulin
- Deparment of Biochemistry, La Trobe University, Bundoora, Australia
| | | | - Nufail Khan
- Deparment of Biochemistry, La Trobe University, Bundoora, Australia
| | - Diep Chau
- Deparment of Biochemistry, La Trobe University, Bundoora, Australia
| | - Bernard Andrew Callus
- School of Biomedical, Biomolecular and Chemical Sciences, University of Western Australia, Crawley, Australia
| | - James Edward Vince
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
| | - John Silke
- Deparment of Biochemistry, La Trobe University, Bundoora, Australia
| | - David Lawrence Vaux
- Deparment of Biochemistry, La Trobe University, Bundoora, Australia
- * E-mail:
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A single nucleotide polymorphism determines protein isoform production of the human c-FLIP protein. Blood 2009; 114:572-9. [PMID: 19439735 DOI: 10.1182/blood-2009-02-204230] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The cellular FLICE-inhibitory protein (c-FLIP) is a modulator of death receptor-mediated apoptosis and plays a major role in T- and B-cell homeostasis. Three different isoforms have been described on the protein level, including the long form c-FLIP(L) as well as 2 short forms, c-FLIP(S) and the recently identified c-FLIP(R). The mechanisms controlling c-FLIP isoform production are largely unknown. Here, we identified by sequence comparison in several mammals that c-FLIP(R) and not the widely studied c-FLIP(S) is the evolutionary ancestral short c-FLIP protein. Unexpectedly, the decision for production of either c-FLIP(S) or c-FLIP(R) in humans is defined by a single nucleotide polymorphism in a 3' splice site of the c-FLIP gene (rs10190751A/G). Whereas an intact splice site directs production of c-FLIP(S), the splice-dead variant causes production of c-FLIP(R). Interestingly, due to differences in protein translation rates, higher amounts of c-FLIP(S) protein compared with c-FLIP(R) are produced. Investigation of diverse human cell lines points to an increased frequency of c-FLIP(R) in transformed B-cell lines. A comparison of 183 patients with follicular lymphoma and 233 population controls revealed an increased lymphoma risk associated with the rs10190751 A genotype causing c-FLIP(R) expression.
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Huo J, Xu S, Guo K, Zeng Q, Lam KP. Genetic deletion of faim reveals its role in modulating c-FLIP expression during CD95-mediated apoptosis of lymphocytes and hepatocytes. Cell Death Differ 2009; 16:1062-70. [PMID: 19300454 DOI: 10.1038/cdd.2009.26] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Fas-apoptosis inhibitory molecule (FAIM) is inducibly expressed in B lymphocytes and had been shown to antagonize Fas-mediated killing of B-cell lines in vitro. However, its mechanism and role in vivo are unknown. We have generated faim(-/-) mice and found these mutants to be viable. In contrast to fas(-/-) mice, faim(-/-) mice have normal B- and T-cell populations. However, faim(-/-) B cells and thymocytes show increased sensitivity to Fas-triggered apoptosis in vitro, and faim(-/-) mice suffer greater mortality and exhibit exacerbated liver damage in response to Fas (CD95) engagement in vivo. The lack of FAIM results in greater activation of caspase-8 and -3 in Fas-stimulated thymocytes. Detailed biochemical analyses further reveal the decreased expression of c-FLIP(L) and c-FLIP(R) in faim(-/-) thymocytes and increased association of caspase-8 with Fas in Fas-activated mutant cells. Decreased levels of c-FLIP(L) and c-FLIP(R) are also evident in faim(-/-) liver. Thus, FAIM plays a novel role in modulating Fas-mediated apoptosis and acts through influencing the expression of c-FLIP and regulating the physical binding of caspase-8 to Fas.
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Affiliation(s)
- J Huo
- Laboratory of Immunology, Bioprocessing Technology Institute, Agency for Science, Technology and Research (A*STAR), Singapore
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Wilson NS, Dixit V, Ashkenazi A. Death receptor signal transducers: nodes of coordination in immune signaling networks. Nat Immunol 2009; 10:348-55. [DOI: 10.1038/ni.1714] [Citation(s) in RCA: 506] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Zhang N, Hopkins K, He YW. c-FLIP protects mature T lymphocytes from TCR-mediated killing. THE JOURNAL OF IMMUNOLOGY 2008; 181:5368-73. [PMID: 18832693 DOI: 10.4049/jimmunol.181.8.5368] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Although c-FLIP has been identified as an important player in the extrinsic (death receptor-induced) apoptosis pathway, its endogenous function in mature T lymphocytes remains undefined. c-FLIP may inhibit or promote T cell death as previous data demonstrate that the c-FLIP(L) isoform can promote or inhibit caspase 8 activation while the c-FLIP(S) isoform promotes or inhibits T cell death when overexpressed. Although the c-FLIP(R) isoform inhibits cell death in cell lines, its function in T cells remains unknown. To investigate the function of c-FLIP in mature T cells, we have generated several genetic mouse models with c-FLIP or its individual isoforms deleted in mature T cells. Surprisingly, we found that c-FLIP protects mature T cells not only from apoptosis induced by the death receptors Fas and TNFR but also from TCR-mediated and spontaneous apoptosis. Thus, c-FLIP plays an essential role in protecting mature T cells from a death signal induced through the TCR itself and is required for naive T cell survival. Our results demonstrate that c-FLIP functions beyond the extrinsic death pathway.
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Affiliation(s)
- Nu Zhang
- Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA
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