51
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Cheng YL, Lin YS, Chen CL, Tsai TT, Tsai CC, Wu YW, Ou YD, Chu YY, Wang JM, Yu CY, Lin CF. Activation of Nrf2 by the dengue virus causes an increase in CLEC5A, which enhances TNF-α production by mononuclear phagocytes. Sci Rep 2016; 6:32000. [PMID: 27561946 PMCID: PMC4999957 DOI: 10.1038/srep32000] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 07/27/2016] [Indexed: 12/11/2022] Open
Abstract
Infection by the dengue virus (DENV) threatens global public health due to its high prevalence and the lack of effective treatments. Host factors may contribute to the pathogenesis of DENV; herein, we investigated the role of nuclear factor (erythroid-derived 2)-like 2 (Nrf2), which is activated by DENV in mononuclear phagocytes. DENV infection selectively activates Nrf2 following nuclear translocation. Following endoplasmic reticular (ER) stress, protein kinase R-like ER kinase (PERK) facilitated Nrf2-mediated transcriptional activation of C-type lectin domain family 5, member A (CLEC5A) to increase CLEC5A expression. Signaling downstream of the Nrf2-CLEC5A interaction enhances Toll-like receptor 3 (TLR3)-independent tumor necrosis factor (TNF)-α production following DENV infection. Forced expression of the NS2B3 viral protein induces Nrf2 nuclear translocation/activation and CLEC5A expression which increases DENV-induced TNF-α production. Animal studies confirmed Nrf2-induced CLEC5A and TNF-α in brains of DENV-infected mice. These results demonstrate that DENV infection causes Nrf2-regulated TNF-α production by increasing levels of CLEC5A.
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Affiliation(s)
- Yi-Lin Cheng
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan.,Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan 701, Taiwan
| | - Yee-Shin Lin
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan.,Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan 701, Taiwan.,Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan
| | - Chia-Ling Chen
- Translational Research Center, Taipei Medical University, Taipei 110, Taiwan
| | - Tsung-Ting Tsai
- Department of Microbiology and Immunology, College of Medicine, Taipei Medical University, Taipei 110, Taiwan
| | - Cheng-Chieh Tsai
- Department of Nursing, Chung Hwa University of Medical Technology, Tainan 717, Taiwan
| | - Yan-Wei Wu
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan.,Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan 701, Taiwan
| | - Yi-Dan Ou
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan
| | - Yu-Yi Chu
- Institute of Bioinformatics and Biosignal Transduction, National Cheng Kung University, Tainan 701, Taiwan
| | - Ju-Ming Wang
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan.,Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan 701, Taiwan.,Institute of Bioinformatics and Biosignal Transduction, National Cheng Kung University, Tainan 701, Taiwan
| | - Chia-Yi Yu
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan
| | - Chiou-Feng Lin
- Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan 701, Taiwan.,Department of Microbiology and Immunology, College of Medicine, Taipei Medical University, Taipei 110, Taiwan.,Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei 110, Taiwan
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52
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Cyclopentenone-containing oxidized phospholipids and their isoprostanes as pro-resolving mediators of inflammation. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1862:382-392. [PMID: 27422370 DOI: 10.1016/j.bbalip.2016.07.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 07/08/2016] [Accepted: 07/08/2016] [Indexed: 12/31/2022]
Abstract
Inflammation represents a powerful innate immune response that defends tissue homeostasis. However, the appropriate termination of inflammatory processes is essential to prevent the development of chronic inflammatory disorders. The resolution of inflammation is actively induced by specialized pro-resolving lipid mediators, which include eicosanoids, resolvins, protectins and maresins. The responsible pro-resolution pathways have emerged as promising targets for anti-inflammatory therapies since they mitigate excessive inflammation without compromising the anti-microbial defenses of the host. We have recently shown that the lipid peroxidation of membrane phospholipids, which is associated with inflammatory conditions, generates oxidized phospholipid (OxPL) species with potent pro-resolving activities. These pro-resolving OxPLs contain a cyclopentenone as their common determinant, and are structurally and functionally related to endogenous pro-resolving prostaglandins. Here, we review the regulation of inflammatory responses by OxPLs with particular focus on the bioactivities and structural characteristics of cyclopentenone-OxPLs, and discuss the impact of the responsible signaling pathways on inflammatory diseases. This article is part of a Special Issue entitled: Lipid modification and lipid peroxidation products in innate immunity and inflammation edited by Christoph J. Binder.
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53
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Schmidt KM, Mühlberger E. Marburg Virus Reverse Genetics Systems. Viruses 2016; 8:E178. [PMID: 27338448 PMCID: PMC4926198 DOI: 10.3390/v8060178] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 06/14/2016] [Accepted: 06/16/2016] [Indexed: 12/16/2022] Open
Abstract
The highly pathogenic Marburg virus (MARV) is a member of the Filoviridae family and belongs to the group of nonsegmented negative-strand RNA viruses. Reverse genetics systems established for MARV have been used to study various aspects of the viral replication cycle, analyze host responses, image viral infection, and screen for antivirals. This article provides an overview of the currently established MARV reverse genetic systems based on minigenomes, infectious virus-like particles and full-length clones, and the research that has been conducted using these systems.
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Affiliation(s)
- Kristina Maria Schmidt
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Novel and Emerging Infectious Diseases, Greifswald-Insel Riems 17493, Germany.
| | - Elke Mühlberger
- Department of Microbiology, School of Medicine, Boston University, 620 Albany Street, Boston, MA 02118, USA.
- National Emerging Infectious Diseases Laboratories (NEIDL), Boston University, 620 Albany Street, Boston, MA 02118, USA.
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54
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Effects of Filovirus Interferon Antagonists on Responses of Human Monocyte-Derived Dendritic Cells to RNA Virus Infection. J Virol 2016; 90:5108-5118. [PMID: 26962215 DOI: 10.1128/jvi.00191-16] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 03/06/2016] [Indexed: 12/14/2022] Open
Abstract
UNLABELLED Dendritic cells (DCs) are major targets of filovirus infection in vivo Previous studies have shown that the filoviruses Ebola virus (EBOV) and Marburg virus (MARV) suppress DC maturation in vitro Both viruses also encode innate immune evasion functions. The EBOV VP35 (eVP35) and the MARV VP35 (mVP35) proteins each can block RIG-I-like receptor signaling and alpha/beta interferon (IFN-α/β) production. The EBOV VP24 (eVP24) and MARV VP40 (mVP40) proteins each inhibit the production of IFN-stimulated genes (ISGs) by blocking Jak-STAT signaling; however, this occurs by different mechanisms, with eVP24 blocking nuclear import of tyrosine-phosphorylated STAT1 and mVP40 blocking Jak1 function. MARV VP24 (mVP24) has been demonstrated to modulate host cell antioxidant responses. Previous studies demonstrated that eVP35 is sufficient to strongly impair primary human monocyte-derived DC (MDDC) responses upon stimulation induced through the RIG-I-like receptor pathways. We demonstrate that mVP35, like eVP35, suppresses not only IFN-α/β production but also proinflammatory responses after stimulation of MDDCs with RIG-I activators. In contrast, eVP24 and mVP40, despite suppressing ISG production upon RIG-I activation, failed to block upregulation of maturation markers or T cell activation. mVP24, although able to stimulate expression of antioxidant response genes, had no measurable impact of DC function. These data are consistent with a model where filoviral VP35 proteins are the major suppressors of DC maturation during filovirus infection, whereas the filoviral VP24 proteins and mVP40 are insufficient to prevent DC maturation. IMPORTANCE The ability to suppress the function of dendritic cells (DCs) likely contributes to the pathogenesis of disease caused by the filoviruses Ebola virus and Marburg virus. To clarify the basis for this DC suppression, we assessed the effect of filovirus proteins known to antagonize innate immune signaling pathways, including Ebola virus VP35 and VP24 and Marburg virus VP35, VP40, and VP24, on DC maturation and function. The data demonstrate that the VP35s from Ebola virus and Marburg virus are the major suppressors of DC maturation and that the effects on DCs of the remaining innate immune inhibitors are minor.
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55
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Furuya AKM, Sharifi HJ, Jellinger RM, Cristofano P, Shi B, de Noronha CMC. Sulforaphane Inhibits HIV Infection of Macrophages through Nrf2. PLoS Pathog 2016; 12:e1005581. [PMID: 27093399 PMCID: PMC4836681 DOI: 10.1371/journal.ppat.1005581] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 03/28/2016] [Indexed: 12/18/2022] Open
Abstract
Marburg virus, the Kaposi's sarcoma-associated herpesvirus (KSHV) and Dengue virus all activate, and benefit from, expression of the transcription regulator nuclear erythroid 2-related factor 2 (Nrf2). The impact of Nrf2 activation on human immunodeficiency virus (HIV) infection has not been tested. Sulforaphane (SFN), produced in cruciferous vegetables after mechanical damage, mobilizes Nrf2 to potently reprogram cellular gene expression. Here we show for the first time that SFN blocks HIV infection in primary macrophages but not in primary T cells. Similarly SFN blocks infection in PMA-differentiated promonocytic cell lines, but not in other cell lines tested. siRNA-mediated depletion of Nrf2 boosted HIV infectivity in primary macrophages and reduced the anti-viral effects of SFN treatment. This supports a model in which anti-viral activity is mediated through Nrf2 after it is mobilized by SFN. We further found that, like the type I interferon-induced cellular anti-viral proteins SAMHD1 and MX2, SFN treatment blocks infection after entry, but before formation of 2-LTR circles. Interestingly however, neither SAMHD1 nor MX2 were upregulated. This shows for the first time that Nrf2 action can potently block HIV infection and highlights a novel way to trigger this inhibition. Nrf2 turns on anti-oxidant genes in response to pharmaceuticals like oltipratz, environmental agents like heavy metals and cigarette smoke, endogenous agents like nitrous oxide and nitro-fatty acids and even plant products like sulforaphane (SFN) and epigallocatechin gallate (EGCG). An increasing body of work is showing that some viruses activate and benefit from Nrf2. In this work we tested the impact of Nrf2 on HIV. We used SFN, abundant in cruciferous vegetables and often used as a dietary supplement, to activate Nrf2. Here we show, for the first time, that in immune cells isolated from donor blood, SFN halts HIV infection in macrophages, but not in T cells. We further show that upon SFN treatment the virus is blocked after it has transcribed its RNA-encoded genome into DNA, but before this genetic material is inserted into host chromosomes. Importantly this block is indeed dependent on Nrf2. Interestingly, Nrf2 does not activate recognized anti-viral genes. Thus, unlike viruses recently found to benefit from Nrf2 activation, HIV can be blocked by its activation. This highlights the opportunity to activate a heretofore unrecognized anti-viral function by triggering an antioxidant response with a common dietary component.
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Affiliation(s)
- Andrea Kinga Marias Furuya
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York, United States of America
| | - Hamayun J. Sharifi
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York, United States of America
| | - Robert M. Jellinger
- Division of HIV Medicine, Albany Medical Center, Albany, New York, United States of America
| | - Paul Cristofano
- Albany Medical College, Albany Medical Center, Albany, New York, United States of America
| | - Binshan Shi
- Albany College of Pharmacy and Health Sciences, Albany, New York, United States of America
| | - Carlos M. C. de Noronha
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York, United States of America
- * E-mail:
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56
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Edwards MR, Liu G, Mire CE, Sureshchandra S, Luthra P, Yen B, Shabman RS, Leung DW, Messaoudi I, Geisbert TW, Amarasinghe GK, Basler CF. Differential Regulation of Interferon Responses by Ebola and Marburg Virus VP35 Proteins. Cell Rep 2016; 14:1632-1640. [PMID: 26876165 PMCID: PMC4767585 DOI: 10.1016/j.celrep.2016.01.049] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 12/16/2015] [Accepted: 01/13/2016] [Indexed: 12/31/2022] Open
Abstract
Suppression of innate immune responses during filoviral infection contributes to disease severity. Ebola (EBOV) and Marburg (MARV) viruses each encode a VP35 protein that suppresses RIG-I-like receptor signaling and interferon-α/β (IFN-α/β) production by several mechanisms, including direct binding to double stranded RNA (dsRNA). Here, we demonstrate that in cell culture, MARV infection results in a greater upregulation of IFN responses as compared to EBOV infection. This correlates with differences in the efficiencies by which EBOV and MARV VP35s antagonize RIG-I signaling. Furthermore, structural and biochemical studies suggest that differential recognition of RNA elements by the respective VP35 C-terminal IFN inhibitory domain (IID) rather than affinity for RNA by the respective VP35s is critical for this observation. Our studies reveal functional differences in EBOV versus MARV VP35 RNA binding that result in unexpected differences in the host response to deadly viral pathogens.
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Affiliation(s)
- Megan R Edwards
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Gai Liu
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Chad E Mire
- Department of Microbiology and Immunology, Galveston National Laboratory, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA
| | - Suhas Sureshchandra
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA 92521, USA
| | - Priya Luthra
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Benjamin Yen
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Reed S Shabman
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Virology Group, J. Craig Venter Institute, Rockville, MD 20850, USA
| | - Daisy W Leung
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Ilhem Messaoudi
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA 92521, USA
| | - Thomas W Geisbert
- Department of Microbiology and Immunology, Galveston National Laboratory, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA
| | - Gaya K Amarasinghe
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Christopher F Basler
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
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57
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Komaravelli N, Tian B, Ivanciuc T, Mautemps N, Brasier AR, Garofalo RP, Casola A. Respiratory syncytial virus infection down-regulates antioxidant enzyme expression by triggering deacetylation-proteasomal degradation of Nrf2. Free Radic Biol Med 2015; 88:391-403. [PMID: 26073125 PMCID: PMC4628892 DOI: 10.1016/j.freeradbiomed.2015.05.043] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 05/21/2015] [Accepted: 05/27/2015] [Indexed: 11/23/2022]
Abstract
Respiratory syncytial virus (RSV) is the most important cause of viral acute respiratory tract infections and hospitalizations in children, for which no vaccine or treatment is available. RSV infection in cells, mice, and children leads to rapid generation of reactive oxygen species, which are associated with oxidative stress and lung damage, due to a significant decrease in the expression of airway antioxidant enzymes (AOEs). Oxidative stress plays an important role in the pathogenesis of RSV-induced lung disease, as antioxidants ameliorate clinical disease and inflammation in vivo. The aim of this study is to investigate the unknown mechanism(s) of virus-induced inhibition of AOE expression. RSV infection is shown to induce a progressive reduction in nuclear and total cellular levels of the transcription factor NF-E2-related factor 2 (Nrf2), resulting in decreased binding to endogenous AOE gene promoters and decreased AOE expression. RSV induces Nrf2 deacetylation and degradation via the proteasome pathway in vitro and in vivo. Histone deacetylase and proteasome inhibitors block Nrf2 degradation and increase Nrf2 binding to AOE endogenous promoters, resulting in increased AOE expression. Known inducers of Nrf2 are able to increase Nrf2 activation and subsequent AOE expression during RSV infection in vitro and in vivo, with significant amelioration of oxidative stress. This is the first study to investigate the mechanism(s) of virus-induced inhibition of AOE expression. RSV-induced inhibition of Nrf2 activation, due to deacetylation and proteasomal degradation, could be targeted for therapeutic intervention aimed to increase airway antioxidant capacity during infection.
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Affiliation(s)
- Narayana Komaravelli
- Department of Pediatrics, University of Texas Medical Branch at Galveston, TX 77555, USA
| | - Bing Tian
- Department of Internal Medicine, University of Texas Medical Branch at Galveston, TX 77555, USA
| | - Teodora Ivanciuc
- Department of Pediatrics, University of Texas Medical Branch at Galveston, TX 77555, USA
| | - Nicholas Mautemps
- Department of Pediatrics, University of Texas Medical Branch at Galveston, TX 77555, USA
| | - Allan R Brasier
- Department of Internal Medicine, University of Texas Medical Branch at Galveston, TX 77555, USA; Department of Sealy Center for Molecular Medicine, University of Texas Medical Branch at Galveston, TX 77555, USA
| | - Roberto P Garofalo
- Department of Pediatrics, University of Texas Medical Branch at Galveston, TX 77555, USA
| | - Antonella Casola
- Department of Pediatrics, University of Texas Medical Branch at Galveston, TX 77555, USA; Department of Sealy Center for Molecular Medicine, University of Texas Medical Branch at Galveston, TX 77555, USA.
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58
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Messaoudi I, Amarasinghe GK, Basler CF. Filovirus pathogenesis and immune evasion: insights from Ebola virus and Marburg virus. Nat Rev Microbiol 2015; 13:663-76. [PMID: 26439085 DOI: 10.1038/nrmicro3524] [Citation(s) in RCA: 171] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Ebola viruses and Marburg viruses, members of the filovirus family, are zoonotic pathogens that cause severe disease in people, as highlighted by the latest Ebola virus epidemic in West Africa. Filovirus disease is characterized by uncontrolled virus replication and the activation of host responses that contribute to pathogenesis. Underlying these phenomena is the potent suppression of host innate antiviral responses, particularly the type I interferon response, by viral proteins, which allows high levels of viral replication. In this Review, we describe the mechanisms used by filoviruses to block host innate immunity and discuss the links between immune evasion and filovirus pathogenesis.
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Affiliation(s)
- Ilhem Messaoudi
- School of Medicine, University of California Riverside, Riverside, California 92521, USA
| | - Gaya K Amarasinghe
- The Division of Biology &Biomedical Sciences, Washington University in St. Louis, St. Louis, Missouri 63110, USA
| | - Christopher F Basler
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
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59
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Nrf2 as a master regulator of tissue damage control and disease tolerance to infection. Biochem Soc Trans 2015; 43:663-8. [PMID: 26551709 PMCID: PMC4613525 DOI: 10.1042/bst20150054] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Indexed: 12/29/2022]
Abstract
Damage control refers to those actions made towards minimizing damage or loss. Depending on the context, these can range from emergency procedures dealing with the sinking of a ship or to a surgery dealing with severe trauma or even to an imaginary company in Marvel comics, which repairs damaged property arising from conflicts between super heroes and villains. In the context of host microbe interactions, tissue damage control refers to an adaptive response that limits the extent of tissue damage associated with infection. Tissue damage control can limit the severity of infectious diseases without interfering with pathogen burden, conferring disease tolerance to infection. This contrasts with immune-driven resistance mechanisms, which although essential to protect the host from infection, can impose tissue damage to host parenchyma tissues. This damaging effect is countered by stress responses that confer tissue damage control and disease tolerance to infection. Here we discuss how the stress response regulated by the transcription factor nuclear factor-erythroid 2-related factor 2 (Nrf2) acts in such a manner.
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60
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Basler CF. Innate immune evasion by filoviruses. Virology 2015; 479-480:122-30. [DOI: 10.1016/j.virol.2015.03.030] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Accepted: 03/17/2015] [Indexed: 01/07/2023]
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61
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Edwards MR, Basler CF. Marburg Virus VP24 Protein Relieves Suppression of the NF-κB Pathway Through Interaction With Kelch-like ECH-Associated Protein 1. J Infect Dis 2015; 212 Suppl 2:S154-9. [PMID: 25926686 DOI: 10.1093/infdis/jiv050] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Marburg virus (MARV) is an emerging zoonotic pathogen that causes hemorrhagic fever. MARV VP24 (mVP24) protein interacts with the host cell protein Kelch-like-ECH-associated protein 1 (Keap1). Keap1 interacts with and promotes the degradation of IκB kinase β (IKKβ), a component of the IκB kinase (IKK) complex that regulates nuclear factor-κB (NF-κB) activity. We studied whether mVP24 could relieve Keap1 repression of the NF-κB pathway. METHODS Coimmunoprecipitation assays were used to examine the interaction between Keap1 and IKKβ in the presence of wild-type mVP24 and mutants of mVP24 defective for binding to Keap1. Western blotting was used to determine levels of IKKβ expression in the presence of Keap1 and mVP24. NF-κB promoter-luciferase assays were used to determine the effect of mVP24 on Keap1-induced repression of activity. RESULTS Expression of wild-type mVP24 disrupted the interaction of IKKβ and Keap1, whereas weakly interacting and noninteracting mVP24 mutants did not disrupt the interaction between Keap1 and IKKβ. The interaction of mVP24 with Keap1 enhanced IKKβ levels in the presence of Keap1. The interaction of mVP24 with Keap1 also relieved Keap1 repression of NF-κB reporter activity. CONCLUSIONS mVP24 can relieve Keap1 repression of the NF-κB pathway through its interaction with Keap1.
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Affiliation(s)
- Megan R Edwards
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Christopher F Basler
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York
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62
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Reynard O, Escudero-Perez B, Volchkov V. [Haemostasis dysregulation in filovirus infections]. Med Sci (Paris) 2015; 31:143-50. [PMID: 25744260 DOI: 10.1051/medsci/20153102010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Filoviruses are responsible for highly lethal infections. Those viruses are found in intertropical areas of Africa and Asia where they circulate in their supposed natural reservoir, fruit bats. During filovirus outbreaks and depending on the strains, various modifications in hemostasis have been observed in patients. The disseminated intravascular coagulation identified in these infections is multicausal and involves both viral factors and abnormal physiological responses. In this review we will describe the mechanisms responsible for these disturbances and we will highlight some aspects of the basis of filovirus high pathogenicity.
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Affiliation(s)
- Olivier Reynard
- CIRI (centre international de recherche en infectiologie), Inserm U1111, laboratoire bases moléculaires de la pathogénicité virale, 21, avenue Tony Garnier, 69007 Lyon, France
| | - Beatriz Escudero-Perez
- CIRI (centre international de recherche en infectiologie), Inserm U1111, laboratoire bases moléculaires de la pathogénicité virale, 21, avenue Tony Garnier, 69007 Lyon, France
| | - Viktor Volchkov
- CIRI (centre international de recherche en infectiologie), Inserm U1111, laboratoire bases moléculaires de la pathogénicité virale, 21, avenue Tony Garnier, 69007 Lyon, France
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63
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Kajihara M, Takada A. Host Cell Factors Involved in Filovirus Infection. CURRENT TROPICAL MEDICINE REPORTS 2015. [DOI: 10.1007/s40475-015-0039-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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64
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Albariño CG, Wiggleton Guerrero L, Spengler JR, Uebelhoer LS, Chakrabarti AK, Nichol ST, Towner JS. Recombinant Marburg viruses containing mutations in the IID region of VP35 prevent inhibition of Host immune responses. Virology 2014; 476:85-91. [PMID: 25531184 PMCID: PMC6461211 DOI: 10.1016/j.virol.2014.12.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 11/22/2014] [Accepted: 12/02/2014] [Indexed: 12/02/2022]
Abstract
Previous in vitro studies have demonstrated that Ebola and Marburg virus (EBOV and MARV) VP35 antagonize the host cell immune response. Moreover, specific mutations in the IFN inhibitory domain (IID) of EBOV and MARV VP35 that abrogate their interaction with virus-derived dsRNA, lack the ability to inhibit the host immune response. To investigate the role of MARV VP35 in the context of infectious virus, we used our reverse genetics system to generate two recombinant MARVs carrying specific mutations in the IID region of VP35. Our data show that wild-type and mutant viruses grow to similar titers in interferon deficient cells, but exhibit attenuated growth in interferon-competent cells. Furthermore, in contrast to wild-type virus, both MARV mutants were unable to inhibit expression of various antiviral genes. The MARV VP35 mutants exhibit similar phenotypes to those previously described for EBOV, suggesting the existence of a shared immune-modulatory strategy between filoviruses.
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65
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Cellular oxidative stress response controls the antiviral and apoptotic programs in dengue virus-infected dendritic cells. PLoS Pathog 2014; 10:e1004566. [PMID: 25521078 PMCID: PMC4270780 DOI: 10.1371/journal.ppat.1004566] [Citation(s) in RCA: 170] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 11/10/2014] [Indexed: 12/14/2022] Open
Abstract
Dengue virus (DENV) is a re-emerging arthropod borne flavivirus that infects more than 300 million people worldwide, leading to 50,000 deaths annually. Because dendritic cells (DC) in the skin and blood are the first target cells for DENV, we sought to investigate the early molecular events involved in the host response to the virus in primary human monocyte-derived dendritic cells (Mo-DC). Using a genome-wide transcriptome analysis of DENV2-infected human Mo-DC, three major responses were identified within hours of infection - the activation of IRF3/7/STAT1 and NF-κB-driven antiviral and inflammatory networks, as well as the stimulation of an oxidative stress response that included the stimulation of an Nrf2-dependent antioxidant gene transcriptional program. DENV2 infection resulted in the intracellular accumulation of reactive oxygen species (ROS) that was dependent on NADPH-oxidase (NOX). A decrease in ROS levels through chemical or genetic inhibition of the NOX-complex dampened the innate immune responses to DENV infection and facilitated DENV replication; ROS were also essential in driving mitochondrial apoptosis in infected Mo-DC. In addition to stimulating innate immune responses to DENV, increased ROS led to the activation of bystander Mo-DC which up-regulated maturation/activation markers and were less susceptible to viral replication. We have identified a critical role for the transcription factor Nrf2 in limiting both antiviral and cell death responses to the virus by feedback modulation of oxidative stress. Silencing of Nrf2 by RNA interference increased DENV-associated immune and apoptotic responses. Taken together, these data demonstrate that the level of oxidative stress is critical to the control of both antiviral and apoptotic programs in DENV-infected human Mo-DC and highlight the importance of redox homeostasis in the outcome of DENV infection. Dengue virus (DENV), the leading arthropod-borne viral infection in the world, represents a major human health concern with a global at risk population of over 3 billion people. Currently, there are no antivirals or vaccines available to treat patients with dengue fever, nor is it possible to predict which patients will progress to life-threatening severe dengue fever. Markers associated with oxidative stress responses have been reported in patients with severe DENV infection, suggesting a relationship between oxidative stress and viral pathogenesis. In order to uncover biological processes that determine the outcome of disease in patients, we utilized human dendritic cells, the primary target of DENV infection, in an in vitro model. Transcriptional analysis of pathways activated upon de novo DENV infection revealed a major role for cellular oxidative stress in the induction of antiviral, inflammatory, and cell death responses. We also demonstrated that antioxidant mechanisms play a critical role in controlling antiviral and cell death responses to the virus, acting as feedback regulators of the oxidative stress response. This report highlights the importance of oxidative stress responses in the outcome of DENV infection, and identifies this pathway as a potential new entry-point for treating dengue-associated diseases.
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Kaposi's sarcoma-associated herpesvirus induces Nrf2 activation in latently infected endothelial cells through SQSTM1 phosphorylation and interaction with polyubiquitinated Keap1. J Virol 2014; 89:2268-86. [PMID: 25505069 DOI: 10.1128/jvi.02742-14] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
UNLABELLED Nuclear factor erythroid 2-related factor 2 (Nrf2), the cellular master regulator of the antioxidant response, dissociates from its inhibitor Keap1 when activated by stress signals and participates in the pathogenesis of viral infections and tumorigenesis. Early during de novo infection of endothelial cells, KSHV induces Nrf2 through an intricate mechanism involving reactive oxygen species (ROS) and prostaglandin E2 (PGE2). When we investigated the Nrf2 activity during latent KSHV infection, we observed increased nuclear serine-40-phosphorylated Nrf2 in human KS lesions compared to that in healthy tissues. Using KSHV long-term-infected endothelial cells (LTC) as a cellular model for KS, we demonstrated that KSHV infection induces Nrf2 constitutively by extending its half-life, increasing its phosphorylation by protein kinase Cζ (PKCζ) via the infection-induced cyclooxygenase-2 (COX-2)/PGE2 axis and inducing its nuclear localization. Nrf2 knockdown in LTC decreased expression of antioxidant genes and genes involved in KS pathogenesis such as the NAD(P)H quinone oxidase 1 (NQO1), gamma glutamylcysteine synthase heavy unit (γGCSH), the cysteine transporter (xCT), interleukin 6 (IL-6), and vascular endothelial growth factor A (VEGF-A) genes. Nrf2 activation was independent of oxidative stress but dependent on the autophagic protein sequestosome-1 (SQSTM1; p62). SQSTM1 levels were elevated in LTC, a consequence of protein accumulation due to decreased autophagy and Nrf2-mediated transcriptional activation. SQSTM1 was phosphorylated on serine-351 and -403, while Keap1 was polyubiquitinated with lysine-63-ubiquitin chains, modifications known to increase their mutual affinity and interaction, leading to Keap1 degradation and Nrf2 activation. The latent KSHV protein Fas-associated death domain-like interleukin-1β-converting enzyme-inhibitory protein (vFLIP) increased SQSTM1 expression and activated Nrf2. Collectively, these results demonstrate that KSHV induces SQSTM1 to constitutively activate Nrf2, which is involved in the regulation of genes participating in KSHV oncogenesis. IMPORTANCE The transcription factor Nrf2 is activated by stress signals, including viral infection, and responds by activating the transcription of cytoprotective genes. Recently, Nrf2 has been implicated in oncogenesis and was shown to be activated during de novo KSHV infection of endothelial cells through ROS-dependent pathways. The present study was undertaken to determine the mechanism of Nrf2 activation during prolonged latent infection of endothelial cells, using an endothelial cell line latently infected with KSHV. We show that Nrf2 activation was elevated in KSHV latently infected endothelial cells independently of oxidative stress but dependent on the autophagic protein sequestosome-1 (SQSTM1), which was involved in the degradation of the Nrf2 inhibitor Keap1. Furthermore, our results indicated that the KSHV latent protein vFLIP participates in Nrf2 activation. This study suggests that KSHV hijacks the host's autophagic protein SQSTM1 to induce Nrf2 activation, thereby manipulating the infected host gene regulation to promote KS pathogenesis.
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Gjyshi O, Bottero V, Veettil MV, Dutta S, Singh VV, Chikoti L, Chandran B. Kaposi's sarcoma-associated herpesvirus induces Nrf2 during de novo infection of endothelial cells to create a microenvironment conducive to infection. PLoS Pathog 2014; 10:e1004460. [PMID: 25340789 PMCID: PMC4207826 DOI: 10.1371/journal.ppat.1004460] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Accepted: 09/10/2014] [Indexed: 12/30/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiological agent of Kaposi's sarcoma (KS) and primary effusion B-cell lymphoma. KSHV induces reactive oxygen species (ROS) early during infection of human dermal microvascular endothelial (HMVEC-d) cells that are critical for virus entry. One of the downstream targets of ROS is nuclear factor E2-related factor 2 (Nrf2), a transcription factor with important anti-oxidative functions. Here, we show that KS skin lesions have high Nrf2 activity compared to healthy skin tissue. Within 30 minutes of de novo KSHV infection of HMVEC-d cells, we observed Nrf2 activation through ROS-mediated dissociation from its inhibitor Keap1, Ser-40 phosphorylation, and subsequent nuclear translocation. KSHV binding and consequent signaling through Src, PI3-K and PKC-ζ were also important for Nrf2 stability, phosphorylation and transcriptional activity. Although Nrf2 was dispensable for ROS homeostasis, it was essential for the induction of COX-2, VEGF-A, VEGF-D, Bcl-2, NQO1, GCS, HO1, TKT, TALDO and G6PD gene expression in KSHV-infected HMVEC-d cells. The COX-2 product PGE2 induced Nrf2 activity through paracrine and autocrine signaling, creating a feed-forward loop between COX-2 and Nrf2. vFLIP, a product of KSHV latent gene ORF71, induced Nrf2 and its target genes NQO1 and HO1. Activated Nrf2 colocalized with the KSHV genome as well as with the latency protein LANA-1. Nrf2 knockdown enhanced ORF73 expression while reducing ORF50 and other lytic gene expression without affecting KSHV entry or genome nuclear delivery. Collectively, these studies for the first time demonstrate that during de novo infection, KSHV induces Nrf2 through intricate mechanisms involving multiple signal molecules, which is important for its ability to manipulate host and viral genes, creating a microenvironment conducive to KSHV infection. Thus, Nrf2 is a potential attractive target to intervene in KSHV infection and the associated maladies. KSHV infection of endothelial cells in vivo causes Kaposi's sarcoma and understanding the steps involved in de novo KSHV infection of these cells and the consequences is important to develop therapies to counter KSHV pathogenesis. Infection of endothelial cells in vitro is preceded by the induction of a network of host signaling agents that are necessary for virus entry, gene expression and establishment of latency. Our previous studies have implicated reactive oxygen species (ROS) as part of this network. In the current study, we show that ROS activate Nrf2, a master transcriptional regulator of genes involved in ROS homeostasis, apoptosis, glucose metabolism and angiogenesis. Besides ROS, KSHV utilizes additional aspects of host signaling to induce Nrf2 activity. We also observed that infection of endothelial cells deficient in Nrf2 resulted in downregulation of multiple genes important in KSHV pathogenesis, such as COX-2 and VEGF, and affected proper expression of two hallmark KSHV genes, lytic ORF50 and latent ORF73. Taken together, this study is the first to demonstrate the importance of Nrf2 during de novo KSHV infection of endothelial cells, and establishes Nrf2 as an attractive therapeutic target to control KSHV infection, establishment of latency and the associated cancers.
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Affiliation(s)
- Olsi Gjyshi
- H. M. Bligh Cancer Research Laboratories, Department of Microbiology and Immunology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, United States of America
| | - Virginie Bottero
- H. M. Bligh Cancer Research Laboratories, Department of Microbiology and Immunology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, United States of America
| | - Mohanan Valliya Veettil
- H. M. Bligh Cancer Research Laboratories, Department of Microbiology and Immunology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, United States of America
| | - Sujoy Dutta
- H. M. Bligh Cancer Research Laboratories, Department of Microbiology and Immunology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, United States of America
| | - Vivek Vikram Singh
- H. M. Bligh Cancer Research Laboratories, Department of Microbiology and Immunology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, United States of America
| | - Leela Chikoti
- H. M. Bligh Cancer Research Laboratories, Department of Microbiology and Immunology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, United States of America
| | - Bala Chandran
- H. M. Bligh Cancer Research Laboratories, Department of Microbiology and Immunology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, United States of America
- * E-mail:
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Hybertson BM, Gao B. Role of the Nrf2 signaling system in health and disease. Clin Genet 2014; 86:447-52. [PMID: 25099075 DOI: 10.1111/cge.12474] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Revised: 07/22/2014] [Accepted: 07/28/2014] [Indexed: 12/17/2022]
Abstract
A key component of cytoprotective gene regulation is the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), also known as nuclear factor erythroid 2-like 2, from the gene NFE2L2. Under normal conditions, Nrf2 in the cell is targeted for proteasomal degradation by its inhibitor Kelch-like ECH-associated inhibitor 1 (Keap1). When stimulated by oxidative stress, electrophiles, or kinase activation, conformational changes in the Nrf2-Keap1 complex inhibit proteasomal degradation of Nrf2, facilitating an increase in the amount of Nrf2 that binds to antioxidant response element sequences in the promoter regions of a variety of antioxidant, detoxification, and metabolic control genes. Nrf2 activation is mostly associated with beneficial cytoprotective gene regulation, but it can also have deleterious effects. For example, gene mutations in some types of cancers can lead to constitutive activation of Nrf2 and give the tumor cells growth advantages and increased drug resistance. Because cases exist where Nrf2/Keap1/ARE signaling is either too low or too high, there is great interest in the development of both Nrf2 activators and Nrf2 inhibitors as the basis of new therapies.
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Affiliation(s)
- B M Hybertson
- Department of Medicine, Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
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Yang JJ, Tao H, Hu W, Liu LP, Shi KH, Deng ZY, Li J. MicroRNA-200a controls Nrf2 activation by target Keap1 in hepatic stellate cell proliferation and fibrosis. Cell Signal 2014; 26:2381-9. [PMID: 25049078 DOI: 10.1016/j.cellsig.2014.07.016] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 07/09/2014] [Indexed: 01/19/2023]
Abstract
Hepatic fibrosis is a common final pathological process in the progression of liver disease, which is primarily due to oxidative stress. Nrf2 is known to coordinate induction of genes that encode antioxidant enzymes. Moreover, Nrf2 expression is largely regulated through the association of Nrf2 with Keap1, which results in cytoplasmic Nrf2 degradation. Conversely, little is known concerning the regulation of Keap1 expression. Although the function of miRNA-200a controls Keap1 gene expression has been discussed in many cancers and fibrotic diseases, its role in hepatic fibrosis is still poorly understood. By using miRNA mimic, we observed miRNA-200a silencing in activated hepatic stellate cell and demonstrated that upon re-expression, miRNA-200a targets the Keap1, and leading to Keap1 mRNA degradation. We find that treatment with miRNA-200a mimics, restored miRNA-200a expression and reduced Keap1 levels. This reduction in Keap1 levels corresponded with Nrf2 nuclear translocation and activation of Nrf2-dependent NQO1 gene transcription. Moreover, we found that Nrf2 activation inhibited the TGF-β1-independent growth of hepatic stellate cell. Finally, our study demonstrates that miRNA-200a regulates the Keap1/Nrf2 pathway in hepatic stellate cell and fibrosis, and we find that epigenetic therapy can restore miRNA-200a regulation of Keap1 expression, therefore reactivating the Nrf2-dependent antioxidant pathway in liver fibrosis.
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Affiliation(s)
- Jing-Jing Yang
- Department of Pharmacology, The Second Hospital of Anhui Medical University, Hefei 230601, China
| | - Hui Tao
- Department of Cardiothoracic Surgery, The Second Hospital of Anhui Medical University, Hefei 230601, China
| | - Wei Hu
- Department of Pharmacology, The Second Hospital of Anhui Medical University, Hefei 230601, China
| | - Li-Ping Liu
- Department of Pharmacology, The Second Hospital of Anhui Medical University, Hefei 230601, China
| | - Kai-Hu Shi
- Department of Cardiothoracic Surgery, The Second Hospital of Anhui Medical University, Hefei 230601, China
| | - Zi-Yu Deng
- Department of Scientific and Educational, The Second Hospital of Anhui Medical University, China
| | - Jun Li
- School of Pharmacy, Anhui Medical University, Hefei 230032, China.
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Du Toit A. Marburg targets the host oxidative response. Nat Rev Microbiol 2014; 12:311. [DOI: 10.1038/nrmicro3258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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