1
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Davies KA, Czabotar PE, Murphy JM. Death at a funeral: Activation of the dead enzyme, MLKL, to kill cells by necroptosis. Curr Opin Struct Biol 2024; 88:102891. [PMID: 39059047 DOI: 10.1016/j.sbi.2024.102891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 06/25/2024] [Accepted: 07/05/2024] [Indexed: 07/28/2024]
Abstract
Necroptosis is a lytic form of programmed cell death implicated in inflammatory pathologies, leading to intense interest in the underlying mechanisms and therapeutic prospects. Here, we review our current structural understanding of how the terminal executioner of the pathway, the dead kinase, mixed lineage kinase domain-like (MLKL), is converted from a dormant to killer form by the upstream regulatory kinase, RIPK3. RIPK3-mediated phosphorylation of MLKL's pseudokinase domain toggles a molecular switch that induces dissociation from a cytoplasmic platform, assembly of MLKL oligomers, and trafficking to the plasma membrane, where activated MLKL accumulates and permeabilises the lipid bilayer to induce cell death. We highlight gaps in mechanistic knowledge of MLKL's activation, how mechanisms diverge between species, and the power of modelling in advancing structural insights.
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Affiliation(s)
- Katherine A Davies
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia.
| | - Peter E Czabotar
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia.
| | - James M Murphy
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia; Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia.
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2
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Garnish SE, Horne CR, Meng Y, Young SN, Jacobsen AV, Hildebrand JM, Murphy JM. Inhibitors identify an auxiliary role for mTOR signalling in necroptosis execution downstream of MLKL activation. Biochem J 2024; 481:1125-1142. [PMID: 39136677 DOI: 10.1042/bcj20240255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2024] [Revised: 08/11/2024] [Accepted: 08/13/2024] [Indexed: 08/28/2024]
Abstract
Necroptosis is a lytic and pro-inflammatory form of programmed cell death executed by the terminal effector, the MLKL (mixed lineage kinase domain-like) pseudokinase. Downstream of death and Toll-like receptor stimulation, MLKL is trafficked to the plasma membrane via the Golgi-, actin- and microtubule-machinery, where activated MLKL accumulates until a critical lytic threshold is exceeded and cell death ensues. Mechanistically, MLKL's lytic function relies on disengagement of the N-terminal membrane-permeabilising four-helix bundle domain from the central autoinhibitory brace helix: a process that can be experimentally mimicked by introducing the R30E MLKL mutation to induce stimulus-independent cell death. Here, we screened a library of 429 kinase inhibitors for their capacity to block R30E MLKL-mediated cell death, to identify co-effectors in the terminal steps of necroptotic signalling. We identified 13 compounds - ABT-578, AR-A014418, AZD1480, AZD5363, Idelalisib, Ipatasertib, LJI308, PHA-793887, Rapamycin, Ridaforolimus, SMI-4a, Temsirolimus and Tideglusib - each of which inhibits mammalian target of rapamycin (mTOR) signalling or regulators thereof, and blocked constitutive cell death executed by R30E MLKL. Our study implicates mTOR signalling as an auxiliary factor in promoting the transport of activated MLKL oligomers to the plasma membrane, where they accumulate into hotspots that permeabilise the lipid bilayer to cause cell death.
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Affiliation(s)
- Sarah E Garnish
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria 3052, Australia
| | - Christopher R Horne
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria 3052, Australia
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Yanxiang Meng
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria 3052, Australia
| | - Samuel N Young
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3052, Australia
| | - Annette V Jacobsen
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria 3052, Australia
| | - Joanne M Hildebrand
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria 3052, Australia
| | - James M Murphy
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria 3052, Australia
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
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3
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Deng Y, Águeda-Pinto A, Brune W. No Time to Die: How Cytomegaloviruses Suppress Apoptosis, Necroptosis, and Pyroptosis. Viruses 2024; 16:1272. [PMID: 39205246 PMCID: PMC11359067 DOI: 10.3390/v16081272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2024] [Revised: 07/31/2024] [Accepted: 08/07/2024] [Indexed: 09/04/2024] Open
Abstract
Viruses are obligate intracellular pathogens as their replication depends on the metabolism of the host cell. The induction of cellular suicide, known as programmed cell death (PCD), has the potential to hinder viral replication and act as a first line of defense against viral pathogens. Apoptosis, necroptosis, and pyroptosis are three important PCD modalities. Different signaling pathways are involved in their execution, and they also differ in their ability to cause inflammation. Cytomegaloviruses (CMV), beta-herpesviruses with large double-stranded DNA genomes, encode a great variety of immune evasion genes, including several cell death suppressors. While CMV inhibitors of apoptosis and necroptosis have been known and studied for years, the first pyroptosis inhibitor has been identified and characterized only recently. Here, we describe how human and murine CMV interfere with apoptosis, necroptosis, and pyroptosis signaling pathways. We also discuss the importance of the different PCD forms and their viral inhibitors for the containment of viral replication and spread in vivo.
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Affiliation(s)
| | | | - Wolfram Brune
- Leibniz Institute of Virology (LIV), 20251 Hamburg, Germany; (Y.D.); (A.Á.-P.)
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4
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Li S, Xie Y, Yu C, Zheng C, Xu Z. The battle between host antiviral innate immunity and immune evasion by cytomegalovirus. Cell Mol Life Sci 2024; 81:341. [PMID: 39120730 PMCID: PMC11335264 DOI: 10.1007/s00018-024-05369-y] [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: 05/23/2024] [Revised: 07/10/2024] [Accepted: 07/17/2024] [Indexed: 08/10/2024]
Abstract
Cytomegalovirus (CMV) has successfully established a long-lasting latent infection in humans due to its ability to counteract the host antiviral innate immune response. During coevolution with the host, the virus has evolved various evasion techniques to evade the host's innate immune surveillance. At present, there is still no vaccine available for the prevention and treatment of CMV infection, and the interaction between CMV infection and host antiviral innate immunity is still not well understood. However, ongoing studies will offer new insights into how to treat and prevent CMV infection and its related diseases. Here, we update recent studies on how CMV evades antiviral innate immunity, with a focus on how CMV proteins target and disrupt critical adaptors of antiviral innate immune signaling pathways. This review also discusses some classic intrinsic cellular defences that are crucial to the fight against viral invasion. A comprehensive review of the evasion mechanisms of antiviral innate immunity by CMV will help investigators identify new therapeutic targets and develop vaccines against CMV infection.
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Affiliation(s)
- Shuang Li
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Yuanyang Xie
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Changyin Yu
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, China.
- The Collaborative Innovation Center of Tissue Damage Repair and Regeneration Medicine, Zunyi Medical University, Zunyi, China.
| | - Chunfu Zheng
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB, Canada.
| | - Zucai Xu
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, China.
- The Collaborative Innovation Center of Tissue Damage Repair and Regeneration Medicine, Zunyi Medical University, Zunyi, China.
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5
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Yin J, Yu Y, Huang X, Chan FKM. Necroptosis in immunity, tissue homeostasis, and cancer. Curr Opin Immunol 2024; 89:102455. [PMID: 39167896 DOI: 10.1016/j.coi.2024.102455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 08/06/2024] [Indexed: 08/23/2024]
Abstract
Immune and tissue homeostasis is achieved through balancing signals that regulate cell survival, proliferation, and cell death. Recent studies indicate that certain cell death programs can stimulate inflammation and are often referred as 'immunogenic cell death' (ICD). ICD is a double-edged sword that can confer protection against pathogen infection but also cause tissue damage. Necroptosis is a key ICD module that has been shown to participate in host defense against pathogen infection, tissue homeostasis, and cancer response to immunotherapy. Here, we will review recent findings on the regulation of necroptosis signaling and its role in pathogen infection, tissue homeostasis, and cancer.
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Affiliation(s)
| | - Yuqiang Yu
- Department of Cardiology of the Second Affiliated Hospital, China; State Key Laboratory of Transvascular Implantation Devices, Heart Regeneration and Repair Key Laboratory of Zhejiang Province, China
| | | | - Francis K-M Chan
- Department of Cardiology of the Second Affiliated Hospital, China; State Key Laboratory of Transvascular Implantation Devices, Heart Regeneration and Repair Key Laboratory of Zhejiang Province, China; Liangzhu Laboratory, China; Zhejiang University School of Medicine, 1369 West Wenyi Road, Hangzhou 311121, China.
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6
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Chiou S, Al-Ani AH, Pan Y, Patel KM, Kong IY, Whitehead LW, Light A, Young SN, Barrios M, Sargeant C, Rajasekhar P, Zhu L, Hempel A, Lin A, Rickard JA, Hall C, Gangatirkar P, Yip RK, Cawthorne W, Jacobsen AV, Horne CR, Martin KR, Ioannidis LJ, Hansen DS, Day J, Wicks IP, Law C, Ritchie ME, Bowden R, Hildebrand JM, O'Reilly LA, Silke J, Giulino-Roth L, Tsui E, Rogers KL, Hawkins ED, Christensen B, Murphy JM, Samson AL. An immunohistochemical atlas of necroptotic pathway expression. EMBO Mol Med 2024; 16:1717-1749. [PMID: 38750308 PMCID: PMC11250867 DOI: 10.1038/s44321-024-00074-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 04/19/2024] [Accepted: 04/22/2024] [Indexed: 06/12/2024] Open
Abstract
Necroptosis is a lytic form of regulated cell death reported to contribute to inflammatory diseases of the gut, skin and lung, as well as ischemic-reperfusion injuries of the kidney, heart and brain. However, precise identification of the cells and tissues that undergo necroptotic cell death in vivo has proven challenging in the absence of robust protocols for immunohistochemical detection. Here, we provide automated immunohistochemistry protocols to detect core necroptosis regulators - Caspase-8, RIPK1, RIPK3 and MLKL - in formalin-fixed mouse and human tissues. We observed surprising heterogeneity in protein expression within tissues, whereby short-lived immune barrier cells were replete with necroptotic effectors, whereas long-lived cells lacked RIPK3 or MLKL expression. Local changes in the expression of necroptotic effectors occurred in response to insults such as inflammation, dysbiosis or immune challenge, consistent with necroptosis being dysregulated in disease contexts. These methods will facilitate the precise localisation and evaluation of necroptotic signaling in vivo.
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Affiliation(s)
- Shene Chiou
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- University of Melbourne, Parkville, Australia
| | - Aysha H Al-Ani
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- University of Melbourne, Parkville, Australia
- Royal Melbourne Hospital, Parkville, Australia
| | - Yi Pan
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
| | - Komal M Patel
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
| | - Isabella Y Kong
- Pediatric Hematology/Oncology, Weill Cornell Medical College, New York, USA
| | - Lachlan W Whitehead
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- University of Melbourne, Parkville, Australia
| | - Amanda Light
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
| | - Samuel N Young
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
| | - Marilou Barrios
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- University of Melbourne, Parkville, Australia
| | - Callum Sargeant
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- University of Melbourne, Parkville, Australia
| | - Pradeep Rajasekhar
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- University of Melbourne, Parkville, Australia
| | - Leah Zhu
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
| | - Anne Hempel
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
| | - Ann Lin
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
| | - James A Rickard
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- Austin Hospital, Heidelberg, Australia
| | - Cathrine Hall
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
| | | | - Raymond Kh Yip
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- University of Melbourne, Parkville, Australia
| | - Wayne Cawthorne
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- University of Melbourne, Parkville, Australia
| | - Annette V Jacobsen
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- University of Melbourne, Parkville, Australia
| | - Christopher R Horne
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- University of Melbourne, Parkville, Australia
| | - Katherine R Martin
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- University of Melbourne, Parkville, Australia
| | - Lisa J Ioannidis
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- University of Melbourne, Parkville, Australia
| | - Diana S Hansen
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- University of Melbourne, Parkville, Australia
- Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Australia
| | - Jessica Day
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- University of Melbourne, Parkville, Australia
- Royal Melbourne Hospital, Parkville, Australia
| | - Ian P Wicks
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- University of Melbourne, Parkville, Australia
| | - Charity Law
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- University of Melbourne, Parkville, Australia
| | - Matthew E Ritchie
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- University of Melbourne, Parkville, Australia
| | - Rory Bowden
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- University of Melbourne, Parkville, Australia
| | - Joanne M Hildebrand
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- University of Melbourne, Parkville, Australia
| | - Lorraine A O'Reilly
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- University of Melbourne, Parkville, Australia
| | - John Silke
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- University of Melbourne, Parkville, Australia
| | - Lisa Giulino-Roth
- Pediatric Hematology/Oncology, Weill Cornell Medical College, New York, USA
| | - Ellen Tsui
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
| | - Kelly L Rogers
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- University of Melbourne, Parkville, Australia
| | - Edwin D Hawkins
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- University of Melbourne, Parkville, Australia
| | - Britt Christensen
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- University of Melbourne, Parkville, Australia
- Royal Melbourne Hospital, Parkville, Australia
| | - James M Murphy
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.
- University of Melbourne, Parkville, Australia.
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia.
| | - André L Samson
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.
- University of Melbourne, Parkville, Australia.
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7
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Chandra P, Patra U, Mukhopadhyay U, Mukherjee A, Halder P, Koley H, Chawla-Sarkar M. Rotavirus non-structural protein 4 usurps host cellular RIPK1-RIPK3 complex to induce MLKL-dependent necroptotic cell death. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119745. [PMID: 38719029 DOI: 10.1016/j.bbamcr.2024.119745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 04/11/2024] [Accepted: 04/16/2024] [Indexed: 05/14/2024]
Abstract
The dynamic interface between invading viral pathogens and programmed cell death (PCD) of the host is a finely regulated process. Host cellular demise at the end of the viral life cycle ensures the release of progeny virions to initiate new infection cycles. Rotavirus (RV), a diarrheagenic virus with double-stranded RNA genome, has been reported to trigger different types of PCD such as apoptosis and pyroptosis in a highly regulated way to successfully disseminate progeny virions. Recently our lab also showed that induction of MLKL-driven programmed necroptosis by RV. However, the host cellular machinery involved in RV-induced necroptosis and the upstream viral trigger responsible for it remained unaddressed. In the present study, the signalling upstream of MLKL-driven necroptosis has been delineated where the involvement of Receptor interacting serine/threonine kinase 3 (RIPK3) and 1 (RIPK1) from the host side and RV non-structural protein 4 (NSP4) as the viral trigger for necroptosis has been shown. Interestingly, RV-NSP4 was found to be an integral component of the necrosome complex by interacting with RIPK1, thereby bypassing the requirement of RIPK1 kinase activity. Subsequently, NSP4-driven elevated cytosolic Ca2+ concentration and Ca2+-binding to NSP4 lead further to RHIM domain-dependent RIPK1-RIPK3 interaction, RIPK3-dependent MLKL phosphorylation, and eventual necroptosis. Overall, this study presents the interplay between RV-NSP4 and the host cellular necrosome complex to induce necroptotic death of host cells.
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Affiliation(s)
- Pritam Chandra
- Division of Virology, ICMR-National Institute of Cholera and Enteric Diseases, Kolkata, West Bengal, India
| | - Upayan Patra
- Institute of Biochemistry II, Faculty of Medicine, Goethe University, Frankfurt, Germany
| | - Urbi Mukhopadhyay
- European Molecular Biology Laboratory, 71 Av. Des Martyrs, 38000 Grenoble, France
| | - Arpita Mukherjee
- Division of Virology, ICMR-National Institute of Cholera and Enteric Diseases, Kolkata, West Bengal, India
| | - Prolay Halder
- Division of Bacteriology, ICMR-National Institute of Cholera and Enteric Diseases, Kolkata, West Bengal, India
| | - Hemanta Koley
- Division of Bacteriology, ICMR-National Institute of Cholera and Enteric Diseases, Kolkata, West Bengal, India
| | - Mamta Chawla-Sarkar
- Division of Virology, ICMR-National Institute of Cholera and Enteric Diseases, Kolkata, West Bengal, India.
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8
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Li H, Fletcher-Etherington A, Hunter LM, Keshri S, Fielding CA, Nightingale K, Ravenhill B, Nobre L, Potts M, Antrobus R, Crump CM, Rubinsztein DC, Stanton RJ, Weekes MP. Human cytomegalovirus degrades DMXL1 to inhibit autophagy, lysosomal acidification, and viral assembly. Cell Host Microbe 2024; 32:466-478.e11. [PMID: 38479395 DOI: 10.1016/j.chom.2024.02.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 01/10/2024] [Accepted: 02/20/2024] [Indexed: 04/13/2024]
Abstract
Human cytomegalovirus (HCMV) is an important human pathogen that regulates host immunity and hijacks host compartments, including lysosomes, to assemble virions. We combined a quantitative proteomic analysis of HCMV infection with a database of proteins involved in vacuolar acidification, revealing Dmx-like protein-1 (DMXL1) as the only protein that acidifies vacuoles yet is degraded by HCMV. Systematic comparison of viral deletion mutants reveals the uncharacterized 7 kDa US33A protein as necessary and sufficient for DMXL1 degradation, which occurs via recruitment of the E3 ubiquitin ligase Kip1 ubiquitination-promoting complex (KPC). US33A-mediated DMXL1 degradation inhibits lysosome acidification and autophagic cargo degradation. Formation of the virion assembly compartment, which requires lysosomes, occurs significantly later with US33A-expressing virus infection, with reduced viral replication. These data thus identify a viral strategy for cellular remodeling, with the potential to employ US33A in therapies for viral infection or rheumatic conditions, in which inhibition of lysosome acidification can attenuate disease.
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Affiliation(s)
- Hanqi Li
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK; Department of Medicine, University of Cambridge, Hills Road, Cambridge CB2 2QQ, UK
| | - Alice Fletcher-Etherington
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK; Department of Medicine, University of Cambridge, Hills Road, Cambridge CB2 2QQ, UK
| | - Leah M Hunter
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK; Department of Medicine, University of Cambridge, Hills Road, Cambridge CB2 2QQ, UK
| | - Swati Keshri
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK; UK Dementia Institute, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Ceri A Fielding
- Cardiff University School of Medicine, Division of Infection and Immunity, Henry Wellcome Building, Heath Park, Cardiff CF14 4XN, UK
| | - Katie Nightingale
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK; Department of Medicine, University of Cambridge, Hills Road, Cambridge CB2 2QQ, UK
| | - Benjamin Ravenhill
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK; Department of Medicine, University of Cambridge, Hills Road, Cambridge CB2 2QQ, UK
| | - Luis Nobre
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK; Department of Medicine, University of Cambridge, Hills Road, Cambridge CB2 2QQ, UK
| | - Martin Potts
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK; Department of Medicine, University of Cambridge, Hills Road, Cambridge CB2 2QQ, UK
| | - Robin Antrobus
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK; Department of Medicine, University of Cambridge, Hills Road, Cambridge CB2 2QQ, UK
| | - Colin M Crump
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge, UK
| | - David C Rubinsztein
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK; UK Dementia Institute, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Richard J Stanton
- Cardiff University School of Medicine, Division of Infection and Immunity, Henry Wellcome Building, Heath Park, Cardiff CF14 4XN, UK
| | - Michael P Weekes
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK.
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9
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Hunter LM, Kite J, Fletcher-Etherington A, Nightingale K, Nobre L, Antrobus R, Fielding CA, Stanton RJ, Weekes MP. HCMV US2 co-opts TRC8 to degrade the endoplasmic reticulum-resident protein LMAN2L. J Gen Virol 2024; 105:001980. [PMID: 38687323 PMCID: PMC11083459 DOI: 10.1099/jgv.0.001980] [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: 02/06/2024] [Accepted: 04/12/2024] [Indexed: 05/02/2024] Open
Abstract
The human cytomegalovirus (HCMV) pUS2 glycoprotein exploits the host's endoplasmic reticulum (ER)-associated degradation (ERAD) pathway to degrade major histocompatibility complex class I (MHC-I) and prevent antigen presentation. Beyond MHC-I, pUS2 has been shown to target a range of cellular proteins for degradation, preventing their cell surface expression. Here we have identified a novel pUS2 target, ER-resident protein lectin mannose binding 2 like (LMAN2L). pUS2 expression was both necessary and sufficient for the downregulation of LMAN2L, which was dependent on the cellular E3 ligase TRC8. Given the hypothesized role of LMAN2L in the trafficking of glycoproteins, we employed proteomic plasma membrane profiling to measure LMAN2L-dependent changes at the cell surface. A known pUS2 target, integrin alpha-6 (ITGA6), was downregulated from the surface of LMAN2L-deficient cells, but not other integrins. Overall, these results suggest a novel strategy of pUS2-mediated protein degradation whereby pUS2 targets LMAN2L to impair trafficking of ITGA6. Given that pUS2 can directly target other integrins, we propose that this single viral protein may exhibit both direct and indirect mechanisms to downregulate key cell surface molecules.
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Affiliation(s)
- Leah M. Hunter
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK
- Department of Medicine, University of Cambridge, Hills Road, Cambridge, CB2 2QQ, UK
| | - Joanne Kite
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK
- Department of Medicine, University of Cambridge, Hills Road, Cambridge, CB2 2QQ, UK
| | - Alice Fletcher-Etherington
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK
- Department of Medicine, University of Cambridge, Hills Road, Cambridge, CB2 2QQ, UK
| | - Katie Nightingale
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK
- Department of Medicine, University of Cambridge, Hills Road, Cambridge, CB2 2QQ, UK
| | - Luis Nobre
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK
- Department of Medicine, University of Cambridge, Hills Road, Cambridge, CB2 2QQ, UK
| | - Robin Antrobus
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK
- Department of Medicine, University of Cambridge, Hills Road, Cambridge, CB2 2QQ, UK
| | - Ceri A. Fielding
- Cardiff University School of Medicine, Division of Infection and Immunity, Henry Wellcome Building, Heath Park, Cardiff CF14 4XN, UK
| | - Richard J. Stanton
- Cardiff University School of Medicine, Division of Infection and Immunity, Henry Wellcome Building, Heath Park, Cardiff CF14 4XN, UK
| | - Michael P. Weekes
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK
- Department of Medicine, University of Cambridge, Hills Road, Cambridge, CB2 2QQ, UK
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10
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Heusel AT, Rapp S, Stamminger T, Scherer M. IE1 of Human Cytomegalovirus Inhibits Necroptotic Cell Death via Direct and Indirect Modulation of the Necrosome Complex. Viruses 2024; 16:290. [PMID: 38400065 PMCID: PMC10893529 DOI: 10.3390/v16020290] [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: 12/22/2023] [Revised: 01/29/2024] [Accepted: 02/08/2024] [Indexed: 02/25/2024] Open
Abstract
Programmed necrosis is an integral part of intrinsic immunity, serving to combat invading pathogens and restricting viral dissemination. The orchestration of necroptosis relies on a precise interplay within the necrosome complex, which consists of RIPK1, RIPK3 and MLKL. Human cytomegalovirus (HCMV) has been found to counteract the execution of necroptosis during infection. In this study, we identify the immediate-early 1 (IE1) protein as a key antagonist of necroptosis during HCMV infection. Infection data obtained in a necroptosis-sensitive cell culture system revealed a robust regulation of post-translational modifications (PTMs) of the necrosome complex as well as the importance of IE1 expression for an effective counteraction of necroptosis. Interaction analyses unveiled an association of IE1 and RIPK3, which occurs in an RHIM-domain independent manner. We propose that this interaction manipulates the PTMs of RIPK3 by promoting its ubiquitination. Furthermore, IE1 was found to exert an indirect activity by modulating the levels of MLKL via antagonizing its interferon-mediated upregulation. Overall, we claim that IE1 performs a broad modulation of innate immune signaling to impede the execution of necroptotic cell death, thereby generating a favorable environment for efficient viral replication.
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Affiliation(s)
| | | | - Thomas Stamminger
- Institute of Virology, Ulm University Medical Center, 89081 Ulm, Germany; (A.T.H.); (S.R.)
| | - Myriam Scherer
- Institute of Virology, Ulm University Medical Center, 89081 Ulm, Germany; (A.T.H.); (S.R.)
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11
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Deng Y, Ostermann E, Brune W. A cytomegalovirus inflammasome inhibitor reduces proinflammatory cytokine release and pyroptosis. Nat Commun 2024; 15:786. [PMID: 38278864 PMCID: PMC10817922 DOI: 10.1038/s41467-024-45151-z] [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: 04/24/2023] [Accepted: 01/17/2024] [Indexed: 01/28/2024] Open
Abstract
In response to viral infection, cells can initiate programmed cell death (PCD), leading to a reduction in the release of viral progeny. Viruses have therefore evolved specific mechanisms to curb PCD. Cytomegaloviruses (CMVs) are sophisticated manipulators of cellular defenses and encode potent inhibitors of apoptosis and necroptosis. However, a CMV inhibitor of pyroptosis has not been clearly identified and characterized. Here we identify the mouse cytomegalovirus M84 protein as an inhibitor of pyroptosis and proinflammatory cytokine release. M84 interacts with the pyrin domain of AIM2 and ASC to inhibit inflammasome assembly. It thereby prevents Caspase-1-mediated activation of interleukin 1β (IL-1β), IL-18, and Gasdermin D. Growth attenuation of an M84-deficient MCMV in macrophages is rescued by knockout of either Aim2 or Asc or by treatment with a Caspase-1 inhibitor, and its attenuation in infected mice is partially rescued in Asc knockout mice. Thus, viral inhibition of the inflammasome-pyroptosis pathway is important to promote viral replication in vivo.
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Affiliation(s)
- Yingqi Deng
- Leibniz Institute of Virology (LIV), Hamburg, Germany
| | | | - Wolfram Brune
- Leibniz Institute of Virology (LIV), Hamburg, Germany.
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12
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Ren J, Yu P, Liu S, Li R, Niu X, Chen Y, Zhang Z, Zhou F, Zhang L. Deubiquitylating Enzymes in Cancer and Immunity. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2303807. [PMID: 37888853 PMCID: PMC10754134 DOI: 10.1002/advs.202303807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Revised: 08/30/2023] [Indexed: 10/28/2023]
Abstract
Deubiquitylating enzymes (DUBs) maintain relative homeostasis of the cellular ubiquitome by removing the post-translational modification ubiquitin moiety from substrates. Numerous DUBs have been demonstrated specificity for cleaving a certain type of ubiquitin linkage or positions within ubiquitin chains. Moreover, several DUBs perform functions through specific protein-protein interactions in a catalytically independent manner, which further expands the versatility and complexity of DUBs' functions. Dysregulation of DUBs disrupts the dynamic equilibrium of ubiquitome and causes various diseases, especially cancer and immune disorders. This review summarizes the Janus-faced roles of DUBs in cancer including proteasomal degradation, DNA repair, apoptosis, and tumor metastasis, as well as in immunity involving innate immune receptor signaling and inflammatory and autoimmune disorders. The prospects and challenges for the clinical development of DUB inhibitors are further discussed. The review provides a comprehensive understanding of the multi-faced roles of DUBs in cancer and immunity.
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Affiliation(s)
- Jiang Ren
- The Eighth Affiliated HospitalSun Yat‐sen UniversityShenzhen518033P. R. China
| | - Peng Yu
- Zhongshan Institute for Drug DiscoveryShanghai Institute of Materia MedicaChinese Academy of SciencesZhongshanGuangdongP. R. China
| | - Sijia Liu
- International Biomed‐X Research CenterSecond Affiliated Hospital of Zhejiang University School of MedicineZhejiang UniversityHangzhouP. R. China
- Key Laboratory of Precision Diagnosis and Treatment for Hepatobiliary and Pancreatic Tumor of Zhejiang ProvinceHangzhou310058China
| | - Ran Li
- The Eighth Affiliated HospitalSun Yat‐sen UniversityShenzhen518033P. R. China
| | - Xin Niu
- MOE Laboratory of Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling NetworkLife Sciences InstituteZhejiang UniversityHangzhou310058P. R. China
| | - Yan Chen
- The Eighth Affiliated HospitalSun Yat‐sen UniversityShenzhen518033P. R. China
| | - Zhenyu Zhang
- Department of NeurosurgeryThe First Affiliated Hospital of Zhengzhou UniversityZhengzhouHenan450003P. R. China
| | - Fangfang Zhou
- Institutes of Biology and Medical ScienceSoochow UniversitySuzhou215123P. R. China
| | - Long Zhang
- The Eighth Affiliated HospitalSun Yat‐sen UniversityShenzhen518033P. R. China
- International Biomed‐X Research CenterSecond Affiliated Hospital of Zhejiang University School of MedicineZhejiang UniversityHangzhouP. R. China
- MOE Laboratory of Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling NetworkLife Sciences InstituteZhejiang UniversityHangzhou310058P. R. China
- Cancer CenterZhejiang UniversityHangzhouZhejiang310058P. R. China
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13
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Meng Y, Garnish SE, Davies KA, Black KA, Leis AP, Horne CR, Hildebrand JM, Hoblos H, Fitzgibbon C, Young SN, Dite T, Dagley LF, Venkat A, Kannan N, Koide A, Koide S, Glukhova A, Czabotar PE, Murphy JM. Phosphorylation-dependent pseudokinase domain dimerization drives full-length MLKL oligomerization. Nat Commun 2023; 14:6804. [PMID: 37884510 PMCID: PMC10603135 DOI: 10.1038/s41467-023-42255-w] [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: 06/23/2023] [Accepted: 10/04/2023] [Indexed: 10/28/2023] Open
Abstract
The necroptosis pathway is a lytic, pro-inflammatory mode of cell death that is widely implicated in human disease, including renal, pulmonary, gut and skin inflammatory pathologies. The precise mechanism of the terminal steps in the pathway, where the RIPK3 kinase phosphorylates and triggers a conformation change and oligomerization of the terminal pathway effector, MLKL, are only emerging. Here, we structurally identify RIPK3-mediated phosphorylation of the human MLKL activation loop as a cue for MLKL pseudokinase domain dimerization. MLKL pseudokinase domain dimerization subsequently drives formation of elongated homotetramers. Negative stain electron microscopy and modelling support nucleation of the MLKL tetramer assembly by a central coiled coil formed by the extended, ~80 Å brace helix that connects the pseudokinase and executioner four-helix bundle domains. Mutational data assert MLKL tetramerization as an essential prerequisite step to enable the release and reorganization of four-helix bundle domains for membrane permeabilization and cell death.
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Affiliation(s)
- Yanxiang Meng
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Sarah E Garnish
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Katherine A Davies
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Katrina A Black
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Andrew P Leis
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Christopher R Horne
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Joanne M Hildebrand
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Hanadi Hoblos
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Cheree Fitzgibbon
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Samuel N Young
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
| | - Toby Dite
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Laura F Dagley
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Aarya Venkat
- Institute of Bioinformatics, University of Georgia, Athens, GA, 30602, USA
| | - Natarajan Kannan
- Institute of Bioinformatics, University of Georgia, Athens, GA, 30602, USA
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, 30602, USA
| | - Akiko Koide
- Perlmutter Cancer Center, New York University Langone Health, New York, NY, 10016, USA
- Department of Medicine, New York University School of Medicine, New York, NY, 10016, USA
| | - Shohei Koide
- Perlmutter Cancer Center, New York University Langone Health, New York, NY, 10016, USA
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, 10016, USA
| | - Alisa Glukhova
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
- Department of Biochemistry and Pharmacology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Peter E Czabotar
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia.
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia.
| | - James M Murphy
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia.
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia.
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia.
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14
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Cheung J, Remiszewski S, Chiang LW, Ahmad E, Pal M, Rahman SA, Nikolovska-Coleska Z, Chan GC. Inhibition of SIRT2 promotes death of human cytomegalovirus-infected peripheral blood monocytes via apoptosis and necroptosis. Antiviral Res 2023; 217:105698. [PMID: 37562606 DOI: 10.1016/j.antiviral.2023.105698] [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: 05/24/2023] [Revised: 08/02/2023] [Accepted: 08/04/2023] [Indexed: 08/12/2023]
Abstract
Peripheral blood monocytes are the cells predominantly responsible for systemic dissemination of human cytomegalovirus (HCMV) and a significant cause of morbidity and mortality in immunocompromised patients. HCMV establishes a silent/quiescent infection in monocytes, which is defined by the lack of viral replication and lytic gene expression. The absence of replication shields the virus within infected monocytes from the current available antiviral drugs that are designed to suppress active replication. Our previous work has shown that HCMV stimulates a noncanonical phosphorylation of Akt and the subsequent upregulation of a distinct subset of prosurvival proteins in normally short-lived monocytes. In this study, we found that SIRT2 activity is required for the unique activation profile of Akt induced within HCMV-infected monocytes. Importantly, both therapeutic and prophylactic treatment with a novel SIRT2 inhibitor, FLS-379, promoted death of infected monocytes via both the apoptotic and necroptotic cell death pathways. Mechanistically, SIRT2 inhibition reduced expression of Mcl-1, an Akt-dependent antiapoptotic Bcl-2 family member, and enhanced activation of MLKL, the executioner kinase of necroptosis. We have previously reported HCMV to block necroptosis by stimulating cellular autophagy. Here, we additionally demonstrate that inhibition of SIRT2 suppressed Akt-dependent HCMV-induced autophagy leading to necroptosis of infected monocytes. Overall, our data show that SIRT2 inhibition can simultaneously promote death of quiescently infected monocytes by two distinct death pathways, apoptosis and necroptosis, which may be vital for limiting viral dissemination to peripheral organs in immunosuppressed patients.
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Affiliation(s)
- Jennifer Cheung
- Department of Microbiology & Immunology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Stacy Remiszewski
- Evrys Bio, LLC, Pennsylvania Biotechnology Center, Doylestown, PA, 18902, USA
| | - Lillian W Chiang
- Evrys Bio, LLC, Pennsylvania Biotechnology Center, Doylestown, PA, 18902, USA
| | - Ejaz Ahmad
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Mohan Pal
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Sm Ashikur Rahman
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Zaneta Nikolovska-Coleska
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA; Rogel Cancer Center, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Gary C Chan
- Department of Microbiology & Immunology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA.
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15
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Yu C, He S, Zhu W, Ru P, Ge X, Govindasamy K. Human cytomegalovirus in cancer: the mechanism of HCMV-induced carcinogenesis and its therapeutic potential. Front Cell Infect Microbiol 2023; 13:1202138. [PMID: 37424781 PMCID: PMC10327488 DOI: 10.3389/fcimb.2023.1202138] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 06/08/2023] [Indexed: 07/11/2023] Open
Abstract
Cancer is one of the leading causes of death worldwide. Human cytomegalovirus (HCMV), a well-studied herpesvirus, has been implicated in malignancies derived from breast, colorectal muscle, brain, and other cancers. Intricate host-virus interactions are responsible for the cascade of events that have the potential to result in the transformed phenotype of normal cells. The HCMV genome contains oncogenes that may initiate these types of cancers, and although the primary HCMV infection is usually asymptomatic, the virus remains in the body in a latent or persistent form. Viral reactivation causes severe health issues in immune-compromised individuals, including cancer patients, organ transplants, and AIDS patients. This review focuses on the immunologic mechanisms and molecular mechanisms of HCMV-induced carcinogenesis, methods of HCMV treatment, and other studies. Studies show that HCMV DNA and virus-specific antibodies are present in many types of cancers, implicating HCMV as an important player in cancer progression. Importantly, many clinical trials have been initiated to exploit HCMV as a therapeutic target for the treatment of cancer, particularly in immunotherapy strategies in the treatment of breast cancer and glioblastoma patients. Taken together, these findings support a link between HCMV infections and cellular growth that develops into cancer. More importantly, HCMV is the leading cause of birth defects in newborns, and infection with HCMV is responsible for abortions in pregnant women.
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Affiliation(s)
- Chuan Yu
- Animal Diseases and Public Health Engineering Research Center of Henan Province, Luoyang Polytechnic, Luoyang, Henan, China
| | - Suna He
- Department of Pharmaceutical Sciences, School of Basic Medical Sciences, Henan University of Science and Technology, Luoyang, Henan, China
| | - Wenwen Zhu
- Animal Diseases and Public Health Engineering Research Center of Henan Province, Luoyang Polytechnic, Luoyang, Henan, China
| | - Penghui Ru
- Animal Diseases and Public Health Engineering Research Center of Henan Province, Luoyang Polytechnic, Luoyang, Henan, China
| | - Xuemei Ge
- School of Light Industry and Food Engineering, Nanjing Forestry University, Nanjing, Jiangsu, China
| | - Kavitha Govindasamy
- School of Arts and Science, Rutgers, the State University of New Jersey, Newark, NJ, United States
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16
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Bachman LO, Zwezdaryk KJ. Targeting the Host Mitochondria as a Novel Human Cytomegalovirus Antiviral Strategy. Viruses 2023; 15:v15051083. [PMID: 37243170 DOI: 10.3390/v15051083] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 04/20/2023] [Accepted: 04/26/2023] [Indexed: 05/28/2023] Open
Abstract
Human cytomegalovirus (HCMV) exploits host mitochondrial function to promote viral replication. HCMV gene products have been described to directly interact and alter functional or structural aspects of host mitochondria. Current antivirals against HCMV, such as ganciclovir and letermovir, are designed against viral targets. Concerns with the current antivirals include toxicity and viral resistance. Targeting host mitochondrial function is a promising alternative or complimentary antiviral approach as (1) drugs targeting host mitochondrial function interact with host targets, minimizing viral resistance, and (2) host mitochondrial metabolism plays key roles in HCMV replication. This review describes how HCMV alters mitochondrial function and highlights pharmacological targets that can be exploited for novel antiviral development.
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Affiliation(s)
- Lauryn O Bachman
- Department of Cell and Molecular Biology, Tulane University School of Science and Engineering, New Orleans, LA 70112, USA
| | - Kevin J Zwezdaryk
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA 70112, USA
- Tulane Brain Institute, Tulane University School of Medicine, New Orleans, LA 70112, USA
- Tulane Center for Aging, Tulane University School of Medicine, New Orleans, LA 70112, USA
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17
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Yadav SK, Gawargi FI, Hasan MH, Tandon R, Upton JW, Mishra PK. Differential effects of CMV infection on the viability of cardiac cells. Cell Death Discov 2023; 9:111. [PMID: 37012234 PMCID: PMC10070260 DOI: 10.1038/s41420-023-01408-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 03/20/2023] [Accepted: 03/22/2023] [Indexed: 04/05/2023] Open
Abstract
Cytomegalovirus (CMV) is a widely prevalent herpesvirus that reaches seroprevalence rates of up to 95% in several parts of the world. The majority of CMV infections are asymptomatic, albeit they have severe detrimental effects on immunocompromised individuals. Congenital CMV infection is a leading cause of developmental abnormalities in the USA. CMV infection is a significant risk factor for cardiovascular diseases in individuals of all ages. Like other herpesviruses, CMV regulates cell death for its replication and establishes and maintains a latent state in the host. Although CMV-mediated regulation of cell death is reported by several groups, it is unknown how CMV infection affects necroptosis and apoptosis in cardiac cells. Here, we infected primary cardiomyocytes, the contractile cells in the heart, and primary cardiac fibroblasts with wild-type and cell-death suppressor deficient mutant CMVs to determine how CMV regulates necroptosis and apoptosis in cardiac cells. Our results reveal that CMV infection prevents TNF-induced necroptosis in cardiomyocytes; however, the opposite phenotype is observed in cardiac fibroblasts. CMV infection also suppresses inflammation, reactive oxygen species (ROS) generation, and apoptosis in cardiomyocytes. Furthermore, CMV infection improves mitochondrial biogenesis and viability in cardiomyocytes. We conclude that CMV infection differentially affects the viability of cardiac cells.
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Affiliation(s)
- Santosh K Yadav
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Flobater I Gawargi
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Mohammad H Hasan
- Department of Cell and Molecular Biology, Center for Immunology and Microbial Research, University of Mississippi Medical Center, Jackson, MS, USA
| | - Ritesh Tandon
- Department of Cell and Molecular Biology, Center for Immunology and Microbial Research, University of Mississippi Medical Center, Jackson, MS, USA
- Department of Medicine, University of Mississippi Medical Center, Jackson, MS, USA
| | - Jason W Upton
- Department of Biological Sciences, Auburn University, Alabama, AL, USA
| | - Paras K Mishra
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, USA.
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18
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Gardner C, Davies KA, Zhang Y, Brzozowski M, Czabotar PE, Murphy JM, Lessene G. From (Tool)Bench to Bedside: The Potential of Necroptosis Inhibitors. J Med Chem 2023; 66:2361-2385. [PMID: 36781172 PMCID: PMC9969410 DOI: 10.1021/acs.jmedchem.2c01621] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Necroptosis is a regulated caspase-independent form of necrotic cell death that results in an inflammatory phenotype. This process contributes profoundly to the pathophysiology of numerous neurodegenerative, cardiovascular, infectious, malignant, and inflammatory diseases. Receptor-interacting protein kinase 1 (RIPK1), RIPK3, and the mixed lineage kinase domain-like protein (MLKL) pseudokinase have been identified as the key components of necroptosis signaling and are the most promising targets for therapeutic intervention. Here, we review recent developments in the field of small-molecule inhibitors of necroptosis signaling, provide guidelines for their use as chemical probes to study necroptosis, and assess the therapeutic challenges and opportunities of such inhibitors in the treatment of a range of clinical indications.
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Affiliation(s)
- Christopher
R. Gardner
- The
Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia,Department
of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Katherine A. Davies
- The
Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia,Department
of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Ying Zhang
- The
Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia,Department
of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Martin Brzozowski
- The
Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia,Department
of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Peter E. Czabotar
- The
Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia,Department
of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - James M. Murphy
- The
Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia,Department
of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Guillaume Lessene
- The
Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia,Department
of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia,Department
of Pharmacology and Therapeutics, University
of Melbourne, Parkville, VIC 3052, Australia,Email;
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19
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Albarnaz JD, Weekes MP. Proteomic analysis of antiviral innate immunity. Curr Opin Virol 2023; 58:101291. [PMID: 36529073 DOI: 10.1016/j.coviro.2022.101291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 10/03/2022] [Accepted: 11/17/2022] [Indexed: 12/23/2022]
Abstract
The capacity of host cells to detect and restrict an infecting virus rests on an array of cell-autonomous antiviral effectors and innate immune receptors that can trigger inflammatory processes at tissue and organismal levels. Dynamic changes in protein abundance, subcellular localisation, post-translational modifications and interactions with other biomolecules govern these processes. Proteomics is therefore an ideal experimental tool to discover novel mechanisms of host antiviral immunity. Additional information can be gleaned both about host and virus by systematic analysis of viral immune evasion strategies. In this review, we summarise recent advances in proteomic technologies and their application to antiviral innate immunity.
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Affiliation(s)
- Jonas D Albarnaz
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, CB2 0XY Cambridge, UK
| | - Michael P Weekes
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, CB2 0XY Cambridge, UK.
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20
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Mocarski ES. Programmed Necrosis in Host Defense. Curr Top Microbiol Immunol 2023; 442:1-40. [PMID: 37563336 DOI: 10.1007/82_2023_264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
Host control over infectious disease relies on the ability of cells in multicellular organisms to detect and defend against pathogens to prevent disease. Evolution affords mammals with a wide variety of independent immune mechanisms to control or eliminate invading infectious agents. Many pathogens acquire functions to deflect these immune mechanisms and promote infection. Following successful invasion of a host, cell autonomous signaling pathways drive the production of inflammatory cytokines, deployment of restriction factors and induction of cell death. Combined, these innate immune mechanisms attract dendritic cells, neutrophils and macrophages as well as innate lymphoid cells such as natural killer cells that all help control infection. Eventually, the development of adaptive pathogen-specific immunity clears infection and provides immune memory of the encounter. For obligate intracellular pathogens such as viruses, diverse cell death pathways make a pivotal contribution to early control by eliminating host cells before progeny are produced. Pro-apoptotic caspase-8 activity (along with caspase-10 in humans) executes extrinsic apoptosis, a nonlytic form of cell death triggered by TNF family death receptors (DRs). Over the past two decades, alternate extrinsic apoptosis and necroptosis outcomes have been described. Programmed necrosis, or necroptosis, occurs when receptor interacting protein kinase 3 (RIPK3) activates mixed lineage kinase-like (MLKL), causing cell leakage. Thus, activation of DRs, toll-like receptors (TLRs) or pathogen sensor Z-nucleic acid binding protein 1 (ZBP1) initiates apoptosis as well as necroptosis if not blocked by virus-encoded inhibitors. Mammalian cell death pathways are blocked by herpesvirus- and poxvirus-encoded cell death suppressors. Growing evidence has revealed the importance of Z-nucleic acid sensor, ZBP1, in the cell autonomous recognition of both DNA and RNA virus infection. This volume will explore the detente between viruses and cells to manage death machinery and avoid elimination to support dissemination within the host animal.
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Affiliation(s)
- Edward S Mocarski
- Robert W. Woodruff Professor Emeritus, Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA, 30322, USA.
- Professor Emeritus, Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, 94305, USA.
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21
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Lawson CA, Titus DJ, Koehler HS. Approaches to Evaluating Necroptosis in Virus-Infected Cells. Subcell Biochem 2023; 106:37-75. [PMID: 38159223 DOI: 10.1007/978-3-031-40086-5_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
The immune system functions to protect the host from pathogens. To counter host defense mechanisms, pathogens have developed unique strategies to evade detection or restrict host immune responses. Programmed cell death is a major contributor to the multiple host responses that help to eliminate infected cells for obligate intracellular pathogens like viruses. Initiation of programmed cell death pathways during the early stages of viral infections is critical for organismal survival as it restricts the virus from replicating and serves to drive antiviral inflammation immune recruitment through the release of damage-associated molecular patterns (DAMPs) from the dying cell. Necroptosis has been implicated as a critical programmed cell death pathway in a diverse set of diseases and pathological conditions including acute viral infections. This cell death pathway occurs when certain host sensors are triggered leading to the downstream induction of mixed-lineage kinase domain-like protein (MLKL). MLKL induction leads to cytoplasmic membrane disruption and subsequent cellular destruction with the release of DAMPs. As the role of this cell death pathway in human disease becomes apparent, methods identifying necroptosis patterns and outcomes will need to be further developed. Here, we discuss advances in our understanding of how viruses counteract necroptosis, methods to quantify the pathway, its effects on viral pathogenesis, and its impact on cellular signaling.
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Affiliation(s)
- Crystal A Lawson
- School of Molecular Biosciences, Washington State University, Pullman, WA, USA
- Center for Reproductive Biology, Washington State University, Pullman, WA, USA
| | - Derek J Titus
- Providence Sacred Heart, Spokane Teaching Health Center, Spokane, WA, USA
| | - Heather S Koehler
- School of Molecular Biosciences, Washington State University, Pullman, WA, USA.
- Center for Reproductive Biology, Washington State University, Pullman, WA, USA.
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22
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Sethi A, Horne CR, Fitzgibbon C, Wilde K, Davies KA, Garnish SE, Jacobsen AV, Samson AL, Hildebrand JM, Wardak A, Czabotar PE, Petrie EJ, Gooley PR, Murphy JM. Membrane permeabilization is mediated by distinct epitopes in mouse and human orthologs of the necroptosis effector, MLKL. Cell Death Differ 2022; 29:1804-1815. [PMID: 35264780 PMCID: PMC9433430 DOI: 10.1038/s41418-022-00965-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 02/21/2022] [Accepted: 02/21/2022] [Indexed: 12/18/2022] Open
Abstract
Necroptosis is a lytic programmed cell death pathway with origins in innate immunity that is frequently dysregulated in inflammatory diseases. The terminal effector of the pathway, MLKL, is licensed to kill following phosphorylation of its pseudokinase domain by the upstream regulator, RIPK3 kinase. Phosphorylation provokes the unleashing of MLKL's N-terminal four-helix bundle (4HB or HeLo) domain, which binds and permeabilizes the plasma membrane to cause cell death. The precise mechanism by which the 4HB domain permeabilizes membranes, and how the mechanism differs between species, remains unclear. Here, we identify the membrane binding epitope of mouse MLKL using NMR spectroscopy. Using liposome permeabilization and cell death assays, we validate K69 in the α3 helix, W108 in the α4 helix, and R137/Q138 in the first brace helix as crucial residues for necroptotic signaling. This epitope differs from the phospholipid binding site reported for human MLKL, which comprises basic residues primarily located in the α1 and α2 helices. In further contrast to human and plant MLKL orthologs, in which the α3-α4 loop forms a helix, this loop is unstructured in mouse MLKL in solution. Together, these findings illustrate the versatility of the 4HB domain fold, whose lytic function can be mediated by distinct epitopes in different orthologs.
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Affiliation(s)
- Ashish Sethi
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Christopher R Horne
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Cheree Fitzgibbon
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Karyn Wilde
- National Deuteration Facility, Australian Nuclear Science and Technology Organization, Lucas Heights, NSW, 2234, Australia
| | - Katherine A Davies
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Sarah E Garnish
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Annette V Jacobsen
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - André L Samson
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Joanne M Hildebrand
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Ahmad Wardak
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
| | - Peter E Czabotar
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Emma J Petrie
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Paul R Gooley
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3010, Australia
| | - James M Murphy
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia.
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia.
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23
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Verburg SG, Lelievre RM, Westerveld MJ, Inkol JM, Sun YL, Workenhe ST. Viral-mediated activation and inhibition of programmed cell death. PLoS Pathog 2022; 18:e1010718. [PMID: 35951530 PMCID: PMC9371342 DOI: 10.1371/journal.ppat.1010718] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Viruses are ubiquitous intracellular genetic parasites that heavily rely on the infected cell to complete their replication life cycle. This dependency on the host machinery forces viruses to modulate a variety of cellular processes including cell survival and cell death. Viruses are known to activate and block almost all types of programmed cell death (PCD) known so far. Modulating PCD in infected hosts has a variety of direct and indirect effects on viral pathogenesis and antiviral immunity. The mechanisms leading to apoptosis following virus infection is widely studied, but several modalities of PCD, including necroptosis, pyroptosis, ferroptosis, and paraptosis, are relatively understudied. In this review, we cover the mechanisms by which viruses activate and inhibit PCDs and suggest perspectives on how these affect viral pathogenesis and immunity.
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Affiliation(s)
- Shayla Grace Verburg
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Canada
| | | | | | - Jordon Marcus Inkol
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Canada
| | - Yi Lin Sun
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Canada
| | - Samuel Tekeste Workenhe
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Canada
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24
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Zhang G, Wang J, Zhao Z, Xin T, Fan X, Shen Q, Raheem A, Lee CR, Jiang H, Ding J. Regulated necrosis, a proinflammatory cell death, potentially counteracts pathogenic infections. Cell Death Dis 2022; 13:637. [PMID: 35869043 PMCID: PMC9307826 DOI: 10.1038/s41419-022-05066-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 06/29/2022] [Accepted: 07/04/2022] [Indexed: 02/07/2023]
Abstract
Since the discovery of cell apoptosis, other gene-regulated cell deaths are gradually appreciated, including pyroptosis, ferroptosis, and necroptosis. Necroptosis is, so far, one of the best-characterized regulated necrosis. In response to diverse stimuli (death receptor or toll-like receptor stimulation, pathogenic infection, or other factors), necroptosis is initiated and precisely regulated by the receptor-interacting protein kinase 3 (RIPK3) with the involvement of its partners (RIPK1, TRIF, DAI, or others), ultimately leading to the activation of its downstream substrate, mixed lineage kinase domain-like (MLKL). Necroptosis plays a significant role in the host's defense against pathogenic infections. Although much has been recognized regarding modulatory mechanisms of necroptosis during pathogenic infection, the exact role of necroptosis at different stages of infectious diseases is still being unveiled, e.g., how and when pathogens utilize or evade necroptosis to facilitate their invasion and how hosts manipulate necroptosis to counteract these detrimental effects brought by pathogenic infections and further eliminate the encroaching pathogens. In this review, we summarize and discuss the recent progress in the role of necroptosis during a series of viral, bacterial, and parasitic infections with zoonotic potentials, aiming to provide references and directions for the prevention and control of infectious diseases of both human and animals.
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Affiliation(s)
- Guangzhi Zhang
- grid.464332.4Institute of Animal Sciences of Chinese Academy of Agricultural Sciences, Beijing, 100193 China
| | - Jinyong Wang
- grid.508381.70000 0004 0647 272XShenzhen Bay Laboratory, Institute of Infectious Diseases, Shenzhen, 518000 China ,grid.258164.c0000 0004 1790 3548Institute of Respiratory Diseases, Shenzhen People’s Hospital, The Second Clinical Medical College, Jinan University, Shenzhen, 518020 Guangdong China
| | - Zhanran Zhao
- grid.47840.3f0000 0001 2181 7878Department of Molecular and Cell Biology and Cancer Research Laboratory, University of California, Berkeley, CA 94720-3200 USA
| | - Ting Xin
- grid.464332.4Institute of Animal Sciences of Chinese Academy of Agricultural Sciences, Beijing, 100193 China
| | - Xuezheng Fan
- grid.464332.4Institute of Animal Sciences of Chinese Academy of Agricultural Sciences, Beijing, 100193 China
| | - Qingchun Shen
- grid.464332.4Institute of Animal Sciences of Chinese Academy of Agricultural Sciences, Beijing, 100193 China
| | - Abdul Raheem
- grid.464332.4Institute of Animal Sciences of Chinese Academy of Agricultural Sciences, Beijing, 100193 China ,grid.35155.370000 0004 1790 4137Present Address: Huazhong Agricultural University, Wuhan, China
| | - Chae Rhim Lee
- grid.47840.3f0000 0001 2181 7878Department of Molecular and Cell Biology and Cancer Research Laboratory, University of California, Berkeley, CA 94720-3200 USA ,grid.266093.80000 0001 0668 7243Present Address: University of California, Irvine, CA USA
| | - Hui Jiang
- grid.464332.4Institute of Animal Sciences of Chinese Academy of Agricultural Sciences, Beijing, 100193 China
| | - Jiabo Ding
- grid.464332.4Institute of Animal Sciences of Chinese Academy of Agricultural Sciences, Beijing, 100193 China
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25
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Nguyen LN, Kanneganti TD. PANoptosis in Viral Infection: The Missing Puzzle Piece in the Cell Death Field. J Mol Biol 2022; 434:167249. [PMID: 34537233 PMCID: PMC8444475 DOI: 10.1016/j.jmb.2021.167249] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 09/10/2021] [Indexed: 02/07/2023]
Abstract
In the past decade, emerging viral outbreaks like SARS-CoV-2, Zika and Ebola have presented major challenges to the global health system. Viruses are unique pathogens in that they fully rely on the host cell to complete their lifecycle and potentiate disease. Therefore, programmed cell death (PCD), a key component of the host innate immune response, is an effective strategy for the host cell to curb viral spread. The most well-established PCD pathways, pyroptosis, apoptosis and necroptosis, can be activated in response to viruses. Recently, extensive crosstalk between PCD pathways has been identified, and there is evidence that molecules from all three PCD pathways can be activated during virus infection. These findings have led to the emergence of the concept of PANoptosis, defined as an inflammatory PCD pathway regulated by the PANoptosome complex with key features of pyroptosis, apoptosis, and/or necroptosis that cannot be accounted for by any of these three PCD pathways alone. While PCD is important to eliminate infected cells, many viruses are equipped to hijack host PCD pathways to benefit their own propagation and subvert host defense, and PCD can also lead to the production of inflammatory cytokines and inflammation. Therefore, PANoptosis induced by viral infection contributes to either host defense or viral pathogenesis in context-specific ways. In this review, we will discuss the multi-faceted roles of PCD pathways in controlling viral infections.
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26
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Human cytomegalovirus protein RL1 degrades the antiviral factor SLFN11 via recruitment of the CRL4 E3 ubiquitin ligase complex. Proc Natl Acad Sci U S A 2022; 119:2108173119. [PMID: 35105802 PMCID: PMC8832970 DOI: 10.1073/pnas.2108173119] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/14/2021] [Indexed: 02/08/2023] Open
Abstract
Human cytomegalovirus (HCMV) is an important human pathogen and a paradigm of viral immune evasion, targeting intrinsic, innate, and adaptive immunity. We have employed two orthogonal multiplexed tandem mass tag-based proteomic screens to identify host proteins down-regulated by viral factors expressed during the latest phases of viral infection. This approach revealed that the HIV-1 restriction factor Schlafen-11 (SLFN11) was degraded by the poorly characterized, late-expressed HCMV protein RL1, via recruitment of the Cullin4-RING E3 Ubiquitin Ligase (CRL4) complex. SLFN11 potently restricted HCMV infection, inhibiting the formation and spread of viral plaques. Overall, we show that a restriction factor previously thought only to inhibit RNA viruses additionally restricts HCMV. We define the mechanism of viral antagonism and also describe an important resource for revealing additional molecules of importance in antiviral innate immunity and viral immune evasion.
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27
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Zhou YP, Mei MJ, Wang XZ, Huang SN, Chen L, Zhang M, Li XY, Qin HB, Dong X, Cheng S, Wen L, Yang B, An XF, He AD, Zhang B, Zeng WB, Li XJ, Lu Y, Li HC, Li H, Zou WG, Redwood AJ, Rayner S, Cheng H, McVoy MA, Tang Q, Britt WJ, Zhou X, Jiang X, Luo MH. A congenital CMV infection model for follow-up studies of neurodevelopmental disorders, neuroimaging abnormalities, and treatment. JCI Insight 2022; 7:152551. [PMID: 35014624 PMCID: PMC8765053 DOI: 10.1172/jci.insight.152551] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 11/23/2021] [Indexed: 12/28/2022] Open
Abstract
Congenital cytomegalovirus (cCMV) infection is the leading infectious cause of neurodevelopmental disorders. However, the neuropathogenesis remains largely elusive due to a lack of informative animal models. In this study, we developed a congenital murine CMV (cMCMV) infection mouse model with high survival rate and long survival period that allowed long-term follow-up study of neurodevelopmental disorders. This model involves in utero intracranial injection and mimics many reported clinical manifestations of cCMV infection in infants, including growth restriction, hearing loss, and impaired cognitive and learning-memory abilities. We observed that abnormalities in MRI/CT neuroimaging were consistent with brain hemorrhage and loss of brain parenchyma, which was confirmed by pathological analysis. Neuropathological findings included ventriculomegaly and cortical atrophy associated with impaired proliferation and migration of neural progenitor cells in the developing brain at both embryonic and postnatal stages. Robust inflammatory responses during infection were shown by elevated inflammatory cytokine levels, leukocyte infiltration, and activation of microglia and astrocytes in the brain. Pathological analyses and CT neuroimaging revealed brain calcifications induced by cMCMV infection and cell death via pyroptosis. Furthermore, antiviral treatment with ganciclovir significantly improved neurological functions and mitigated brain damage as shown by CT neuroimaging. These results demonstrate that this model is suitable for investigation of mechanisms of infection-induced brain damage and long-term studies of neurodevelopmental disorders, including the development of interventions to limit CNS damage associated with cCMV infection.
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Affiliation(s)
- Yue-Peng Zhou
- State Key Laboratory of Virology, CAS Center for Excellence in Brain Science and Intelligence Technology, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Meng-Jie Mei
- State Key Laboratory of Virology, CAS Center for Excellence in Brain Science and Intelligence Technology, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Xian-Zhang Wang
- State Key Laboratory of Virology, CAS Center for Excellence in Brain Science and Intelligence Technology, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Sheng-Nan Huang
- State Key Laboratory of Virology, CAS Center for Excellence in Brain Science and Intelligence Technology, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Lin Chen
- Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Ming Zhang
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, China
| | - Xin-Yan Li
- The Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan, China
| | - Hai-Bin Qin
- State Key Laboratory of Virology, CAS Center for Excellence in Brain Science and Intelligence Technology, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Xiao Dong
- State Key Laboratory of Virology, CAS Center for Excellence in Brain Science and Intelligence Technology, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Shuang Cheng
- State Key Laboratory of Virology, CAS Center for Excellence in Brain Science and Intelligence Technology, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Le Wen
- State Key Laboratory of Virology, CAS Center for Excellence in Brain Science and Intelligence Technology, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,The Joint Center of Translational Precision Medicine, Guangzhou Institute of Pediatrics, Guangzhou Women and Children Medical Center, Guangzhou, China
| | - Bo Yang
- State Key Laboratory of Virology, CAS Center for Excellence in Brain Science and Intelligence Technology, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,The Joint Center of Translational Precision Medicine, Guangzhou Institute of Pediatrics, Guangzhou Women and Children Medical Center, Guangzhou, China
| | - Xue-Fang An
- State Key Laboratory of Virology, CAS Center for Excellence in Brain Science and Intelligence Technology, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Ao-Di He
- The Joint Center of Translational Precision Medicine, Guangzhou Institute of Pediatrics, Guangzhou Women and Children Medical Center, Guangzhou, China
| | - Bing Zhang
- The Joint Center of Translational Precision Medicine, Guangzhou Institute of Pediatrics, Guangzhou Women and Children Medical Center, Guangzhou, China
| | - Wen-Bo Zeng
- State Key Laboratory of Virology, CAS Center for Excellence in Brain Science and Intelligence Technology, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Xiao-Jun Li
- State Key Laboratory of Virology, CAS Center for Excellence in Brain Science and Intelligence Technology, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Youming Lu
- The Joint Center of Translational Precision Medicine, Guangzhou Institute of Pediatrics, Guangzhou Women and Children Medical Center, Guangzhou, China
| | - Hong-Chuang Li
- University of Chinese Academy of Sciences, Beijing, China.,Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, China
| | - Haidong Li
- University of Chinese Academy of Sciences, Beijing, China.,Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, China
| | - Wei-Guo Zou
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Sciences, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Alec J. Redwood
- The Institute for Respiratory Health, University of Western Australia, Crawley, Western Australia, Australia
| | - Simon Rayner
- Department of Medical Genetics, Oslo University Hospital and University of Oslo, Oslo, Norway.,Hybrid Technology Hub — Centre of Excellence, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Han Cheng
- Shanghai Public Health Clinical Center, Fudan University, Shanghai, China
| | - Michael A. McVoy
- Department of Pediatrics, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Qiyi Tang
- Department of Microbiology, Howard University College of Medicine, Washington, DC, USA
| | - William J. Britt
- Department of Pediatrics, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Xin Zhou
- University of Chinese Academy of Sciences, Beijing, China.,Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, China
| | - Xuan Jiang
- State Key Laboratory of Virology, CAS Center for Excellence in Brain Science and Intelligence Technology, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,The Joint Center of Translational Precision Medicine, Guangzhou Institute of Pediatrics, Guangzhou Women and Children Medical Center, Guangzhou, China
| | - Min-Hua Luo
- State Key Laboratory of Virology, CAS Center for Excellence in Brain Science and Intelligence Technology, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China.,The Joint Center of Translational Precision Medicine, Guangzhou Institute of Pediatrics, Guangzhou Women and Children Medical Center, Guangzhou, China.,Shanghai Public Health Clinical Center, Fudan University, Shanghai, China
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28
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Viral manipulation of host cell necroptosis and pyroptosis. Trends Microbiol 2021; 30:593-605. [PMID: 34933805 DOI: 10.1016/j.tim.2021.11.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 11/16/2021] [Accepted: 11/22/2021] [Indexed: 12/27/2022]
Abstract
Cell death forms an essential component of the antiviral immune response. Viral infection elicits different forms of host cell death, including the lytic and inflammatory cell death modes necroptosis or pyroptosis. The induction of both types of cell death not only eliminates virus-infected cells but also contributes to the development of innate and adaptive immunity through the release of inflammatory mediators. The importance of necroptosis and pyroptosis in host defence is evident from the numerous viral evasion mechanisms that suppress these cell death pathways. Here, we review the emerging principles by which viruses antagonise host cell necroptosis and pyroptosis to promote their spread and block host immunity.
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29
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Meng Y, Davies KA, Fitzgibbon C, Young SN, Garnish SE, Horne CR, Luo C, Garnier JM, Liang LY, Cowan AD, Samson AL, Lessene G, Sandow JJ, Czabotar PE, Murphy JM. Human RIPK3 maintains MLKL in an inactive conformation prior to cell death by necroptosis. Nat Commun 2021; 12:6783. [PMID: 34811356 PMCID: PMC8608796 DOI: 10.1038/s41467-021-27032-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 10/29/2021] [Indexed: 12/11/2022] Open
Abstract
The ancestral origins of the lytic cell death mode, necroptosis, lie in host defense. However, the dysregulation of necroptosis in inflammatory diseases has led to widespread interest in targeting the pathway therapeutically. This mode of cell death is executed by the terminal effector, the MLKL pseudokinase, which is licensed to kill following phosphorylation by its upstream regulator, RIPK3 kinase. The precise molecular details underlying MLKL activation are still emerging and, intriguingly, appear to mechanistically-diverge between species. Here, we report the structure of the human RIPK3 kinase domain alone and in complex with the MLKL pseudokinase. These structures reveal how human RIPK3 structurally differs from its mouse counterpart, and how human RIPK3 maintains MLKL in an inactive conformation prior to induction of necroptosis. Residues within the RIPK3:MLKL C-lobe interface are crucial to complex assembly and necroptotic signaling in human cells, thereby rationalizing the strict species specificity governing RIPK3 activation of MLKL.
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Affiliation(s)
- Yanxiang Meng
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Katherine A Davies
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Cheree Fitzgibbon
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Samuel N Young
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
| | - Sarah E Garnish
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Christopher R Horne
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Cindy Luo
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
| | - Jean-Marc Garnier
- SYNthesis med chem, 30 Flemington Rd, Parkville, VIC, 3052, Australia
| | - Lung-Yu Liang
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Angus D Cowan
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Andre L Samson
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Guillaume Lessene
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Jarrod J Sandow
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Peter E Czabotar
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia.
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia.
| | - James M Murphy
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia.
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia.
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Muscolino E, Castiglioni C, Brixel R, Frascaroli G, Brune W. Species-Specific Inhibition of Necroptosis by HCMV UL36. Viruses 2021; 13:v13112134. [PMID: 34834942 PMCID: PMC8621378 DOI: 10.3390/v13112134] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 10/18/2021] [Accepted: 10/19/2021] [Indexed: 12/31/2022] Open
Abstract
Viral infection activates cellular antiviral defenses including programmed cell death (PCD). Many viruses, particularly those of the Herpesviridae family, encode cell death inhibitors that antagonize different forms of PCD. While some viral inhibitors are broadly active in cells of different species, others have species-specific functions, probably reflecting the co-evolution of the herpesviruses with their respective hosts. Human cytomegalovirus (HCMV) protein UL36 is a dual cell death pathway inhibitor. It blocks death receptor-dependent apoptosis by inhibiting caspase-8 activation, and necroptosis by binding to the mixed lineage kinase domain-like (MLKL) protein and inducing its degradation. While UL36 has been shown to inhibit apoptosis in human and murine cells, the specificity of its necroptosis-inhibiting function has not been investigated. Here we show that UL36 interacts with both human and murine MLKL, but has a higher affinity for human MLKL. When expressed by a recombinant mouse cytomegalovirus (MCMV), UL36 caused a modest reduction of murine MLKL levels but did not inhibit necroptosis in murine cells. These data suggest that UL36 inhibits necroptosis, but not apoptosis, in a species-specific manner, similar to ICP6 of herpes simplex virus type 1 and MC159 of molluscum contagiosum virus. Species-specific necroptosis inhibition might contribute to the narrow host range of these viruses.
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Affiliation(s)
- Elena Muscolino
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany; (E.M.); (C.C.); (R.B.); (G.F.)
- Molecular Virology Group, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Claudia Castiglioni
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany; (E.M.); (C.C.); (R.B.); (G.F.)
| | - Renke Brixel
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany; (E.M.); (C.C.); (R.B.); (G.F.)
| | - Giada Frascaroli
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany; (E.M.); (C.C.); (R.B.); (G.F.)
| | - Wolfram Brune
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany; (E.M.); (C.C.); (R.B.); (G.F.)
- Correspondence: ; Tel.: +49-40-48051351
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31
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Palmer S, Chappidi S, Pinkham C, Hancks DC. Evolutionary profile for (host and viral) MLKL indicates its activities as a battlefront for extensive counteradaptation. Mol Biol Evol 2021; 38:5405-5422. [PMID: 34436583 PMCID: PMC8662602 DOI: 10.1093/molbev/msab256] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Pathogen infection triggers host innate defenses which may result in the activation of regulated cell death (RCD) pathways such as apoptosis. Given a vital role in immunity, apoptotic effectors are often counteracted by pathogen-encoded antagonists. Mounting evidence indicates that programmed necrosis, which is mediated by the RIPK3/MLKL axis and termed necroptosis, evolved as a countermeasure to pathogen-mediated inhibition of apoptosis. Yet, it is unclear whether components of this emerging RCD pathway display signatures associated with pathogen conflict that are rare in combination but common to key host defense factors, namely, rapid evolution, viral homolog (virolog), and cytokine induction. We leveraged evolutionary sequence analysis that examines rates of amino acid replacement, which revealed: 1) strong and recurrent signatures of positive selection for primate and bat RIPK3 and MLKL, and 2) elevated rates of amino acid substitution on multiple RIPK3/MLKL surfaces suggestive of past antagonism with multiple, distinct pathogen-encoded inhibitors. Furthermore, our phylogenomics analysis across poxvirus genomes illuminated volatile patterns of evolution for a recently described MLKL viral homolog. Specifically, poxviral MLKLs have undergone numerous gene replacements mediated by duplication and deletion events. In addition, MLKL protein expression is stimulated by interferons in human and mouse cells. Thus, MLKL displays all three hallmarks of pivotal immune factors of which only a handful of factors like OAS1 exhibit. These data support the hypothesis that over evolutionary time MLKL functions—which may include execution of necroptosis—have served as a major determinant of infection outcomes despite gene loss in some host genomes.
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Affiliation(s)
- Suzette Palmer
- Department of Immunology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Sruthi Chappidi
- Department of Immunology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Chelsea Pinkham
- Department of Immunology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Dustin C Hancks
- Department of Immunology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
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32
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Abstract
The abundance, localization, modifications, and protein-protein interactions of many host cell and virus proteins can change dynamically throughout the course of any viral infection. Studying these changes is critical for a comprehensive understanding of how viruses replicate and cause disease, as well as for the development of antiviral therapeutics and vaccines. Previously, we developed a mass spectrometry-based technique called quantitative temporal viromics (QTV), which employs isobaric tandem mass tags (TMTs) to allow precise comparative quantification of host and virus proteomes through a whole time course of infection. In this review, we discuss the utility and applications of QTV, exemplified by numerous studies that have since used proteomics with a variety of quantitative techniques to study virus infection through time. Expected final online publication date for the Annual Review of Virology, Volume 8 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
| | - Michael P Weekes
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom;
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33
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Bertheloot D, Latz E, Franklin BS. Necroptosis, pyroptosis and apoptosis: an intricate game of cell death. Cell Mol Immunol 2021; 18:1106-1121. [PMID: 33785842 PMCID: PMC8008022 DOI: 10.1038/s41423-020-00630-3] [Citation(s) in RCA: 821] [Impact Index Per Article: 273.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 12/15/2020] [Indexed: 02/01/2023] Open
Abstract
Cell death is a fundamental physiological process in all living organisms. Its roles extend from embryonic development, organ maintenance, and aging to the coordination of immune responses and autoimmunity. In recent years, our understanding of the mechanisms orchestrating cellular death and its consequences on immunity and homeostasis has increased substantially. Different modalities of what has become known as 'programmed cell death' have been described, and some key players in these processes have been identified. We have learned more about the intricacies that fine tune the activity of common players and ultimately shape the different types of cell death. These studies have highlighted the complex mechanisms tipping the balance between different cell fates. Here, we summarize the latest discoveries in the three most well understood modalities of cell death, namely, apoptosis, necroptosis, and pyroptosis, highlighting common and unique pathways and their effect on the surrounding cells and the organism as a whole.
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Affiliation(s)
- Damien Bertheloot
- Institute of Innate Immunity, University Hospitals Bonn, University of Bonn, Bonn, NRW, Germany.
| | - Eicke Latz
- Institute of Innate Immunity, University Hospitals Bonn, University of Bonn, Bonn, NRW, Germany
- Department of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA, USA
- German Center for Neurodegenerative Diseases, Bonn, NRW, Germany
| | - Bernardo S Franklin
- Institute of Innate Immunity, University Hospitals Bonn, University of Bonn, Bonn, NRW, Germany.
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34
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Yu Z, Wang Y, Liu L, Zhang X, Jiang S, Wang B. Apoptosis Disorder, a Key Pathogenesis of HCMV-Related Diseases. Int J Mol Sci 2021; 22:ijms22084106. [PMID: 33921122 PMCID: PMC8071541 DOI: 10.3390/ijms22084106] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/09/2021] [Accepted: 04/13/2021] [Indexed: 02/07/2023] Open
Abstract
Human cytomegalovirus (HCMV) belongs to the β-herpesvirus family, which is transmitted in almost every part of the world and is carried by more than 90% of the general population. Increasing evidence indicates that HCMV infection triggers numerous diseases by disrupting the normal physiological activity of host cells, particularly apoptosis. Apoptosis disorder plays a key role in the initiation and development of multiple diseases. However, the relationship and molecular mechanism of HCMV-related diseases and apoptosis have not yet been systematically summarized. This review aims to summarize the role of apoptosis in HCMV-related diseases and provide an insight into the molecular mechanism of apoptosis induced by HCMV infection. We summarize the literature on HCMV-related diseases and suggest novel strategies for HCMV treatment by regulating apoptosis.
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Affiliation(s)
- Zhongjie Yu
- Department of Special Medicine, School of Basic Medicine, Qingdao Medical College, Qingdao University, Qingdao 266000, China;
| | - Yashuo Wang
- College of Life Sciences, Qingdao University, Qingdao 266000, China;
| | - Lili Liu
- Department of Basic Medicine, School of Basic Medicine, Qingdao Medical College, Qingdao University, Qingdao 266000, China;
| | - Xianjuan Zhang
- Department of Pathogenic Biology, School of Basic Medicine, Qingdao Medical College, Qingdao University, Qingdao 266000, China; (X.Z.); (S.J.)
| | - Shasha Jiang
- Department of Pathogenic Biology, School of Basic Medicine, Qingdao Medical College, Qingdao University, Qingdao 266000, China; (X.Z.); (S.J.)
| | - Bin Wang
- Department of Special Medicine, School of Basic Medicine, Qingdao Medical College, Qingdao University, Qingdao 266000, China;
- Correspondence: ; Tel.: +86-136-8532-6203
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35
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Meng Y, Sandow JJ, Czabotar PE, Murphy JM. The regulation of necroptosis by post-translational modifications. Cell Death Differ 2021; 28:861-883. [PMID: 33462412 PMCID: PMC7937688 DOI: 10.1038/s41418-020-00722-7] [Citation(s) in RCA: 70] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 12/14/2020] [Accepted: 12/18/2020] [Indexed: 01/30/2023] Open
Abstract
Necroptosis is a caspase-independent, lytic form of programmed cell death whose errant activation has been widely implicated in many pathologies. The pathway relies on the assembly of the apical protein kinases, RIPK1 and RIPK3, into a high molecular weight cytoplasmic complex, termed the necrosome, downstream of death receptor or pathogen detector ligation. The necrosome serves as a platform for RIPK3-mediated phosphorylation of the terminal effector, the MLKL pseudokinase, which induces its oligomerization, translocation to, and perturbation of, the plasma membrane to cause cell death. Over the past 10 years, knowledge of the post-translational modifications that govern RIPK1, RIPK3 and MLKL conformation, activity, interactions, stability and localization has rapidly expanded. Here, we review current knowledge of the functions of phosphorylation, ubiquitylation, GlcNAcylation, proteolytic cleavage, and disulfide bonding in regulating necroptotic signaling. Post-translational modifications serve a broad array of functions in modulating RIPK1 engagement in, or exclusion from, cell death signaling, whereas the bulk of identified RIPK3 and MLKL modifications promote their necroptotic functions. An enhanced understanding of the modifying enzymes that tune RIPK1, RIPK3, and MLKL necroptotic functions will prove valuable in efforts to therapeutically modulate necroptosis.
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Affiliation(s)
- Yanxiang Meng
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Jarrod J Sandow
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Peter E Czabotar
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - James M Murphy
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia.
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia.
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36
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HIV-1 Latency and Viral Reservoirs: Existing Reversal Approaches and Potential Technologies, Targets, and Pathways Involved in HIV Latency Studies. Cells 2021; 10:cells10020475. [PMID: 33672138 PMCID: PMC7926981 DOI: 10.3390/cells10020475] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 02/14/2021] [Accepted: 02/20/2021] [Indexed: 02/07/2023] Open
Abstract
Eradication of latent human immunodeficiency virus (HIV) infection is a global health challenge. Reactivation of HIV latency and killing of virus-infected cells, the so-called "kick and kill" or "shock and kill" approaches, are a popular strategy for HIV cure. While antiretroviral therapy (ART) halts HIV replication by targeting multiple steps in the HIV life cycle, including viral entry, integration, replication, and production, it cannot get rid of the occult provirus incorporated into the host-cell genome. These latent proviruses are replication-competent and can rebound in cases of ART interruption or cessation. In general, a very small population of cells harbor provirus, serve as reservoirs in ART-controlled HIV subjects, and are capable of expressing little to no HIV RNA or proteins. Beyond the canonical resting memory CD4+ T cells, HIV reservoirs also exist within tissue macrophages, myeloid cells, brain microglial cells, gut epithelial cells, and hematopoietic stem cells (HSCs). Despite a lack of active viral production, latently HIV-infected subjects continue to exhibit aberrant cellular signaling and metabolic dysfunction, leading to minor to major cellular and systemic complications or comorbidities. These include genomic DNA damage; telomere attrition; mitochondrial dysfunction; premature aging; and lymphocytic, cardiac, renal, hepatic, or pulmonary dysfunctions. Therefore, the arcane machineries involved in HIV latency and its reversal warrant further studies to identify the cryptic mechanisms of HIV reservoir formation and clearance. In this review, we discuss several molecules and signaling pathways, some of which have dual roles in maintaining or reversing HIV latency and reservoirs, and describe some evolving strategies and possible approaches to eliminate viral reservoirs and, ultimately, cure/eradicate HIV infection.
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37
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Samson AL, Fitzgibbon C, Patel KM, Hildebrand JM, Whitehead LW, Rimes JS, Jacobsen AV, Horne CR, Gavin XJ, Young SN, Rogers KL, Hawkins ED, Murphy JM. A toolbox for imaging RIPK1, RIPK3, and MLKL in mouse and human cells. Cell Death Differ 2021; 28:2126-2144. [PMID: 33589776 DOI: 10.1038/s41418-021-00742-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 01/20/2021] [Accepted: 01/25/2021] [Indexed: 12/18/2022] Open
Abstract
Necroptosis is a lytic, inflammatory cell death pathway that is dysregulated in many human pathologies. The pathway is executed by a core machinery comprising the RIPK1 and RIPK3 kinases, which assemble into necrosomes in the cytoplasm, and the terminal effector pseudokinase, MLKL. RIPK3-mediated phosphorylation of MLKL induces oligomerization and translocation to the plasma membrane where MLKL accumulates as hotspots and perturbs the lipid bilayer to cause death. The precise choreography of events in the pathway, where they occur within cells, and pathway differences between species, are of immense interest. However, they have been poorly characterized due to a dearth of validated antibodies for microscopy studies. Here, we describe a toolbox of antibodies for immunofluorescent detection of the core necroptosis effectors, RIPK1, RIPK3, and MLKL, and their phosphorylated forms, in human and mouse cells. By comparing reactivity with endogenous proteins in wild-type cells and knockout controls in basal and necroptosis-inducing conditions, we characterise the specificity of frequently-used commercial and recently-developed antibodies for detection of necroptosis signaling events. Importantly, our findings demonstrate that not all frequently-used antibodies are suitable for monitoring necroptosis by immunofluorescence microscopy, and methanol- is preferable to paraformaldehyde-fixation for robust detection of specific RIPK1, RIPK3, and MLKL signals.
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Affiliation(s)
- André L Samson
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia. .,Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia.
| | - Cheree Fitzgibbon
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
| | - Komal M Patel
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
| | - Joanne M Hildebrand
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Lachlan W Whitehead
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Joel S Rimes
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Annette V Jacobsen
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Christopher R Horne
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Xavier J Gavin
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Samuel N Young
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
| | - Kelly L Rogers
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Edwin D Hawkins
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - James M Murphy
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia. .,Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia.
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38
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Samson AL, Garnish SE, Hildebrand JM, Murphy JM. Location, location, location: A compartmentalized view of TNF-induced necroptotic signaling. Sci Signal 2021; 14:14/668/eabc6178. [PMID: 33531383 DOI: 10.1126/scisignal.abc6178] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Necroptosis is a lytic, proinflammatory cell death pathway, which has been implicated in host defense and, when dysregulated, the pathology of many human diseases. The central mediators of this pathway are the receptor-interacting serine/threonine protein kinases RIPK1 and RIPK3 and the terminal executioner, the pseudokinase mixed lineage kinase domain-like (MLKL). Here, we review the chronology of signaling along the RIPK1-RIPK3-MLKL axis and highlight how the subcellular compartmentalization of signaling events controls the initiation and execution of necroptosis. We propose that a network of modulators surrounds the necroptotic signaling core and that this network, rather than acting universally, tunes necroptosis in a context-, cell type-, and species-dependent manner. Such a high degree of mechanistic flexibility is likely an important property that helps necroptosis operate as a robust, emergency form of cell death.
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Affiliation(s)
- André L Samson
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia. .,Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Sarah E Garnish
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Joanne M Hildebrand
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - James M Murphy
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia. .,Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
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39
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Modulation of Apoptosis and Cell Death Pathways by Varicella-Zoster Virus. Curr Top Microbiol Immunol 2021; 438:59-73. [DOI: 10.1007/82_2021_249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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40
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TNF Signaling Dictates Myeloid and Non-Myeloid Cell Crosstalk to Execute MCMV-Induced Extrinsic Apoptosis. Viruses 2020; 12:v12111221. [PMID: 33126536 PMCID: PMC7693317 DOI: 10.3390/v12111221] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/21/2020] [Accepted: 10/24/2020] [Indexed: 12/13/2022] Open
Abstract
Cytomegaloviruses all encode the viral inhibitor of caspase-8-induced apoptosis (vICA). After binding to this initiator caspase, vICA blocks caspase-8 proteolytic activity and ability to activate caspase-3 and/or caspase-7. In this manner, vICA has long been known to prevent apoptosis triggered via tumor necrosis factor (TNF) family death receptor-dependent extrinsic signaling. Here, we employ fully wild-type murine cytomegalovirus (MCMV) and vICA-deficient MCMV (∆M36) to investigate the contribution of TNF signaling to apoptosis during infection of different cell types. ∆M36 shows the expected ability to kill mouse splenic hematopoietic cells, bone marrow-derived macrophages (BMDM), and dendritic cells (BMDC). Antibody blockade or genetic elimination of TNF protects myeloid cells from death, and caspase-8 activation accompanies cell death. Interferons, necroptosis, and pyroptotic gasdermin D (GSDMD) do not contribute to myeloid cell death. Human and murine fibroblasts or murine endothelial cells (SVEC4-10) normally insensitive to TNF become sensitized to ∆M36-induced apoptosis when treated with TNF or TNF-containing BMDM-conditioned medium. We demonstrate that myeloid cells are the natural source of TNF that triggers apoptosis in either myeloid (autocrine) or non-myeloid cells (paracrine) during ∆M36 infection of mice. Caspase-8 suppression by vICA emerges as key to subverting innate immune elimination of a wide variety of infected cell types.
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41
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Human Cytomegalovirus-Induced Autophagy Prevents Necroptosis of Infected Monocytes. J Virol 2020; 94:JVI.01022-20. [PMID: 32878887 DOI: 10.1128/jvi.01022-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 08/21/2020] [Indexed: 12/20/2022] Open
Abstract
Key to the viral dissemination strategy of human cytomegalovirus (HCMV) is the induction of monocyte survival, where monocytes are normally short-lived cells. Autophagy is a cellular process that preserves cellular homeostasis and promotes cellular survival during times of stress. We found that HCMV rapidly induced autophagy within infected monocytes. The early induction of autophagy during HCMV infection was distinctly required for the survival of HCMV-infected monocytes, as repression of autophagosome formation led to cellular death of infected cells but had no effect on the viability of uninfected monocytes. The inhibition of caspases was insufficient to rescue cell viability of autophagy-repressed infected monocytes, suggesting that autophagy was not protecting cells from apoptosis. Accordingly, we found that HCMV blocked the activation of caspase 8, which was maintained in the presence of autophagy inhibitors. Necroptosis is an alternative form of cell death triggered when apoptosis is impeded and is dependent on RIPK3 phosphorylation of MLKL. Although we found that HCMV activated RIP3K upon infection, MLKL was not activated. However, inhibition of autophagy removed the block in RIPK3 phosphorylation of MLKL, suggesting that autophagy was protecting infected monocytes from undergoing necroptosis. Indeed, survival of autophagy-inhibited HCMV-infected monocytes was rescued when MLKL and RIPK3 were suppressed. Taken together, these data indicate that HCMV induces autophagy to prevent necroptotic cell death in order to ensure the survival of infected monocytes and thus facilitate viral dissemination within the host.IMPORTANCE Human cytomegalovirus (HCMV) infection is endemic throughout the world, with a seroprevalence of 40 to 100% depending on geographic location. HCMV infection is generally asymptomatic, but can cause severe inflammatory organ diseases in immunocompromised individuals. The broad array of organ diseases caused by HCMV is directly linked to the systematic spread of the virus mediated by monocytes. Monocytes are naturally programmed to undergo apoptosis, which is rapidly blocked by HCMV to ensure the survival and dissemination of infected monocytes to different organ sites. In this work, we demonstrate infected monocytes also initiate necroptosis as a "trap door" death pathway in response to HCMV subversion of apoptosis. HCMV then activates cellular autophagy as a countermeasure to prevent the execution of necroptosis, thereby promoting the continued survival of infected monocytes. Elucidating the mechanisms by which HCMV stimulates monocyte survival is an important step to the development of novel anti-HCMV drugs that prevent the spread of infected monocytes.
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42
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Abstract
Human cytomegalovirus (HCMV) is an important human pathogen and a paradigm of intrinsic, innate, and adaptive viral immune evasion. Here, we employed multiplexed tandem mass tag-based proteomics to characterize host proteins targeted for degradation late during HCMV infection. This approach revealed that mixed lineage kinase domain-like protein (MLKL), a key terminal mediator of cellular necroptosis, was rapidly and persistently degraded by the minimally passaged HCMV strain Merlin but not the extensively passaged strain AD169. The strain Merlin viral inhibitor of apoptosis pUL36 was necessary and sufficient both to degrade MLKL and to inhibit necroptosis. Furthermore, mutation of pUL36 Cys131 abrogated MLKL degradation and restored necroptosis. As the same residue is also required for pUL36-mediated inhibition of apoptosis by preventing proteolytic activation of procaspase-8, we define pUL36 as a multifunctional inhibitor of both apoptotic and necroptotic cell death.
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