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Tang M, Xia W, Song F, Liu C, Wang X, Zhou H, Mai K, He G. Loss of Gcn2 exacerbates gossypol induced oxidative stress, apoptosis and inflammation in zebrafish. FISH & SHELLFISH IMMUNOLOGY 2024; 151:109727. [PMID: 38936520 DOI: 10.1016/j.fsi.2024.109727] [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: 03/27/2024] [Revised: 06/22/2024] [Accepted: 06/24/2024] [Indexed: 06/29/2024]
Abstract
Gossypol, a naturally occurring compound found in cottonseed meal, shows promising therapeutic potential for human diseases. However, within the aquaculture industry, it is considered an antinutritional factor. The incorporation of cottonseed meal into fish feed introduces gossypol, which induces intracellular stresses and hinders overall health of farmed fish. The aim of this study is to determine the role of General control nonderepressible 2 (gcn2), a sensor for intracellular stresses in gossypol-induced stress responses in fish. In the present study, we established two gcn2 knockout zebrafish lines. A feeding trial was conducted to assess the growth-inhibitory effect of gossypol in both wild type and gcn2 knockout zebrafish. The results showed that in the absence of gcn2, zebrafish exhibited increased oxidative stress and apoptosis when exposed to gossypol, resulting in higher mortality rates. In feeding trial, dietary gossypol intensified liver inflammation in gcn2-/- zebrafish, diminishing their growth and feed conversion. Remarkably, administering the antioxidant N-acetylcysteine (NAC) was effective in reversing the gossypol induced oxidative stress and apoptosis, thereby increasing the gossypol tolerance of gcn2-/- zebrafish. Exposure to gossypol induces more severe mitochondrial stress in gcn2-/- zebrafish, thereby inducing metabolic disorders. These results reveal that gcn2 plays a protective role in reducing gossypol-induced oxidative stress and apoptosis, attenuating inflammation responses, and enhancing the survivability of zebrafish in gossypol-challenged conditions. Therefore, maintaining appropriate activation of Gcn2 may be beneficial for fish fed diets containing gossypol.
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Affiliation(s)
- Mingjun Tang
- Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, 266003, China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266003, China
| | - Weiyi Xia
- Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, 266003, China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266003, China
| | - Fei Song
- School of Life Sciences, South China Normal University, Guangzhou, 510631, China
| | - Chengdong Liu
- Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, 266003, China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266003, China.
| | - Xuan Wang
- Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, 266003, China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266003, China
| | - Huihui Zhou
- Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, 266003, China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266003, China
| | - Kangsen Mai
- Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, 266003, China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266003, China
| | - Gen He
- Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, 266003, China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266003, China; Key Laboratory of Aquaculture Nutrition and Feeds, Ministry of Agriculture, Ocean University of China, Qingdao, 266003, China
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2
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Gibbs VJ, Lin YH, Ghuge AA, Anderson RA, Schiemann AH, Conaglen L, Sansom BJM, da Silva RC, Sattlegger E. GCN2 in Viral Defence and the Subversive Tactics Employed by Viruses. J Mol Biol 2024; 436:168594. [PMID: 38724002 DOI: 10.1016/j.jmb.2024.168594] [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: 03/13/2024] [Revised: 05/01/2024] [Accepted: 05/01/2024] [Indexed: 06/10/2024]
Abstract
The recent SARS-CoV-2 pandemic and associated COVID19 disease illustrates the important role of viral defence mechanisms in ensuring survival and recovery of the host or patient. Viruses absolutely depend on the host's protein synthesis machinery to replicate, meaning that impeding translation is a powerful way to counteract viruses. One major approach used by cells to obstruct protein synthesis is to phosphorylate the alpha subunit of eukaryotic translation initiation factor 2 (eIF2α). Mammals possess four different eIF2α-kinases: PKR, HRI, PEK/PERK, and GCN2. While PKR is currently considered the principal eIF2α-kinase involved in viral defence, the other eIF2α-kinases have also been found to play significant roles. Unsurprisingly, viruses have developed mechanisms to counteract the actions of eIF2α-kinases, or even to exploit them to their benefit. While some of these virulence factors are specific to one eIF2α-kinase, such as GCN2, others target all eIF2α-kinases. This review critically evaluates the current knowledge of viral mechanisms targeting the eIF2α-kinase GCN2. A detailed and in-depth understanding of the molecular mechanisms by which viruses evade host defence mechanisms will help to inform the development of powerful anti-viral measures.
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Affiliation(s)
- Victoria J Gibbs
- School of Food Technology and Natural Sciences, Massey University, Palmerston North, New Zealand
| | - Yu H Lin
- School of Food Technology and Natural Sciences, Massey University, Palmerston North, New Zealand
| | - Aditi A Ghuge
- School of Food Technology and Natural Sciences, Massey University, Palmerston North, New Zealand
| | - Reuben A Anderson
- School of Food Technology and Natural Sciences, Massey University, Palmerston North, New Zealand
| | - Anja H Schiemann
- School of Food Technology and Natural Sciences, Massey University, Palmerston North, New Zealand
| | - Layla Conaglen
- School of Food Technology and Natural Sciences, Massey University, Palmerston North, New Zealand
| | - Bianca J M Sansom
- School of Natural Sciences, Massey University, Auckland, New Zealand
| | - Richard C da Silva
- School of Natural Sciences, Massey University, Auckland, New Zealand; Genome Biology and Epigenetics, Department of Biology, Utrecht University, Utrecht, the Netherlands
| | - Evelyn Sattlegger
- School of Food Technology and Natural Sciences, Massey University, Palmerston North, New Zealand; School of Natural Sciences, Massey University, Auckland, New Zealand; Maurice Wilkins Centre for Molecular BioDiscovery, Palmerston North, New Zealand.
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3
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Grandgenett DP, Engelman AN. Brief Histories of Retroviral Integration Research and Associated International Conferences. Viruses 2024; 16:604. [PMID: 38675945 PMCID: PMC11054761 DOI: 10.3390/v16040604] [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: 03/19/2024] [Revised: 04/05/2024] [Accepted: 04/10/2024] [Indexed: 04/28/2024] Open
Abstract
The field of retroviral integration research has a long history that started with the provirus hypothesis and subsequent discoveries of the retroviral reverse transcriptase and integrase enzymes. Because both enzymes are essential for retroviral replication, they became valued targets in the effort to discover effective compounds to inhibit HIV-1 replication. In 2007, the first integrase strand transfer inhibitor was licensed for clinical use, and subsequently approved second-generation integrase inhibitors are now commonly co-formulated with reverse transcriptase inhibitors to treat people living with HIV. International meetings specifically focused on integrase and retroviral integration research first convened in 1995, and this paper is part of the Viruses Special Issue on the 7th International Conference on Retroviral Integration, which was held in Boulder Colorado in the summer of 2023. Herein, we overview key historical developments in the field, especially as they pertain to the development of the strand transfer inhibitor drug class. Starting from the mid-1990s, research advancements are presented through the lens of the international conferences. Our overview highlights the impact that regularly scheduled, subject-specific international meetings can have on community-building and, as a result, on field-specific collaborations and scientific advancements.
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Affiliation(s)
- Duane P. Grandgenett
- Department of Molecular Microbiology and Immunology, School of Medicine, Saint Louis University, St. Louis, MO 63104, USA
| | - Alan N. Engelman
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
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4
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Corne A, Adolphe F, Estaquier J, Gaumer S, Corsi JM. ATF4 Signaling in HIV-1 Infection: Viral Subversion of a Stress Response Transcription Factor. BIOLOGY 2024; 13:146. [PMID: 38534416 DOI: 10.3390/biology13030146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2024] [Revised: 02/13/2024] [Accepted: 02/20/2024] [Indexed: 03/28/2024]
Abstract
Cellular integrated stress response (ISR), the mitochondrial unfolded protein response (UPRmt), and IFN signaling are associated with viral infections. Activating transcription factor 4 (ATF4) plays a pivotal role in these pathways and controls the expression of many genes involved in redox processes, amino acid metabolism, protein misfolding, autophagy, and apoptosis. The precise role of ATF4 during viral infection is unclear and depends on cell hosts, viral agents, and models. Furthermore, ATF4 signaling can be hijacked by pathogens to favor viral infection and replication. In this review, we summarize the ATF4-mediated signaling pathways in response to viral infections, focusing on human immunodeficiency virus 1 (HIV-1). We examine the consequences of ATF4 activation for HIV-1 replication and reactivation. The role of ATF4 in autophagy and apoptosis is explored as in the context of HIV-1 infection programmed cell deaths contribute to the depletion of CD4 T cells. Furthermore, ATF4 can also participate in the establishment of innate and adaptive immunity that is essential for the host to control viral infections. We finally discuss the putative role of the ATF4 paralogue, named ATF5, in HIV-1 infection. This review underlines the role of ATF4 at the crossroads of multiple processes reflecting host-pathogen interactions.
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Affiliation(s)
- Adrien Corne
- Laboratoire de Génétique et Biologie Cellulaire, Université Versailles-Saint-Quentin-en-Yvelines, Université Paris-Saclay, 78000 Versailles, France
- CHU de Québec Research Center, Laval University, Quebec City, QC G1V 4G2, Canada
| | - Florine Adolphe
- Laboratoire de Génétique et Biologie Cellulaire, Université Versailles-Saint-Quentin-en-Yvelines, Université Paris-Saclay, 78000 Versailles, France
| | - Jérôme Estaquier
- CHU de Québec Research Center, Laval University, Quebec City, QC G1V 4G2, Canada
- INSERM U1124, Université Paris Cité, 75006 Paris, France
| | - Sébastien Gaumer
- Laboratoire de Génétique et Biologie Cellulaire, Université Versailles-Saint-Quentin-en-Yvelines, Université Paris-Saclay, 78000 Versailles, France
| | - Jean-Marc Corsi
- Laboratoire de Génétique et Biologie Cellulaire, Université Versailles-Saint-Quentin-en-Yvelines, Université Paris-Saclay, 78000 Versailles, France
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5
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Depletion of HIV reservoir by activation of ISR signaling in resting CD4 +T cells. iScience 2023; 26:105743. [PMID: 36590168 PMCID: PMC9800255 DOI: 10.1016/j.isci.2022.105743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 10/21/2022] [Accepted: 12/02/2022] [Indexed: 12/13/2022] Open
Abstract
HIV reservoirs are extremely stable and pose a tremendous challenge to clear HIV infection. Here, we demonstrate that activation of ISR/ATF4 signaling reverses HIV latency, which also selectively eliminates HIV+ cells in primary CD4+T cell model of latency without effect on HIV-negative CD4+T cells. The reduction of HIV+ cells is associated with apoptosis enhancement, but surprisingly is largely seen in HIV-infected cells in which gag-pol RNA transcripts are detected in HIV RNA-induced ATF4/IFIT signaling. In resting CD4+ (rCD4+) T cells isolated from people living with HIV on antiretroviral therapy, induction of ISR/ATF4 signaling reduced HIV reservoirs by depletion of replication-competent HIV without global reduction in the rCD4+ T cell population. These findings suggest that compromised ISR/ATF4 signaling maintains stable and quiescent HIV reservoirs whereas activation of ISR/ATF4 signaling results in the disruption of latent HIV and clearance of persistently infected CD4+T cells.
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Liu WB, Zhu HL, Xiong YW, Lv J, Huang YC, Wang H. Environmental cadmium exposure during gestation impairs fetal brain and cognitive function of adult offspring via reducing placenta-derived E2 level. CHEMOSPHERE 2022; 307:135668. [PMID: 35835241 DOI: 10.1016/j.chemosphere.2022.135668] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Revised: 06/21/2022] [Accepted: 07/08/2022] [Indexed: 06/15/2023]
Abstract
Early-life exposure to environmental cadmium (Cd) is known to cause developmental disorders, yet the effect and mechanism of gestational exposure to Cd on the offspring's cognitive function remains unclear. Placenta as a well-established target organ for Cd-impaired fetal development, its role in estrogen regulation and offspring cognitive function is unknown. Our in vivo experiments found that gestational Cd exposure impaired cognitive function in adult male offspring, accompanied with lowered 17β-estradiol (E2) level in the male fetal brain upon Cd exposure. Correspondingly, the expression of synapse-associated proteins including brain-derived neurotrophic factor (BDNF), post-synaptic density protein 95 (PSD95) and synapsin-1 were downregulated, which were reversed when supplemented with E2 hormone during gestation. Further observation showed placental estrogen synthesis inhibition and general control non-derepressible 2 (GCN2) signaling activation upon Cd exposure, whereas placental estrogen synthesis could be restored through inhibiting GCN2 activity. Based on ovariectomy (OVX) of pregnant mice, we confirmed that Cd exposure reduced E2 level in fetal brain via inhibiting placenta-derived estrogen synthesis. The aforementioned Cd-induced fetal brain injury and cognitive impairment in adult offspring were significantly alleviated when pregnant dams were supplemented with anti-stress agent N-Acetyl-l-cysteine. In summary, Cd disrupted placenta-derived estrogen synthesis via activating GCN2 signaling, and thereby caused cognitive impairment in adult offspring mice. Our findings suggest that placenta-derived estrogen may be an effect marker of environmental toxicants-evoked cognitive dysfunction in adult offspring and suggest that environmental toxicants may affect the fetal brain development via placenta-fetal-brain axis.
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Affiliation(s)
- Wei-Bo Liu
- Department of Toxicology, School of Public Health, Anhui Medical University, China; Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes, China; Key Laboratory of Population Health Across Life Cycle, Anhui Medical University, Ministry of Education of the People's Republic of China, China
| | - Hua-Long Zhu
- Department of Toxicology, School of Public Health, Anhui Medical University, China; Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes, China; Key Laboratory of Population Health Across Life Cycle, Anhui Medical University, Ministry of Education of the People's Republic of China, China
| | - Yong-Wei Xiong
- Department of Toxicology, School of Public Health, Anhui Medical University, China; Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes, China; Key Laboratory of Population Health Across Life Cycle, Anhui Medical University, Ministry of Education of the People's Republic of China, China
| | - Jia Lv
- Department of Toxicology, School of Public Health, Anhui Medical University, China; Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes, China
| | - Yi-Chao Huang
- Department of Toxicology, School of Public Health, Anhui Medical University, China; Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes, China
| | - Hua Wang
- Department of Toxicology, School of Public Health, Anhui Medical University, China; Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes, China; Key Laboratory of Population Health Across Life Cycle, Anhui Medical University, Ministry of Education of the People's Republic of China, China.
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7
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Complex Relationships between HIV-1 Integrase and Its Cellular Partners. Int J Mol Sci 2022; 23:ijms232012341. [PMID: 36293197 PMCID: PMC9603942 DOI: 10.3390/ijms232012341] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 10/09/2022] [Accepted: 10/11/2022] [Indexed: 11/06/2022] Open
Abstract
RNA viruses, in pursuit of genome miniaturization, tend to employ cellular proteins to facilitate their replication. HIV-1, one of the most well-studied retroviruses, is not an exception. There is numerous evidence that the exploitation of cellular machinery relies on nucleic acid-protein and protein-protein interactions. Apart from Vpr, Vif, and Nef proteins that are known to regulate cellular functioning via interaction with cell components, another viral protein, integrase, appears to be crucial for proper virus-cell dialog at different stages of the viral life cycle. The goal of this review is to summarize and systematize existing data on known cellular partners of HIV-1 integrase and their role in the HIV-1 life cycle.
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Rocchi C, Gouet P, Parissi V, Fiorini F. The C-Terminal Domain of HIV-1 Integrase: A Swiss Army Knife for the Virus? Viruses 2022; 14:v14071397. [PMID: 35891378 PMCID: PMC9316232 DOI: 10.3390/v14071397] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 06/22/2022] [Accepted: 06/22/2022] [Indexed: 12/31/2022] Open
Abstract
Retroviral integrase is a multimeric enzyme that catalyzes the integration of reverse-transcribed viral DNA into the cellular genome. Beyond integration, the Human immunodeficiency virus type 1 (HIV-1) integrase is also involved in many other steps of the viral life cycle, such as reverse transcription, nuclear import, virion morphogenesis and proviral transcription. All these additional functions seem to depend on the action of the integrase C-terminal domain (CTD) that works as a molecular hub, interacting with many different viral and cellular partners. In this review, we discuss structural issues concerning the CTD, with particular attention paid to its interaction with nucleic acids. We also provide a detailed map of post-translational modifications and interaction with molecular partners.
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Affiliation(s)
- Cecilia Rocchi
- Molecular Microbiology and Structural Biochemistry (MMSB), CNRS, University of Lyon 1, UMR 5086, 69367 Lyon, France; (C.R.); (P.G.)
- Viral DNA Integration and Chromatin Dynamics Network (DyNAVir), 33076 Bordeaux, France;
| | - Patrice Gouet
- Molecular Microbiology and Structural Biochemistry (MMSB), CNRS, University of Lyon 1, UMR 5086, 69367 Lyon, France; (C.R.); (P.G.)
- Viral DNA Integration and Chromatin Dynamics Network (DyNAVir), 33076 Bordeaux, France;
| | - Vincent Parissi
- Viral DNA Integration and Chromatin Dynamics Network (DyNAVir), 33076 Bordeaux, France;
- Fundamental Microbiology and Pathogenicity (MFP), CNRS, University of Bordeaux, UMR5234, 33405 Bordeaux, France
| | - Francesca Fiorini
- Molecular Microbiology and Structural Biochemistry (MMSB), CNRS, University of Lyon 1, UMR 5086, 69367 Lyon, France; (C.R.); (P.G.)
- Viral DNA Integration and Chromatin Dynamics Network (DyNAVir), 33076 Bordeaux, France;
- Correspondence: ; Tel.: +33-4-72722624; Fax: +33-4-72722616
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Targeting the Integrated Stress Response Kinase GCN2 to Modulate Retroviral Integration. Molecules 2021; 26:molecules26175423. [PMID: 34500856 PMCID: PMC8434491 DOI: 10.3390/molecules26175423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 09/01/2021] [Accepted: 09/04/2021] [Indexed: 11/16/2022] Open
Abstract
Multiple viral targets are now available in the clinic to fight HIV infection. Even if this targeted therapy is highly effective at suppressing viral replication, caregivers are facing growing therapeutic failures in patients due to resistance, with or without treatment-adherence glitches. Accordingly, it is important to better understand how HIV and other retroviruses replicate in order to propose alternative antiviral strategies. Recent studies have shown that multiple cellular factors are implicated during the integration step and, more specifically, that integrase can be regulated through post-translational modifications. We have shown that integrase is phosphorylated by GCN2, a cellular protein kinase of the integrated stress response, leading to a restriction of HIV replication. In addition, we found that this mechanism is conserved among other retroviruses. Accordingly, we developed an in vitro interaction assay, based on the AlphaLISA technology, to monitor the integrase-GCN2 interaction. From an initial library of 133 FDA-approved molecules, we identified nine compounds that either inhibited or stimulated the interaction between GCN2 and HIV integrase. In vitro characterization of these nine hits validated this pilot screen and demonstrated that the GCN2-integrase interaction could be a viable solution for targeting integrase out of its active site.
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Chen L, Keppler OT, Schölz C. Post-translational Modification-Based Regulation of HIV Replication. Front Microbiol 2018; 9:2131. [PMID: 30254620 PMCID: PMC6141784 DOI: 10.3389/fmicb.2018.02131] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 08/20/2018] [Indexed: 12/13/2022] Open
Abstract
Human immunodeficiency virus (HIV) relies heavily on the host cellular machinery for production of viral progeny. To exploit cellular proteins for replication and to overcome host factors with antiviral activity, HIV has evolved a set of regulatory and accessory proteins to shape an optimized environment for its replication and to facilitate evasion from the immune system. Several cellular pathways are hijacked by the virus to modulate critical steps during the viral life cycle. Thereby, post-translational modifications (PTMs) of viral and cellular proteins gain increasingly attention as modifying enzymes regulate virtually every step of the viral replication cycle. This review summarizes the current knowledge of HIV-host interactions influenced by PTMs with a special focus on acetylation, ubiquitination, and phosphorylation of proteins linked to cellular signaling and viral replication. Insights into these interactions are surmised to aid development of new intervention strategies.
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Affiliation(s)
- Lin Chen
- Max von Pettenkofer-Institute and Gene Center, Virology, National Reference Center for Retroviruses, Faculty of Medicine, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Oliver T Keppler
- Max von Pettenkofer-Institute and Gene Center, Virology, National Reference Center for Retroviruses, Faculty of Medicine, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Christian Schölz
- Max von Pettenkofer-Institute and Gene Center, Virology, National Reference Center for Retroviruses, Faculty of Medicine, Ludwig-Maximilians-University Munich, Munich, Germany
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GCN2 phosphorylates HIV-1 integrase and decreases HIV-1 replication by limiting viral integration. Sci Rep 2017; 7:2283. [PMID: 28536474 PMCID: PMC5442153 DOI: 10.1038/s41598-017-02276-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 04/10/2017] [Indexed: 12/22/2022] Open
Abstract
GCN2 is a serine/threonine kinase involved in cellular stress response related to amino acid starvation. Previously, we showed that GCN2 interacts with HIV-1 integrase and is activated during HIV-1 infection. Herein, we identified HIV-1 integrase as a previously unknown substrate of GCN2 in vitro with a major site of phosphorylation at residue S255 located in the C-terminal domain of HIV-1 integrase. The underlying mechanism was investigated and it appeared that the integrase active site was required in order for GCN2 to target the integrase residue S255. Moreover, various integrases from other retroviruses (e.g. MLV, ASV) were also recognized as a substrate by GCN2. In cells, HIV-1 lentiviral particles harboring mutation at integrase position 255 were affected in their replication. Preventing phosphorylation resulted in an increase in infectivity that correlated with an increase in viral DNA integration. Infectivity of MLV was also higher in cells knocked-out for GCN2 suggesting a conserved mechanism to control viral replication. Altogether, our data suggest that GCN2 may constitute a general guardian of genome stability by regulating foreign DNA integration and as such be part of the antiviral armamentarium of the cell.
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12
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HIV Exploits Antiviral Host Innate GCN2-ATF4 Signaling for Establishing Viral Replication Early in Infection. mBio 2017; 8:mBio.01518-16. [PMID: 28465428 PMCID: PMC5414007 DOI: 10.1128/mbio.01518-16] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Antiviral innate host defenses against acute viral infections include suppression of host protein synthesis to restrict viral protein production. Less is known about mechanisms by which viral pathogens subvert host antiviral innate responses for establishing their replication and dissemination. We investigated early innate defense against human immunodeficiency virus (HIV) infection and viral evasion by utilizing human CD4+ T cell cultures in vitro and a simian immunodeficiency virus (SIV) model of AIDS in vivo. Our data showed that early host innate defense against the viral infection involves GCN2-ATF4 signaling-mediated suppression of global protein synthesis, which is exploited by the virus for supporting its own replication during early viral infection and dissemination in the gut mucosa. Suppression of protein synthesis and induction of protein kinase GCN2-ATF4 signaling were detected in the gut during acute SIV infection. These changes diminished during chronic viral infection. HIV replication induced by serum deprivation in CD4+ T cells was linked to the induction of ATF4 that was recruited to the HIV long terminal repeat (LTR) to promote viral transcription. Experimental inhibition of GCN2-ATF4 signaling either by a specific inhibitor or by amino acid supplementation suppressed the induction of HIV expression. Enhancing ATF4 expression through selenium administration resulted in reactivation of latent HIV in vitro as well as ex vivo in the primary CD4+ T cells isolated from patients receiving suppressive antiretroviral therapy (ART). In summary, HIV/SIV exploits the early host antiviral response through GCN2-ATF4 signaling by utilizing ATF4 for activating the viral LTR transcription to establish initial viral replication and is a potential target for HIV prevention and therapy. Understanding how HIV overcomes host antiviral innate defense response in order to establish infection and dissemination is critical for developing prevention and treatment strategies. Most investigations focused on the viral pathogenic mechanisms leading to immune dysfunction following robust viral infection and dissemination. Less is known about mechanisms that enable HIV to establish its presence despite rapid onset of host antiviral innate response. Our novel findings provide insights into the viral strategy that hijacks the host innate response of the suppression of protein biosynthesis to restrict the virus production. The virus leverages transcription factor ATF4 expression during the GCN2-ATF4 signaling response and utilizes it to activate viral transcription through the LTR to support viral transcription and production in both HIV and SIV infections. This unique viral strategy is exploiting the innate response and is distinct from the mechanisms of immune dysfunction after the critical mass of viral loads is generated.
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Fung TS, Huang M, Liu DX. Coronavirus-induced ER stress response and its involvement in regulation of coronavirus-host interactions. Virus Res 2014; 194:110-23. [PMID: 25304691 PMCID: PMC7114476 DOI: 10.1016/j.virusres.2014.09.016] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 09/25/2014] [Accepted: 09/28/2014] [Indexed: 12/11/2022]
Abstract
Coronavirus replication is structurally and functionally associated with the endoplasmic reticulum (ER), a major site of protein synthesis, folding, modification and sorting in the eukaryotic cells. Disturbance of ER homeostasis may occur under various physiological or pathological conditions. In response to the ER stress, signaling pathways of the unfolded protein response (UPR) are activated. UPR is mediated by three ER transmembrane sensors, namely the PKR-like ER protein kinase (PERK), the inositol-requiring protein 1 (IRE1) and the activating transcriptional factor 6 (ATF6). UPR facilitates adaptation to ER stress by reversible translation attenuation, enhancement of ER protein folding capacity and activation of ER-associated degradation (ERAD). In cells under prolonged and irremediable ER stress, UPR can also trigger apoptotic cell death. Accumulating evidence has shown that coronavirus infection causes ER stress and induces UPR in the infected cells. UPR is closely associated with a number of major signaling pathways, including autophagy, apoptosis, the mitogen-activated protein (MAP) kinase pathways, innate immunity and pro-inflammatory response. Therefore, studies on the UPR are pivotal in elucidating the complicated issue of coronavirus-host interaction. In this paper, we present the up-to-date knowledge on coronavirus-induced UPR and discuss its potential involvement in regulation of innate immunity and apoptosis.
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Affiliation(s)
- To Sing Fung
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
| | - Mei Huang
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
| | - Ding Xiang Liu
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551.
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Burugu S, Daher A, Meurs EF, Gatignol A. HIV-1 translation and its regulation by cellular factors PKR and PACT. Virus Res 2014; 193:65-77. [PMID: 25064266 DOI: 10.1016/j.virusres.2014.07.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 07/13/2014] [Accepted: 07/14/2014] [Indexed: 12/24/2022]
Abstract
The synthesis of proteins from viral mRNA is the first step towards viral assembly. Viruses are dependent upon the cellular translation machinery to synthesize their own proteins. The synthesis of proteins from the human immunodeficiency virus (HIV) type 1 and 2 RNAs utilize several alternative mechanisms. The regulation of viral protein production requires a constant interplay between viral requirements and the cell response to viral infection. Among the antiviral cell responses, the interferon-induced RNA activated protein kinase, PKR, regulates the cellular and viral translation. During HIV-1 infection, PKR activation is highly regulated by viral and cellular factors. The cellular TAR RNA Binding Protein, TRBP, the Adenosine Deaminase acting on RNA, ADAR1, and the PKR Activator, PACT, play important roles. Recent data show that PACT changes its function from activator to inhibitor in HIV-1 infected cells. Therefore, HIV-1 has evolved to replicate in cells in which TRBP, ADAR1 and PACT prevent PKR activation to allow efficient viral protein synthesis. This proper translation will initiate the assembly of viral particles.
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Affiliation(s)
- Samantha Burugu
- Virus-cell Interactions Laboratory, Lady Davis Institute for Medical Research, Montréal, QC, Canada; Department of Microbiology and Immunology, McGill University, Montréal, QC, Canada
| | - Aïcha Daher
- Virus-cell Interactions Laboratory, Lady Davis Institute for Medical Research, Montréal, QC, Canada
| | - Eliane F Meurs
- Institut Pasteur, Department of Virology, Hepacivirus and Innate Immunity Unit, Paris, France
| | - Anne Gatignol
- Virus-cell Interactions Laboratory, Lady Davis Institute for Medical Research, Montréal, QC, Canada; Department of Microbiology and Immunology, McGill University, Montréal, QC, Canada; Department of Medicine, Division of Experimental Medicine, McGill University, Montréal, QC, Canada.
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