1
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BenDavid E, Yang C, Zhou Y, Pfaller CK, Samuel CE, Ma D. Host WD repeat-containing protein 5 inhibits protein kinase R-mediated integrated stress response during measles virus infection. J Virol 2024; 98:e0102024. [PMID: 39194235 PMCID: PMC11406981 DOI: 10.1128/jvi.01020-24] [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: 06/10/2024] [Accepted: 07/09/2024] [Indexed: 08/29/2024] Open
Abstract
Some negative-sense RNA viruses, including measles virus (MeV), share the characteristic that during their infection cycle, cytoplasmic inclusion bodies (IBs) are formed where components of the viral replication machinery are concentrated. As a foci of viral replication, how IBs act to enhance the efficiency of infection by affecting virus-host interactions remains an important topic of investigation. We previously established that upon MeV infection, the epigenetic host protein, WD repeat-containing protein 5 (WDR5), translocates to cytoplasmic viral IBs and facilitates MeV replication. We now show that WDR5 is recruited to IBs by forming a complex with IB-associated MeV phosphoprotein via a conserved binding motif located on the surface of WDR5. Furthermore, we provide evidence that WDR5 promotes viral replication by suppressing a major innate immune response pathway, the double-stranded RNA-mediated activation of protein kinase R and integrated stress response. IMPORTANCE MeV is a pathogen that remains a global concern, with an estimated 9 million measles cases and 128,000 measles deaths in 2022 according to the World Health Organization. A large population of the world still has inadequate access to the effective vaccine against the exceptionally transmissible MeV. Measles disease is characterized by a high morbidity in children and in immunocompromised individuals. An important area of research for negative-sense RNA viruses, including MeV, is the characterization of the complex interactome between virus and host occurring at cytoplasmic IBs where viral replication occurs. Despite the progress made in understanding IB structures, little is known regarding the virus-host interactions within IBs and the role of these interactions in promoting viral replication and antagonizing host innate immunity. Herein we provide evidence suggesting a model by which MeV IBs utilize the host protein WDR5 to suppress the protein kinase R-integrated stress response pathway.
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Affiliation(s)
- Ethan BenDavid
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California, USA
| | - Chuyuan Yang
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California, USA
| | - Yuqin Zhou
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California, USA
| | - Christian K Pfaller
- Division of Veterinary Medicine, Paul-Ehrlich-Institute, Langen, Germany
- Department of Molecular Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Charles E Samuel
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California, USA
- Neuroscience Research Institute, University of California, Santa Barbara, California, USA
| | - Dzwokai Ma
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California, USA
- Neuroscience Research Institute, University of California, Santa Barbara, California, USA
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2
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Altintas O, MacArthur MR. General control nonderepressible 2 (GCN2) as a therapeutic target in age-related diseases. FRONTIERS IN AGING 2024; 5:1447370. [PMID: 39319345 PMCID: PMC11420162 DOI: 10.3389/fragi.2024.1447370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2024] [Accepted: 08/28/2024] [Indexed: 09/26/2024]
Abstract
The function of General Control Nonderepressible 2 (GCN2), an evolutionary-conserved component of the integrated stress response (ISR), has been well-documented across organisms from yeast to mammals. Recently GCN2 has also gained attention for its role in health and disease states. In this review, we provide a brief overview of GCN2, including its structure, activation mechanisms and interacting partners, and explore its potential significance as a therapeutic target in various age-related diseases including neurodegeneration, inflammatory disorders and cancer. Finally, we summarize the barriers to effectively targeting GCN2 for the treatment of disease and to promote a healthier aging process.
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Affiliation(s)
- Ozlem Altintas
- Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
| | - Michael R. MacArthur
- Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, United States
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3
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Chaumont L, Peruzzi M, Huetz F, Raffy C, Le Hir J, Minke J, Boudinot P, Collet B. Salmonid Double-stranded RNA-Dependent Protein Kinase Activates Apoptosis and Inhibits Protein Synthesis. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2024; 213:700-717. [PMID: 39058317 DOI: 10.4049/jimmunol.2400076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Accepted: 06/30/2024] [Indexed: 07/28/2024]
Abstract
dsRNA-dependent protein kinase R (PKR) is a key factor of innate immunity. It is involved in translation inhibition, apoptosis, and enhancement of the proinflammatory and IFN responses. However, how these antiviral functions are conserved during evolution remains largely unknown. Overexpression and knockout studies in a Chinook salmon (Oncorhynchus tshawytscha) cell line were conducted to assess the role of salmonid PKR in the antiviral response. Three distinct mRNA isoforms from a unique pkr gene, named pkr-fl (full length), pkr-ml (medium length) and pkr-sl (short length), were cloned and a pkr-/- clonal fish cell line was developed using CRISPR/Cas9 genome editing. PKR-FL includes an N-terminal dsRNA-binding domain and a C-terminal kinase domain, whereas PKR-ML and PKR-SL display a truncated or absent kinase domain, respectively. PKR-FL is induced during IFNA2 stimulation but not during viral hemorrhagic septicemia virus (VHSV) infection. Overexpression experiments showed that only PKR-FL possesses antiviral functions, including activation of apoptosis and inhibition of de novo protein synthesis. Knockout experiments confirmed that PKR is involved in apoptosis activation during the late stage of VHSV infection. Endogenous PKR also plays a critical role in translation inhibition upon poly(I:C) transfection after IFNA2 treatment. It is, however, not involved in translational arrest during VHSV infection. Extra- and intracellular titrations showed that endogenous PKR does not directly inhibit viral replication but apparently favors virion release into the supernatant, likely by triggering late apoptosis. Altogether, our data confirm that salmonid PKR has conserved molecular functions that VHSV appears to bypass with subversion strategies.
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Affiliation(s)
- Lise Chaumont
- Université Paris-Saclay, INRAE, UVSQ, VIM, Jouy-en-Josas, France
| | - Mathilde Peruzzi
- Université Paris-Saclay, INRAE, UVSQ, VIM, Jouy-en-Josas, France
| | - François Huetz
- Unit of Antibodies in Therapy and Pathology, UMR 1222 INSERM, Institut Pasteur, Paris, France
| | | | | | | | - Pierre Boudinot
- Université Paris-Saclay, INRAE, UVSQ, VIM, Jouy-en-Josas, France
| | - Bertrand Collet
- Université Paris-Saclay, INRAE, UVSQ, VIM, Jouy-en-Josas, France
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4
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Bou-Nader C, Gaikwad S, Bahmanjah S, Zhang F, Hinnebusch AG, Zhang J. Gcn2 structurally mimics and functionally repurposes the HisRS enzyme for the integrated stress response. Proc Natl Acad Sci U S A 2024; 121:e2409628121. [PMID: 39163341 PMCID: PMC11363354 DOI: 10.1073/pnas.2409628121] [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: 05/14/2024] [Accepted: 07/22/2024] [Indexed: 08/22/2024] Open
Abstract
Protein kinase Gcn2 attenuates protein synthesis in response to amino acid starvation while stimulating translation of a transcriptional activator of amino acid biosynthesis. Gcn2 activation requires a domain related to histidyl-tRNA synthetase (HisRS), the enzyme that aminoacylates tRNAHis. While evidence suggests that deacylated tRNA binds the HisRS domain for kinase activation, ribosomal P-stalk proteins have been implicated as alternative activating ligands on stalled ribosomes. We report crystal structures of the HisRS domain of Chaetomium thermophilum Gcn2 that reveal structural mimicry of both catalytic (CD) and anticodon-binding (ABD) domains, which in authentic HisRS bind the acceptor stem and anticodon loop of tRNAHis. Elements for forming histidyl adenylate and aminoacylation are lacking, suggesting that Gcn2HisRS was repurposed for kinase activation, consistent with mutations in the CD that dysregulate yeast Gcn2 function. Substituting conserved ABD residues well positioned to contact the anticodon loop or that form a conserved ABD-CD interface impairs Gcn2 function in starved cells. Mimicry in Gcn2HisRS of two highly conserved structural domains for binding both ends of tRNA-each crucial for Gcn2 function-supports that deacylated tRNAs activate Gcn2 and exemplifies how a metabolic enzyme is repurposed to host new local structures and sequences that confer a novel regulatory function.
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Affiliation(s)
- Charles Bou-Nader
- Laboratory of Molecular Biology, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD20892
| | - Swati Gaikwad
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD20892
| | - Soheila Bahmanjah
- Laboratory of Molecular Biology, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD20892
| | - Fan Zhang
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD20892
| | - Alan G. Hinnebusch
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD20892
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD20892
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5
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Darawshi O, Yassin O, Shmuel M, Wek RC, Mahdizadeh SJ, Eriksson LA, Hatzoglou M, Tirosh B. Phosphorylation of GCN2 by mTOR confers adaptation to conditions of hyper-mTOR activation under stress. J Biol Chem 2024; 300:107575. [PMID: 39013537 PMCID: PMC11362803 DOI: 10.1016/j.jbc.2024.107575] [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: 02/03/2024] [Revised: 07/02/2024] [Accepted: 07/05/2024] [Indexed: 07/18/2024] Open
Abstract
Adaptation to the shortage in free amino acids (AA) is mediated by 2 pathways, the integrated stress response (ISR) and the mechanistic target of rapamycin (mTOR). In response to reduced levels, primarily of leucine or arginine, mTOR in its complex 1 configuration (mTORC1) is suppressed leading to a decrease in translation initiation and elongation. The eIF2α kinase general control nonderepressible 2 (GCN2) is activated by uncharged tRNAs, leading to induction of the ISR in response to a broader range of AA shortage. ISR confers a reduced translation initiation, while promoting the selective synthesis of stress proteins, such as ATF4. To efficiently adapt to AA starvation, the 2 pathways are cross-regulated at multiple levels. Here we identified a new mechanism of ISR/mTORC1 crosstalk that optimizes survival under AA starvation, when mTORC1 is forced to remain active. mTORC1 activation during acute AA shortage, augmented ATF4 expression in a GCN2-dependent manner. Under these conditions, enhanced GCN2 activity was not dependent on tRNA sensing, inferring a different activation mechanism. We identified a labile physical interaction between GCN2 and mTOR that results in a phosphorylation of GCN2 on serine 230 by mTOR, which promotes GCN2 activity. When examined under prolonged AA starvation, GCN2 phosphorylation by mTOR promoted survival. Our data unveils an adaptive mechanism to AA starvation, when mTORC1 evades inhibition.
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Affiliation(s)
- Odai Darawshi
- The School of Pharmacy, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Olaya Yassin
- The School of Pharmacy, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Miri Shmuel
- The School of Pharmacy, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Ronald C Wek
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - S Jalil Mahdizadeh
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Leif A Eriksson
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Maria Hatzoglou
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, Ohio, USA
| | - Boaz Tirosh
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio, USA.
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6
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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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7
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Prabhakar A, Kumar R, Wadhwa M, Ghatpande P, Zhang J, Zhao Z, Lizama CO, Kharbikar BN, Gräf S, Treacy CM, Morrell NW, Graham BB, Lagna G, Hata A. Reversal of pulmonary veno-occlusive disease phenotypes by inhibition of the integrated stress response. NATURE CARDIOVASCULAR RESEARCH 2024; 3:799-818. [PMID: 39196173 PMCID: PMC11409862 DOI: 10.1038/s44161-024-00495-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 05/29/2024] [Indexed: 08/29/2024]
Abstract
Pulmonary veno-occlusive disease (PVOD) is a rare form of pulmonary hypertension arising from EIF2AK4 gene mutations or mitomycin C (MMC) administration. The lack of effective PVOD therapies is compounded by a limited understanding of the mechanisms driving vascular remodeling in PVOD. Here we show that administration of MMC in rats mediates activation of protein kinase R (PKR) and the integrated stress response (ISR), which leads to the release of the endothelial adhesion molecule vascular endothelial (VE) cadherin (VE-Cad) in complex with RAD51 to the circulation, disruption of endothelial barrier and vascular remodeling. Pharmacological inhibition of PKR or ISR attenuates VE-Cad depletion, elevation of vascular permeability and vascular remodeling instigated by MMC, suggesting potential clinical intervention for PVOD. Finally, the severity of PVOD phenotypes was increased by a heterozygous BMPR2 mutation that truncates the carboxyl tail of the receptor BMPR2, underscoring the role of deregulated bone morphogenetic protein signaling in the development of PVOD.
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Grants
- R01HL132058 U.S. Department of Health & Human Services | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- R01HL135872 U.S. Department of Health & Human Services | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- RG/19/3/34265 British Heart Foundation (BHF)
- R01HL164581 U.S. Department of Health & Human Services | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- R01 HL153915 NHLBI NIH HHS
- R01HL153915 U.S. Department of Health & Human Services | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- 28IR-0047 Tobacco-Related Disease Research Program (TRDRP)
- R01 HL135872 NHLBI NIH HHS
- 19CDA34730030 American Heart Association (American Heart Association, Inc.)
- R24 HL123767 NHLBI NIH HHS
- P01HL152961 U.S. Department of Health & Human Services | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- R01 HL164581 NHLBI NIH HHS
- P01 HL152961 NHLBI NIH HHS
- R01 HL132058 NHLBI NIH HHS
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Affiliation(s)
- Amit Prabhakar
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, USA
| | - Rahul Kumar
- Lung Biology Center, Pulmonary and Critical Care Medicine, Zuckerberg San Francisco General Hospital, San Francisco, CA, USA
| | - Meetu Wadhwa
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco, CA, USA
| | - Prajakta Ghatpande
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, USA
| | - Jingkun Zhang
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, USA
| | - Ziwen Zhao
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, USA
| | - Carlos O Lizama
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, USA
| | - Bhushan N Kharbikar
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA
| | - Stefan Gräf
- Department of Medicine, University of Cambridge, Cambridge, UK
| | - Carmen M Treacy
- Department of Medicine, University of Cambridge, Cambridge, UK
| | | | - Brian B Graham
- Lung Biology Center, Pulmonary and Critical Care Medicine, Zuckerberg San Francisco General Hospital, San Francisco, CA, USA
| | - Giorgio Lagna
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, USA
| | - Akiko Hata
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, USA.
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA.
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8
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Sarkar S, Ganguly S, Ganguly NK, Sarkar DP, Sharma NR. Chandipura Virus Forms Cytoplasmic Inclusion Bodies through Phase Separation and Proviral Association of Cellular Protein Kinase R and Stress Granule Protein TIA-1. Viruses 2024; 16:1027. [PMID: 39066190 PMCID: PMC11281494 DOI: 10.3390/v16071027] [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: 04/18/2024] [Revised: 06/01/2024] [Accepted: 06/07/2024] [Indexed: 07/28/2024] Open
Abstract
Negative-strand RNA viruses form cytoplasmic inclusion bodies (IBs) representing virus replication foci through phase separation or biomolecular condensation of viral and cellular proteins, as a hallmark of their infection. Alternatively, mammalian cells form stalled mRNA containing antiviral stress granules (SGs), as a consequence of phosphorylation of eukaryotic initiation factor 2α (eIF2α) through condensation of several RNA-binding proteins including TIA-1. Whether and how Chandipura virus (CHPV), an emerging human pathogen causing influenza-like illness, coma and death, forms IBs and evades antiviral SGs remain unknown. By confocal imaging on CHPV-infected Vero-E6 cells, we found that CHPV infection does not induce formation of distinct canonical SGs. Instead, CHPV proteins condense and co-localize together with SG proteins to form heterogeneous IBs, which ensued independent of the activation of eIF2α and eIF2α kinase, protein kinase R (PKR). Interestingly, siRNA-mediated depletion of PKR or TIA-1 significantly decreased viral transcription and virion production. Moreover, CHPV infection also caused condensation and recruitment of PKR to IBs. Compared to SGs, IBs exhibited significant rapidity in disassembly dynamics. Altogether, our study demonstrating that CHPV replication co-optimizes with SG proteins and revealing an unprecedented proviral role of TIA-1/PKR may have implications in understanding the mechanisms regulating CHPV-IB formation and designing antiviral therapeutics. Importance: CHPV is an emerging tropical pathogen reported to cause acute influenza-like illness and encephalitis in children with a very high mortality rate of ~70%. Lack of vaccines and an effective therapy against CHPV makes it a potent pathogen for causing an epidemic in tropical parts of globe. Given these forewarnings, it is of paramount importance that CHPV biology must be understood comprehensively. Targeting of host factors offers several advantages over targeting the viral components due to the generally higher mutation rate in the viral genome. In this study, we aimed at understanding the role of SGs forming cellular RNA-binding proteins in CHPV replication. Our study helps understand participation of cellular factors in CHPV replication and could help develop effective therapeutics against the virus.
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Affiliation(s)
- Sharmistha Sarkar
- Department of Molecular Medicine, School of Interdisciplinary Studies, Jamia Hamdard University, Hamdard Nagar, New Delhi 110062, India; (S.S.); (S.G.)
| | - Surajit Ganguly
- Department of Molecular Medicine, School of Interdisciplinary Studies, Jamia Hamdard University, Hamdard Nagar, New Delhi 110062, India; (S.S.); (S.G.)
| | - Nirmal K. Ganguly
- Department of Education and Research, AERF, Artemis Hospitals, Gurugram 122001, India;
| | - Debi P. Sarkar
- Department of Biochemistry, University of Delhi South Campus, New Delhi 110021, India
| | - Nishi Raj Sharma
- Department of Molecular Medicine, School of Interdisciplinary Studies, Jamia Hamdard University, Hamdard Nagar, New Delhi 110062, India; (S.S.); (S.G.)
- Department of Education and Research, AERF, Artemis Hospitals, Gurugram 122001, India;
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9
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Zheng X, Shen J, Jiang H, Tian M, Wang Q, Guo K, Chen R, Xia Q, Yan Q, Du L, Duan S. Exploring the multifaceted role of GCN1: Implications in cellular responses and disease pathogenesis. Biomed Pharmacother 2024; 175:116681. [PMID: 38705128 DOI: 10.1016/j.biopha.2024.116681] [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: 02/04/2024] [Revised: 04/21/2024] [Accepted: 04/29/2024] [Indexed: 05/07/2024] Open
Abstract
GCN1 is a highly conserved protein present widely across eukaryotes. As an upstream activator of protein kinase GCN2, GCN1 plays a pivotal role in integrated stress responses, such as amino acid starvation and oxidative stress. Through interaction with GCN2, GCN1 facilitates the activation of GCN2, thus initiating downstream signaling cascades in response to cellular stressors. In these contexts, the activation of GCN2 necessitates the presence and action of GCN1. Notably, GCN1 also operates as a ribosome collision sensor, contributing significantly to the translation quality control pathway. These discoveries offer valuable insights into cellular responses to internal stresses, vital for maintaining cellular homeostasis. Additionally, GCN1 exhibits the ability to regulate the cell cycle and suppress inflammation, among other processes, independently of GCN2. Our review outlines the structural characteristics and biological functions of GCN1, shedding light on its significant involvement in the onset and progression of various cancer and non-cancer diseases. Our work underscores the role of GCN1 in the context of drug therapeutic effects, hinting at its potential as a promising drug target. Furthermore, our work delves deep into the functional mechanisms of GCN1, promising innovative avenues for the diagnosis and treatment of diseases in the future. The exploration of GCN1's multifaceted roles not only enhances our understanding of its mechanisms but also paves the way for novel therapeutic interventions. The ongoing quest to unveil additional functions of GCN1 holds the promise of further enriching our comprehension of its mode of action.
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Affiliation(s)
- Xinying Zheng
- College of Pharmacy, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, China; Key Laboratory of Novel Targets and Drug Study for Neural Repair of Zhejiang Province, School of Medicine, Hangzhou City University, Hangzhou, Zhejiang 310015, China
| | - Jinze Shen
- Key Laboratory of Novel Targets and Drug Study for Neural Repair of Zhejiang Province, School of Medicine, Hangzhou City University, Hangzhou, Zhejiang 310015, China
| | - Hongting Jiang
- Key Laboratory of Novel Targets and Drug Study for Neural Repair of Zhejiang Province, School of Medicine, Hangzhou City University, Hangzhou, Zhejiang 310015, China
| | - Mei Tian
- College of Pharmacy, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, China; Key Laboratory of Novel Targets and Drug Study for Neural Repair of Zhejiang Province, School of Medicine, Hangzhou City University, Hangzhou, Zhejiang 310015, China; Geriatric Medicine Center, Department of Endocrinology, Zhejiang Provincial People's Hospital (Affiliated People's Hospital), Hangzhou Medical College, Hangzhou, Zhejiang 310014, China
| | - Qurui Wang
- Key Laboratory of Novel Targets and Drug Study for Neural Repair of Zhejiang Province, School of Medicine, Hangzhou City University, Hangzhou, Zhejiang 310015, China
| | - Kailin Guo
- Key Laboratory of Novel Targets and Drug Study for Neural Repair of Zhejiang Province, School of Medicine, Hangzhou City University, Hangzhou, Zhejiang 310015, China
| | - Ruixiu Chen
- Key Laboratory of Novel Targets and Drug Study for Neural Repair of Zhejiang Province, School of Medicine, Hangzhou City University, Hangzhou, Zhejiang 310015, China
| | - Qing Xia
- College of Pharmacy, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, China; Key Laboratory of Novel Targets and Drug Study for Neural Repair of Zhejiang Province, School of Medicine, Hangzhou City University, Hangzhou, Zhejiang 310015, China
| | - Qibin Yan
- College of Pharmacy, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, China; Key Laboratory of Novel Targets and Drug Study for Neural Repair of Zhejiang Province, School of Medicine, Hangzhou City University, Hangzhou, Zhejiang 310015, China
| | - Lihua Du
- College of Pharmacy, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, China
| | - Shiwei Duan
- Key Laboratory of Novel Targets and Drug Study for Neural Repair of Zhejiang Province, School of Medicine, Hangzhou City University, Hangzhou, Zhejiang 310015, China.
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10
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Zhang R, Karijolich J. RNA recognition by PKR during DNA virus infection. J Med Virol 2024; 96:e29424. [PMID: 38285432 PMCID: PMC10832991 DOI: 10.1002/jmv.29424] [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: 12/03/2023] [Revised: 01/10/2024] [Accepted: 01/11/2024] [Indexed: 01/30/2024]
Abstract
Protein kinase R (PKR) is a double-stranded RNA (dsRNA) binding protein that plays a crucial role in innate immunity during viral infection and can restrict both DNA and RNA viruses. The potency of its antiviral function is further reflected by the large number of viral-encoded PKR antagonists. However, much about the regulation of dsRNA accumulation and PKR activation during viral infection remains unknown. Since DNA viruses do not have an RNA genome or RNA replication intermediates like RNA viruses do, PKR-mediated dsRNA detection in the context of DNA virus infection is particularly intriguing. Here, we review the current state of knowledge regarding the regulation of PKR activation and its antagonism during infection with DNA viruses.
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Affiliation(s)
- Ruilin Zhang
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232-2363, USA
- Vanderbilt Institute for Infection, Immunology and Inflammation, Vanderbilt Center for Immunobiology, Nashville. Nashville, TN 37232-2363, USA
| | - John Karijolich
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232-2363, USA
- Vanderbilt Institute for Infection, Immunology and Inflammation, Vanderbilt Center for Immunobiology, Nashville. Nashville, TN 37232-2363, USA
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11
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Prabhakar A, Kumar R, Wadhwa M, Ghatpande P, Zhang J, Zhao Z, Lizama CO, Kharbikar BN, Gräf S, Treacy CM, Morrell NW, Graham BB, Lagna G, Hata A. Reversal of pulmonary veno-occlusive disease phenotypes by inhibition of the integrated stress response. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.27.568924. [PMID: 38076809 PMCID: PMC10705277 DOI: 10.1101/2023.11.27.568924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/15/2024]
Abstract
Pulmonary veno-occlusive disease (PVOD) is a rare form of pulmonary hypertension arising from EIF2AK4 gene mutations or mitomycin C (MMC) administration. The lack of effective PVOD therapies is compounded by a limited understanding of the mechanisms driving the vascular remodeling in PVOD. We show that the administration of MMC in rats mediates the activation of protein kinase R (PKR) and the integrated stress response (ISR), which lead to the release of the endothelial adhesion molecule VE-Cadherin in the complex with Rad51 to the circulation, disruption of endothelial barrier, and vascular remodeling. Pharmacological inhibition of PKR or ISR attenuates the depletion of VE-Cadherin, elevation of vascular permeability, and vascular remodeling instigated by MMC, suggesting potential clinical intervention for PVOD. Finally, the severity of PVOD phenotypes was increased by a heterozygous BMPR2 mutation that truncates the carboxyl tail of BMPR2, underscoring the role of deregulated BMP signal in the development of PVOD.
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12
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Carlson KR, Georgiadis MM, Tameire F, Staschke KA, Wek RC. Activation of Gcn2 by small molecules designed to be inhibitors. J Biol Chem 2023; 299:104595. [PMID: 36898579 PMCID: PMC10124904 DOI: 10.1016/j.jbc.2023.104595] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 03/06/2023] [Indexed: 03/10/2023] Open
Abstract
The integrated stress response (ISR) is an important mechanism by which cells confer protection against environmental stresses. Central to the ISR is a collection of related protein kinases that monitor stress conditions, such as Gcn2 (EIF2AK4) that recognizes nutrient limitations, inducing phosphorylation of eukaryotic translation initiation factor 2 (eIF2). Gcn2 phosphorylation of eIF2 lowers bulk protein synthesis, conserving energy and nutrients, coincident with preferential translation of stress-adaptive gene transcripts, such as that encoding the Atf4 transcriptional regulator. While Gcn2 is central for cell protection to nutrient stress and its depletion in humans leads to pulmonary disorders, Gcn2 can also contribute to the progression of cancers and facilitate neurological disorders during chronic stress. Consequently, specific ATP-competitive inhibitors of Gcn2 protein kinase have been developed. In this study, we report that one such Gcn2 inhibitor, Gcn2iB, can activate Gcn2, and we probe the mechanism by which this activation occurs. Low concentrations of Gcn2iB increase Gcn2 phosphorylation of eIF2 and enhance Atf4 expression and activity. Of importance, Gcn2iB can activate Gcn2 mutants devoid of functional regulatory domains or with certain kinase domain substitutions derived from Gcn2-deficient human patients. Other ATP-competitive inhibitors can also activate Gcn2, although there are differences in their mechanisms of activation. These results provide a cautionary note about the pharmacodynamics of eIF2 kinase inhibitors in therapeutic applications. Compounds designed to be kinase inhibitors that instead directly activate Gcn2, even loss of function variants, may provide tools to alleviate deficiencies in Gcn2 and other regulators of the ISR.
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Affiliation(s)
- Kenneth R Carlson
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Millie M Georgiadis
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA; Indiana University Melvin and Bren Simon Comprehensive Cancer Center, Indianapolis, Indiana, USA
| | | | - Kirk A Staschke
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA; Indiana University Melvin and Bren Simon Comprehensive Cancer Center, Indianapolis, Indiana, USA
| | - Ronald C Wek
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA; Indiana University Melvin and Bren Simon Comprehensive Cancer Center, Indianapolis, Indiana, USA.
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13
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BenDavid E, Pfaller CK, Pan Y, Samuel CE, Ma D. Host 5'-3' Exoribonuclease XRN1 Acts as a Proviral Factor for Measles Virus Replication by Downregulating the dsRNA-Activated Kinase PKR. J Virol 2022; 96:e0131922. [PMID: 36300942 PMCID: PMC9683022 DOI: 10.1128/jvi.01319-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 09/22/2022] [Indexed: 11/20/2022] Open
Abstract
Many negative-sense RNA viruses, including measles virus (MeV), are thought to carry out much of their viral replication in cytoplasmic membraneless foci known as inclusion bodies (IBs). The mechanisms by which IBs facilitate efficient viral replication remain largely unknown but may involve an intricate network of regulation at the host-virus interface. Viruses are able to modulate such interactions by a variety of strategies including adaptation of their genomes and "hijacking" of host proteins. The latter possibility broadens the molecular reservoir available for a virus to enhance its replication and/or antagonize host antiviral responses. Here, we show that the cellular 5'-3' exoribonuclease, XRN1, is a host protein hijacked by MeV. We found that upon MeV infection, XRN1 is translocated to cytoplasmic IBs where it acts in a proviral manner by preventing the accumulation of double-stranded RNA (dsRNA) within the IBs. This leads to the suppression of the dsRNA-induced innate immune responses mediated via the protein kinase R (PKR)-integrated stress response (ISR) pathway. IMPORTANCE Measles virus remains a major global health threat due to its high transmissibility and significant morbidity in children and immunocompromised individuals. Although there is an effective vaccine against MeV, a large population in the world remains without access to the vaccine, contributing to more than 7,000,000 measles cases and 60,000 measles deaths in 2020 (CDC). For negative-sense RNA viruses including MeV, one active research area is the exploration of virus-host interactions occurring at cytoplasmic IBs where viral replication takes place. In this study we present evidence suggesting a model in which MeV IBs antagonize host innate immunity by recruiting XRN1 to reduce dsRNA accumulation and subsequent PKR kinase activation/ISR induction. In the absence of XRN1, the increased dsRNA level acts as a potent activator of the antiviral PKR/ISR pathway leading to suppression of global cap-dependent mRNA translation and inhibition of viral replication.
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Affiliation(s)
- Ethan BenDavid
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California, USA
| | | | - Yue Pan
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California, USA
| | - Charles E. Samuel
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California, USA
- Neuroscience Research Institute, University of California, Santa Barbara, California, USA
| | - Dzwokai Ma
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California, USA
- Neuroscience Research Institute, University of California, Santa Barbara, California, USA
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14
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Brüggenthies JB, Fiore A, Russier M, Bitsina C, Brötzmann J, Kordes S, Menninger S, Wolf A, Conti E, Eickhoff JE, Murray PJ. A cell-based chemical-genetic screen for amino acid stress response inhibitors reveals torins reverse stress kinase GCN2 signaling. J Biol Chem 2022; 298:102629. [PMID: 36273589 PMCID: PMC9668732 DOI: 10.1016/j.jbc.2022.102629] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 10/07/2022] [Accepted: 10/10/2022] [Indexed: 11/06/2022] Open
Abstract
mTORC1 and GCN2 are serine/threonine kinases that control how cells adapt to amino acid availability. mTORC1 responds to amino acids to promote translation and cell growth while GCN2 senses limiting amino acids to hinder translation via eIF2α phosphorylation. GCN2 is an appealing target for cancer therapies because malignant cells can harness the GCN2 pathway to temper the rate of translation during rapid amino acid consumption. To isolate new GCN2 inhibitors, we created cell-based, amino acid limitation reporters via genetic manipulation of Ddit3 (encoding the transcription factor CHOP). CHOP is strongly induced by limiting amino acids and in this context, GCN2-dependent. Using leucine starvation as a model for essential amino acid sensing, we unexpectedly discovered ATP-competitive PI3 kinase-related kinase inhibitors, including ATR and mTOR inhibitors like torins, completely reversed GCN2 activation in a time-dependent way. Mechanistically, via inhibiting mTORC1-dependent translation, torins increased intracellular leucine, which was sufficient to reverse GCN2 activation and the downstream integrated stress response including stress-induced transcriptional factor ATF4 expression. Strikingly, we found that general translation inhibitors mirrored the effects of torins. Therefore, we propose that mTOR kinase inhibitors concurrently inhibit different branches of amino acid sensing by a dual mechanism involving direct inhibition of mTOR and indirect suppression of GCN2 that are connected by effects on the translation machinery. Collectively, our results highlight distinct ways of regulating GCN2 activity.
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Affiliation(s)
| | | | - Marion Russier
- Max Planck Institute for Biochemistry, Martinsried, Germany
| | | | | | | | | | | | - Elena Conti
- Max Planck Institute for Biochemistry, Martinsried, Germany
| | | | - Peter J. Murray
- Max Planck Institute for Biochemistry, Martinsried, Germany,For correspondence: Peter J. Murray
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15
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Marlin E, Viu-Idocin C, Arrasate M, Aragón T. The Role and Therapeutic Potential of the Integrated Stress Response in Amyotrophic Lateral Sclerosis. Int J Mol Sci 2022; 23:ijms23147823. [PMID: 35887167 PMCID: PMC9321386 DOI: 10.3390/ijms23147823] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 07/08/2022] [Accepted: 07/09/2022] [Indexed: 02/06/2023] Open
Abstract
In amyotrophic lateral sclerosis (ALS) patients, loss of cellular homeostasis within cortical and spinal cord motor neurons triggers the activation of the integrated stress response (ISR), an intracellular signaling pathway that remodels translation and promotes a gene expression program aimed at coping with stress. Beyond its neuroprotective role, under regimes of chronic or excessive stress, ISR can also promote cell/neuronal death. Given the two-edged sword nature of ISR, many experimental attempts have tried to establish the therapeutic potential of ISR enhancement or inhibition in ALS. This review discusses the complex interplay between ISR and disease progression in different models of ALS, as well as the opportunities and limitations of ISR modulation in the hard quest to find an effective therapy for ALS.
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Affiliation(s)
- Elías Marlin
- Neuroscience Program, Center for Applied Medical Research (CIMA), University of Navarra, 31008 Pamplona, Spain;
- Gene Therapy and Regulation of Gene Expression Program, Center for Applied Medical Research (CIMA), University of Navarra, 31008 Pamplona, Spain
- School of Medicine, University of Navarra, 31008 Pamplona, Spain
- Neuroscience Department, Navarra Institute for Health Research (IdiSNA), University of Navarra, 31008 Pamplona, Spain
| | | | - Montserrat Arrasate
- Neuroscience Program, Center for Applied Medical Research (CIMA), University of Navarra, 31008 Pamplona, Spain;
- School of Medicine, University of Navarra, 31008 Pamplona, Spain
- Neuroscience Department, Navarra Institute for Health Research (IdiSNA), University of Navarra, 31008 Pamplona, Spain
- Correspondence: (M.A.); (T.A.)
| | - Tomás Aragón
- Gene Therapy and Regulation of Gene Expression Program, Center for Applied Medical Research (CIMA), University of Navarra, 31008 Pamplona, Spain
- Neuroscience Department, Navarra Institute for Health Research (IdiSNA), University of Navarra, 31008 Pamplona, Spain
- Correspondence: (M.A.); (T.A.)
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16
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Zappa F, Muniozguren NL, Wilson MZ, Costello MS, Ponce-Rojas JC, Acosta-Alvear D. Signaling by the integrated stress response kinase PKR is fine-tuned by dynamic clustering. J Cell Biol 2022; 221:e202111100. [PMID: 35522180 PMCID: PMC9086502 DOI: 10.1083/jcb.202111100] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Revised: 02/15/2022] [Accepted: 04/05/2022] [Indexed: 12/16/2022] Open
Abstract
The double-stranded RNA sensor kinase PKR is one of four integrated stress response (ISR) sensor kinases that phosphorylate the α subunit of eukaryotic initiation factor 2 (eIF2α) in response to stress. The current model of PKR activation considers the formation of back-to-back PKR dimers as a prerequisite for signal propagation. Here we show that PKR signaling involves the assembly of dynamic PKR clusters. PKR clustering is driven by ligand binding to PKR's sensor domain and by front-to-front interfaces between PKR's kinase domains. PKR clusters are discrete, heterogeneous, autonomous coalescences that share some protein components with processing bodies. Strikingly, eIF2α is not recruited to PKR clusters, and PKR cluster disruption enhances eIF2α phosphorylation. Together, these results support a model in which PKR clustering may limit encounters between PKR and eIF2α to buffer downstream signaling and prevent the ISR from misfiring.
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Affiliation(s)
- Francesca Zappa
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA
| | - Nerea L. Muniozguren
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA
| | - Maxwell Z. Wilson
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA
| | - Michael S. Costello
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA
| | - Jose Carlos Ponce-Rojas
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA
| | - Diego Acosta-Alvear
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA
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17
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Dobrikov MI, Dobrikova EY, McKay ZP, Kastan JP, Brown MC, Gromeier M. PKR Binds Enterovirus IRESs, Displaces Host Translation Factors, and Impairs Viral Translation to Enable Innate Antiviral Signaling. mBio 2022; 13:e0085422. [PMID: 35652592 PMCID: PMC9239082 DOI: 10.1128/mbio.00854-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 05/16/2022] [Indexed: 12/23/2022] Open
Abstract
For RNA virus families except Picornaviridae, viral RNA sensing includes Toll-like receptors and/or RIG-I. Picornavirus RNAs, whose 5' termini are shielded by a genome-linked protein, are predominately recognized by MDA5. This has important ramifications for adaptive immunity, as MDA5-specific patterns of type-I interferon (IFN) release are optimal for CD4+T cell TH1 polarization and CD8+T cell priming. We are exploiting this principle for cancer immunotherapy with recombinant poliovirus (PV), PVSRIPO, the type 1 (Sabin) PV vaccine containing a rhinovirus type 2 internal ribosomal entry site (IRES). Here we show that PVSRIPO-elicited MDA5 signaling is preceded by early sensing of the IRES by the double-stranded (ds)RNA-activated protein kinase (PKR). PKR binding to IRES stem-loop domains 5-6 led to dimerization and autoactivation, displaced host translation initiation factors, and suppressed viral protein synthesis. Early PKR-mediated antiviral responses tempered incipient viral translation and the activity of cytopathogenic viral proteinases, setting up accentuated MDA5 innate inflammation in response to PVSRIPO infection. IMPORTANCE Among the RIG-I-like pattern recognition receptors, MDA5 stands out because it senses long dsRNA duplexes independent of their 5' features (RIG-I recognizes viral [v]RNA 5'-ppp blunt ends). Uniquely among RNA viruses, the innate defense against picornaviruses is controlled by MDA5. We show that prior to engaging MDA5, recombinant PV RNA is sensed upon PKR binding to the viral IRES at a site that overlaps with the footprint for host translation factors mediating 40S subunit recruitment. Our study demonstrates that innate antiviral type-I IFN responses orchestrated by MDA5 involve separate innate modules that recognize distinct vRNA features and interfere with viral functions at multiple levels.
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Affiliation(s)
- Mikhail I. Dobrikov
- Department of Neurosurgery, Duke University Medical School, Durham, North Carolina, USA
| | - Elena Y. Dobrikova
- Department of Neurosurgery, Duke University Medical School, Durham, North Carolina, USA
| | - Zachary P. McKay
- Department of Neurosurgery, Duke University Medical School, Durham, North Carolina, USA
| | - Jonathan P. Kastan
- Department of Neurosurgery, Duke University Medical School, Durham, North Carolina, USA
| | - Michael C. Brown
- Department of Neurosurgery, Duke University Medical School, Durham, North Carolina, USA
| | - Matthias Gromeier
- Department of Neurosurgery, Duke University Medical School, Durham, North Carolina, USA
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18
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GCN2: roles in tumour development and progression. Biochem Soc Trans 2022; 50:737-745. [PMID: 35311890 PMCID: PMC9162460 DOI: 10.1042/bst20211252] [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: 01/28/2022] [Revised: 03/01/2022] [Accepted: 03/07/2022] [Indexed: 12/12/2022]
Abstract
GCN2 (general control nonderepessible 2) is an eIF2α kinase responsible for entirely rewiring the metabolism of cells when they are put under amino acid starvation stress. Recently, there has been renewed interest in GCN2 as a potential oncotarget, with several studies reporting the development of small molecule inhibitors. The foundation of this work is built upon biochemical and cellular data which suggest GCN2 may be aberrantly overexpressed and is responsible for keeping cells on ‘life-support’ while tumours undergo significant nutritional stress during tumorigenesis, allowing cancer stem cells to develop chemotherapeutic resistance. However, most studies which have investigated the role of GCN2 in cancer have been conducted in various cancer model systems, often under a specific set of stresses, mutational backgrounds and drug cocktails. This review aims to comprehensively summarise the biochemical, molecular and cellular literature associated with GCN2 and its role in various cancers and determine whether a consensus can be developed to discern under which circumstances we may wish to target GCN2.
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19
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Yin L, Zeng Y, Zeng R, Chen Y, Wang TL, Rodabaugh KJ, Yu F, Natarajan A, Karpf AR, Dong J. Protein kinase RNA-activated controls mitotic progression and determines paclitaxel chemosensitivity through B-cell lymphoma 2 in ovarian cancer. Oncogene 2021; 40:6772-6785. [PMID: 34799660 PMCID: PMC8688329 DOI: 10.1038/s41388-021-02117-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 11/02/2021] [Accepted: 11/08/2021] [Indexed: 11/23/2022]
Abstract
Anti-tubulin agents, such as paclitaxel, have been used extensively for treatment of several types of cancer, including ovarian, lung, breast, and pancreatic cancers. Despite their wide use in cancer treatment, however, patient response is highly variable and drug resistance remains a major clinical issue. Protein kinase RNA-activated (PKR) plays a critical role in immune response to viral infection. We identified PKR as a phospho-protein in response to anti-tubulin agents and this phosphorylation occurs independent of its own kinase activity. PKR is phosphorylated by cyclin-dependent kinase 1 (CDK1) during anti-tubulin treatment and unperturbed mitosis and that PKR regulates mitotic progression in a phosphorylation-dependent manner. Furthermore, inactivation of PKR confers resistance to paclitaxel in ovarian and breast cancer cells in vitro and in vivo. PKR expression levels and activity are decreased in chemotherapeutic recurrent ovarian cancer patients. Mechanistically, our findings suggest that PKR controls paclitaxel chemosensitivity through repressing Bcl2 expression. Pharmacological inhibition of Bcl2 with FDA-approved agent venetoclax overcomes paclitaxel resistance in preclinical animal models of ovarian cancer. Our results suggest that PKR is a critical determinant of paclitaxel cytotoxicity and that PKR-Bcl2 axis as a potential therapeutic target for the treatment of recurrent drug-resistant ovarian tumors.
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Affiliation(s)
- Ling Yin
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, 68198, USA
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, 510060, China
| | - Yongji Zeng
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Renya Zeng
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Yuanhong Chen
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Tian-Li Wang
- Department of Pathology and Sydney Kimmel Comprehensive Cancer Center, Johns Hopkins Medical Institutions, Baltimore, MD, 21205, USA
| | - Kerry J Rodabaugh
- Department of Gynecologic Oncology, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Fang Yu
- Department of Biostatistics, College of Public Health, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Amarnath Natarajan
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Adam R Karpf
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Jixin Dong
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, 68198, USA.
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20
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Roth A, Gihring A, Göser F, Peifer C, Knippschild U, Bischof J. Assessing the Inhibitory Potential of Kinase Inhibitors In Vitro: Major Pitfalls and Suggestions for Improving Comparability of Data Using CK1 Inhibitors as an Example. Molecules 2021; 26:4898. [PMID: 34443486 PMCID: PMC8401859 DOI: 10.3390/molecules26164898] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 08/06/2021] [Accepted: 08/09/2021] [Indexed: 11/16/2022] Open
Abstract
Phosphorylation events catalyzed by protein kinases represent one of the most prevalent as well as important regulatory posttranslational modifications, and dysregulation of protein kinases is associated with the pathogenesis of different diseases. Therefore, interest in developing potent small molecule kinase inhibitors has increased enormously within the last two decades. A critical step in the development of new inhibitors is cell-free in vitro testing with the intention to determine comparable parameters like the commonly used IC50 value. However, values described in the literature are often biased as experimental setups used for determination of kinase activity lack comparability due to different readout parameters, insufficient normalization or the sheer number of experimental approaches. Here, we would like to hold a brief for highly sensitive, radioactive-based in vitro kinase assays especially suitable for kinases exhibiting autophosphorylation activity. Therefore, we demonstrate a systematic workflow for complementing and validating results from high-throughput screening as well as increasing the comparability of enzyme-specific inhibitor parameters for radiometric as well as non-radiometric assays. Using members of the CK1 family of serine/threonine-specific protein kinases and established CK1-specific inhibitors as examples, we clearly demonstrate the power of our proposed workflow, which has the potential to support the generation of more comparable data for biological characterization of kinase inhibitors.
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Affiliation(s)
- Aileen Roth
- Department of General and Visceral Surgery, Surgery Center, Ulm University Medical Center, Albert-Einstein-Allee 23, 89081 Ulm, Germany; (A.R.); (A.G.); (F.G.); (J.B.)
| | - Adrian Gihring
- Department of General and Visceral Surgery, Surgery Center, Ulm University Medical Center, Albert-Einstein-Allee 23, 89081 Ulm, Germany; (A.R.); (A.G.); (F.G.); (J.B.)
| | - Florian Göser
- Department of General and Visceral Surgery, Surgery Center, Ulm University Medical Center, Albert-Einstein-Allee 23, 89081 Ulm, Germany; (A.R.); (A.G.); (F.G.); (J.B.)
| | - Christian Peifer
- Institute of Pharmacy, Christian-Albrechts-University of Kiel, Gutenbergstraße 76, 24118 Kiel, Germany;
| | - Uwe Knippschild
- Department of General and Visceral Surgery, Surgery Center, Ulm University Medical Center, Albert-Einstein-Allee 23, 89081 Ulm, Germany; (A.R.); (A.G.); (F.G.); (J.B.)
| | - Joachim Bischof
- Department of General and Visceral Surgery, Surgery Center, Ulm University Medical Center, Albert-Einstein-Allee 23, 89081 Ulm, Germany; (A.R.); (A.G.); (F.G.); (J.B.)
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21
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Gao L, Chen J, Li J, Cui AQ, Zhang WW, Li XL, Wang J, Zhang XY, Zhao Y, Chen YH, Zhang C, Wang H, Xu DX. Microcystin-LR inhibits testosterone synthesis via reactive oxygen species-mediated GCN2/eIF2α pathway in mouse testes. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 781:146730. [PMID: 33798882 DOI: 10.1016/j.scitotenv.2021.146730] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 03/21/2021] [Accepted: 03/21/2021] [Indexed: 06/12/2023]
Abstract
Previous studies demonstrated that microcystin-leucine-arginine (MC-LR) disrupted testosterone (T) synthesis, but the underlying mechanisms are not entirely elucidated. This study aims to explore the role of reactive oxygen species (ROS)-mediated GCN2/eIF2α activation on MC-LR-induced disruption of testicular T synthesis. Male mice were intraperitoneally injected with MC-LR (0 or 20 μg/kg) daily for 5 weeks. Serum T was decreased in MC-LR-exposed mice (0.626 ± 0.122 vs 24.565 ± 8.486 ng/ml, P < 0.01), so did testicular T (0.667 ± 0.15 vs 8.317 ± 1.387 ng/mg protein, P < 0.01). Steroidogenic proteins including StAR, CYP11A1 and CYP17A1 were downregulated in MC-LR-exposed mouse testes and TM3 cells. Mechanistically, p-GCN2 and p-eIF2α were elevated in MC-LR-exposed TM3 cells. GCN2iB attenuated MC-LR-induced GCN2 and eIF2α phosphorylation in TM3 cells. Moreover, GCN2iB attenuated MC-LR-induced downregulation of steroidogenic proteins in TM3 cells. Further analysis found that cellular ROS were elevated and HO-1 was upregulated in MC-LR-exposed TM3 cells. PBN rescued MC-LR-induced activation of GCN2/eIF2α signaling in TM3 cells. Additionally, pretreatment with PBN attenuated MC-LR induced downregulation of steroidogenic proteins and synthases in TM3 cells. These results suggest that ROS-mediated GCN2/eIF2α activation contributes partially to MC-LR-caused downregulation of steroidogenic proteins and synthases. The present study provides a new clue for understanding the mechanism of MC-LR-induced endocrine disruption.
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Affiliation(s)
- Lan Gao
- Department of Toxicology & Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes, Anhui Medical University, Hefei 230032, China.
| | - Jing Chen
- Department of Toxicology & Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes, Anhui Medical University, Hefei 230032, China
| | - Jian Li
- Department of Toxicology & Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes, Anhui Medical University, Hefei 230032, China
| | - An-Qi Cui
- Department of Toxicology & Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes, Anhui Medical University, Hefei 230032, China
| | - Wei-Wei Zhang
- Department of Toxicology & Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes, Anhui Medical University, Hefei 230032, China
| | - Xiu-Liang Li
- Department of Toxicology & Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes, Anhui Medical University, Hefei 230032, China
| | - Jing Wang
- Department of Toxicology & Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes, Anhui Medical University, Hefei 230032, China
| | - Xiao-Yi Zhang
- Department of Toxicology & Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes, Anhui Medical University, Hefei 230032, China
| | - Ye Zhao
- Department of Nuclear Medicine, Anhui Medical University, Hefei 230032, China
| | - Yuan-Hua Chen
- Department of Toxicology & Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes, Anhui Medical University, Hefei 230032, China
| | - Cheng Zhang
- Department of Toxicology & Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes, Anhui Medical University, Hefei 230032, China
| | - Hua Wang
- Department of Toxicology & Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes, Anhui Medical University, Hefei 230032, China.
| | - De-Xiang Xu
- Department of Toxicology & Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes, Anhui Medical University, Hefei 230032, China.
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22
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López-Menchero JR, Ogawa M, Mauricio JC, Moreno J, Moreno-García J. Effect of calcium alginate coating on the cell retention and fermentation of a fungus-yeast immobilization system. Lebensm Wiss Technol 2021. [DOI: 10.1016/j.lwt.2021.111250] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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23
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Martinez NW, Gómez FE, Matus S. The Potential Role of Protein Kinase R as a Regulator of Age-Related Neurodegeneration. Front Aging Neurosci 2021; 13:638208. [PMID: 33994991 PMCID: PMC8113420 DOI: 10.3389/fnagi.2021.638208] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Accepted: 03/10/2021] [Indexed: 01/25/2023] Open
Abstract
There is a growing evidence describing a decline in adaptive homeostasis in aging-related diseases affecting the central nervous system (CNS), many of which are characterized by the appearance of non-native protein aggregates. One signaling pathway that allows cell adaptation is the integrated stress response (ISR), which senses stress stimuli through four kinases. ISR activation promotes translational arrest through the phosphorylation of the eukaryotic translation initiation factor 2 alpha (eIF2α) and the induction of a gene expression program to restore cellular homeostasis. However, depending on the stimulus, ISR can also induce cell death. One of the ISR sensors is the double-stranded RNA-dependent protein kinase [protein kinase R (PKR)], initially described as a viral infection sensor, and now a growing evidence supports a role for PKR on CNS physiology. PKR has been largely involved in the Alzheimer’s disease (AD) pathological process. Here, we reviewed the antecedents supporting the role of PKR on the efficiency of synaptic transmission and cognition. Then, we review PKR’s contribution to AD and discuss the possible participation of PKR as a player in the neurodegenerative process involved in aging-related pathologies affecting the CNS.
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Affiliation(s)
- Nicolás W Martinez
- Fundación Ciencia & Vida, Santiago, Chile.,Departamento de Ciencias Básicas, Facultad de Medicina y Ciencia, Universidad San Sebastián, Santiago, Chile.,Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile.,Center for Geroscience, Brain Health and Metabolism, Santiago, Chile
| | | | - Soledad Matus
- Fundación Ciencia & Vida, Santiago, Chile.,Departamento de Ciencias Básicas, Facultad de Medicina y Ciencia, Universidad San Sebastián, Santiago, Chile.,Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile.,Center for Geroscience, Brain Health and Metabolism, Santiago, Chile
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24
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Lum KK, Cristea IM. Host Innate Immune Response and Viral Immune Evasion During Alphaherpesvirus Infection. Curr Issues Mol Biol 2021; 42:635-686. [PMID: 33640867 DOI: 10.21775/cimb.042.635] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Both the development of the mammalian innate immune system and the antagonistic strategies acquired by alphaherpesviruses to dismantle it have been shaped by co-evolving virus-host interactions over millions of years. Here, we review mechanisms employed by mammalian cells to detect pathogen molecules, such as viral glycoproteins and nucleic acids, and induce innate immune signaling upon infection with alphaherpesviruses. We further explore strategies acquired by these viruses to bypass immune detection and activation, thereby supporting virus replication and spread. Finally, we discuss the contributions of advanced 'omics' and microscopy methods to these discoveries in immune signaling and highlight emerging technologies that can help to further our understanding of the dynamic interplay between host innate immune responses and virus immune evasion.
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Affiliation(s)
- Krystal K Lum
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544, USA
| | - Ileana M Cristea
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544, USA
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25
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Mitoxantrone triggers immunogenic prostate cancer cell death via p53-dependent PERK expression. Cell Oncol (Dordr) 2020; 43:1099-1116. [PMID: 32710433 DOI: 10.1007/s13402-020-00544-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/16/2020] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Mitoxantrone (MTX) is a synthetic compound used as a second line chemotherapeutic drug for prostate cancer. It has been reported to trigger immunogenic cell death (ICD) in animal model studies, but the underlying mechanism is not fully understood yet, especially not in prostate cancer cells. METHODS ICD was determined by assessing the release of damage-associated molecular patterns (DAMPs) in the prostate cancer-derived cell lines LNCaP, 22RV1 and PC-3. Short hairpin RNAs (shRNAs) were used to knock down target gene expression. Phagocytosis was assessed using a dual labeling technology in dendric cells co-cultured with cancer cells. The PERK gene promoter was cloned for dual luciferase assays. Chromatin immunoprecipitation (ChIP) was used to determine p53 protein-DNA binding activity. Immunocompetent mice and murine RM-1 prostate cancer cells were used for vaccination experiments. RESULTS MTX treatment induced typical characteristics of DAMP release, including increased cell surface exposure of calreticulin (CALR), and extracellular release of ATP and high mobility group box-1 (HMGB1) protein. MTX also enhanced phagocytosis by dendritic cells. Moreover, MTX treatment increased eukaryotic initiation factor 2α (eIF2α) S51 phosphorylation, which was reduced when PERK and GCN2 were silenced using shRNAs. In addition, PERK or GCN2 silencing significantly reduced MTX-induced release of DAMPs in vitro and anti-tumor immunity in vivo. MTX treatment also resulted in dendritic cell activation in mice, which was attenuated when PERK or GCN2 were silenced in cancer cells used for vaccination. Further analysis revealed that PERK and GCN2 expression was enhanced by MTX treatment, of which PERK, but not GCN2, was enhanced via a p53-dependent mechanism. CONCLUSION MTX triggers ICD by activating eIF2α via PERK/GCN2 upregulation in prostate cancer cells. MTX-induced PERK expression upregulation depends on the p53 pathway, while that of GCN2 requires further investigation.
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26
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El-Asmi F, McManus FP, Thibault P, Chelbi-Alix MK. Interferon, restriction factors and SUMO pathways. Cytokine Growth Factor Rev 2020; 55:37-47. [DOI: 10.1016/j.cytogfr.2020.03.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 03/18/2020] [Indexed: 12/21/2022]
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27
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Lan T, Tao A, Xu X, Kvietys P, Rui T. Peroxynitrite/PKR Axis Modulates the NLRP3 Inflammasome of Cardiac Fibroblasts. Front Immunol 2020; 11:558712. [PMID: 33101273 PMCID: PMC7545724 DOI: 10.3389/fimmu.2020.558712] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Accepted: 08/18/2020] [Indexed: 02/05/2023] Open
Abstract
Sepsis/endotoxemia activates the NLRP3 inflammasome of macrophages leading to the maturation and release of IL-1β, an important mediator of the inflammatory response. Reactive oxygen species have been implicated in NLRP3 inflammasome activation. Further, our preliminary studies indicated that LPS challenge of cardiac fibroblasts could phosphorylate protein kinase R (PKR) on threonine 451 and increase message for pro-IL-1 β. Thus, the major aim of the present study was to address the role of PKR and the oxidant, peroxynitrite, in the two-tiered function of the NLRP3 inflammasome (priming and activation). Materials and Methods: Isolated murine fibroblasts were primed with LPS (1 μg/ml) for 6 h and subsequently activated by an ATP (3 mM) challenge for 30 min to induce optimum functioning of the inflammasome. Increased levels of NLRP3 and pro-IL-1β protein (Western) were used as readouts for inflammasome priming, while activation of caspase 1 (p20) (Western) and secretion of IL-1β (ELISA) were indicative of inflammasome activation. Results: Inhibition of PKR (PKR inhibitor or siRNA) prior to priming with LPS prevented the LPS-induced increase in NLRP3 and pro-IL-1β expression. Further, inhibition of PKR after priming, but before activation, did not affect NLRP3 or pro-IL-1β protein levels, but markedly reduced the activation of caspase 1 and secretion of mature IL-1β. In a similar fashion, a peroxynitrite decomposition catalyst (Fe-TPPS) prevented both the priming and activation of the NLRP3 inflammasome. Finally, pretreatment of the fibroblasts with Fe-TPPS prevented the LPS-induced PKR phosphorylation (T451). Conclusion: Our results indicate that peroxynitrite-/PKR pathway modulates priming and activation of NLRP3 inflammasome in LPS/ATP challenged cardiac fibroblasts.
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Affiliation(s)
- Ting Lan
- Division of Cardiology, Department of Medicine, The Affiliated People's Hospital of Jiangsu University, Zhenjiang, China.,Critical Illness Research, Lawson Health Research Institute, London, ON, Canada.,Department of Laboratory Medicine, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
| | - Aibin Tao
- Division of Cardiology, Department of Medicine, The Affiliated People's Hospital of Jiangsu University, Zhenjiang, China.,Critical Illness Research, Lawson Health Research Institute, London, ON, Canada
| | - Xuemei Xu
- Critical Illness Research, Lawson Health Research Institute, London, ON, Canada.,Critical Care Western, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Peter Kvietys
- Department of Physiological Sciences, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
| | - Tao Rui
- Division of Cardiology, Department of Medicine, The Affiliated People's Hospital of Jiangsu University, Zhenjiang, China.,Critical Illness Research, Lawson Health Research Institute, London, ON, Canada.,Critical Care Western, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.,Departments of Medicine, Pathology and Laboratory Medicine, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
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28
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Cell fate determined by the activation balance between PKR and SPHK1. Cell Death Differ 2020; 28:401-418. [PMID: 32801355 PMCID: PMC7852545 DOI: 10.1038/s41418-020-00608-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 07/29/2020] [Accepted: 08/06/2020] [Indexed: 11/25/2022] Open
Abstract
Double-stranded RNA (dsRNA)-dependent protein kinase R (PKR) activation via autophosphorylation is the central cellular response to stress that promotes cell death or apoptosis. However, the key factors and mechanisms behind the simultaneous activation of pro-survival signaling pathways remain unknown. We have discovered a novel regulatory mechanism for the maintenance of cellular homeostasis that relies on the phosphorylation interplay between sphingosine kinase 1 (SPHK1) and PKR during exogenous stress. We identified SPHK1 as a previously unrecognized PKR substrate. Phosphorylated SPHK1, a central kinase, mediates the activation of PKR-induced pro-survival pathways by the S1P/S1PR1/MAPKs/IKKα signal axis, and antagonizes PKR-mediated endoplasmic reticulum (ER) stress signal transduction under stress conditions. Otherwise, phosphorylated SPHK1 also acts as the negative feedback factor, preferentially binding to the latent form of PKR at the C-terminal kinase motif, inhibiting the homodimerization of PKR, suppressing PKR autophosphorylation, and reducing the signaling strength for cell death and apoptosis. Our results suggest that the balance of the activation levels between PKR and SPHK1, a probable hallmark of homeostasis maintenance, determines cell fate during cellular stress response.
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29
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Piazzi M, Bavelloni A, Faenza I, Blalock W. Glycogen synthase kinase (GSK)-3 and the double-strand RNA-dependent kinase, PKR: When two kinases for the common good turn bad. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1867:118769. [PMID: 32512016 PMCID: PMC7273171 DOI: 10.1016/j.bbamcr.2020.118769] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 05/29/2020] [Accepted: 05/31/2020] [Indexed: 01/08/2023]
Abstract
Glycogen synthase kinase (GSK)-3α/β and the double-stranded RNA-dependent kinase PKR are two sentinel kinases that carry-out multiple similar yet distinct functions in both the cytosol and the nucleus. While these kinases belong to separate signal transduction cascades, they demonstrate an uncanny propensity to regulate many of the same proteins either through direct phosphorylation or by altering transcription/translation, including: c-MYC, NF-κB, p53 and TAU, as well as each another. A significant number of studies centered on the GSK3 kinases have led to the identification of the GSK3 interactome and a number of substrates, which link GSK3 activity to metabolic control, translation, RNA splicing, ribosome biogenesis, cellular division, DNA repair and stress/inflammatory signaling. Interestingly, many of these same pathways and processes are controlled by PKR, but unlike the GSK3 kinases, a clear picture of proteins interacting with PKR and a complete listing of its substrates is still missing. In this review, we take a detailed look at what is known about the PKR and GSK3 kinases, how these kinases interact to influence common cellular processes (innate immunity, alternative splicing, translation, glucose metabolism) and how aberrant activation of these kinases leads to diseases such as Alzheimer's disease (AD), diabetes mellitus (DM) and cancer. GSK3α/β and PKR are major regulators of cellular homeostasis and the response to stress/inflammation and infection. GSK3α/β and PKR interact with and/or modify many of the same proteins and affect the expression of similar genes. A balance between AKT and PKR nuclear signaling may be responsible for regulating the activation of nuclear GSK3β. GSK3α/β- and PKR-dependent signaling influence major molecular mechanisms of the cell through similar intermediates. Aberrant activation of GSK3α/β and PKR is highly involved in cancer, metabolic disorders, and neurodegenerative diseases.
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Affiliation(s)
- Manuela Piazzi
- Istituto di Genetica Molecolare "Luigi Luca Cavalli-Sforza", Consiglio Nazionale delle Ricerche (IGM-CNR), Bologna, Italy; IRCCS, Istituto Ortopedico Rizzoli, Bologna, Italy
| | - Alberto Bavelloni
- Laboratoria di Oncologia Sperimentale, IRCCS, Istituto Ortopedico Rizzoli, Bologna, Italy
| | - Irene Faenza
- Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy
| | - William Blalock
- Istituto di Genetica Molecolare "Luigi Luca Cavalli-Sforza", Consiglio Nazionale delle Ricerche (IGM-CNR), Bologna, Italy; IRCCS, Istituto Ortopedico Rizzoli, Bologna, Italy.
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30
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Mick E, Titov DV, Skinner OS, Sharma R, Jourdain AA, Mootha VK. Distinct mitochondrial defects trigger the integrated stress response depending on the metabolic state of the cell. eLife 2020; 9:e49178. [PMID: 32463360 PMCID: PMC7255802 DOI: 10.7554/elife.49178] [Citation(s) in RCA: 126] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2019] [Accepted: 05/04/2020] [Indexed: 12/13/2022] Open
Abstract
Mitochondrial dysfunction is associated with activation of the integrated stress response (ISR) but the underlying triggers remain unclear. We systematically combined acute mitochondrial inhibitors with genetic tools for compartment-specific NADH oxidation to trace mechanisms linking different forms of mitochondrial dysfunction to the ISR in proliferating mouse myoblasts and in differentiated myotubes. In myoblasts, we find that impaired NADH oxidation upon electron transport chain (ETC) inhibition depletes asparagine, activating the ISR via the eIF2α kinase GCN2. In myotubes, however, impaired NADH oxidation following ETC inhibition neither depletes asparagine nor activates the ISR, reflecting an altered metabolic state. ATP synthase inhibition in myotubes triggers the ISR via a distinct mechanism related to mitochondrial inner-membrane hyperpolarization. Our work dispels the notion of a universal path linking mitochondrial dysfunction to the ISR, instead revealing multiple paths that depend both on the nature of the mitochondrial defect and on the metabolic state of the cell.
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Affiliation(s)
- Eran Mick
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General HospitalBostonUnited States
- Broad InstituteCambridgeUnited States
- Department of Systems Biology, Harvard Medical SchoolBostonUnited States
| | - Denis V Titov
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General HospitalBostonUnited States
- Broad InstituteCambridgeUnited States
- Department of Systems Biology, Harvard Medical SchoolBostonUnited States
| | - Owen S Skinner
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General HospitalBostonUnited States
- Broad InstituteCambridgeUnited States
- Department of Systems Biology, Harvard Medical SchoolBostonUnited States
| | - Rohit Sharma
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General HospitalBostonUnited States
- Broad InstituteCambridgeUnited States
- Department of Systems Biology, Harvard Medical SchoolBostonUnited States
| | - Alexis A Jourdain
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General HospitalBostonUnited States
- Broad InstituteCambridgeUnited States
- Department of Systems Biology, Harvard Medical SchoolBostonUnited States
| | - Vamsi K Mootha
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General HospitalBostonUnited States
- Broad InstituteCambridgeUnited States
- Department of Systems Biology, Harvard Medical SchoolBostonUnited States
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31
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Eo H, Reed CH, Valentine RJ. Imoxin prevents dexamethasone-induced promotion of muscle-specific E3 ubiquitin ligases and stimulates anabolic signaling in C2C12 myotubes. Biomed Pharmacother 2020; 128:110238. [PMID: 32450522 DOI: 10.1016/j.biopha.2020.110238] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Revised: 04/30/2020] [Accepted: 05/03/2020] [Indexed: 12/26/2022] Open
Abstract
Muscle atrophy is the loss of skeletal muscle mass during several pathological conditions such as long-term fasting, aging, cancer, diabetes, sepsis and immune disorders. Glucocorticoids are known to trigger skeletal muscle atrophy. Dexamethasone (DEX), a synthetic glucocorticoid, induces skeletal muscle atrophy by suppression of protein synthesis and promotion of protein degradation. The double-stranded RNA (dsRNA)-activated protein kinase R (PKR) plays a significant role in mediating lipopolysaccharide-induced inflammation. However, pathological roles of PKR in muscle atrophy are not fully understood. The current study aimed to investigate the effect of imoxin, a PKR inhibitor, on DEX-induced muscle atrophy in C2C12 myotubes. Myotubes were incubated with imoxin at different concentrations with or without 5 μM DEX for 24 h. In the current study, imoxin treatment significantly reduced protein levels of MuRF1 and MAFbx induced by DEX by 88 ± 2% and MAFbx by 99 ± 0%, respectively. Moreover, 5 μM imoxin treatment reduced protein ubiquitination by 42 ± 4% and protein content of nuclear FoxO3α (77 ± 4%) in presence of DEX. Furthermore, 5 μM imoxin treatment stimulated Akt phosphorylation (195 ± 5%), mTOR phosphorylation (171 ± 21 %) and p70S6K1 phosphorylation (314 ± 31 %) under DEX-treated condition even though DEX treatment did not suppressed Akt/mTOR/p70S6K1 axis. These findings suggest that imoxin may protect against DEX-induced skeletal muscle atrophy by alleviating muscle specific E3 ubiquitin ligases and imoxin alone may promote protein synthesis via Akt/mTOR/S6K1 axis in muscle cells.
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Affiliation(s)
- Hyeyoon Eo
- Department of Kinesiology, Iowa State University, Ames, Iowa, United States; Interdepartmental Graduate Program in Nutritional Sciences, Iowa State University, Ames, Iowa, United States
| | - Carter H Reed
- Department of Kinesiology, Iowa State University, Ames, Iowa, United States; Interdepartmental Graduate Program in Nutritional Sciences, Iowa State University, Ames, Iowa, United States; Department of Food Science and Human Nutrition, Ames, Iowa, United States
| | - Rudy J Valentine
- Department of Kinesiology, Iowa State University, Ames, Iowa, United States; Interdepartmental Graduate Program in Nutritional Sciences, Iowa State University, Ames, Iowa, United States.
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32
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Ramesh R, Sattlegger E. Domain II of the translation elongation factor eEF1A is required for Gcn2 kinase inhibition. FEBS Lett 2020; 594:2266-2281. [PMID: 32359173 DOI: 10.1002/1873-3468.13803] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 03/18/2020] [Accepted: 04/01/2020] [Indexed: 12/15/2022]
Abstract
The signalling pathway governing general control nonderepressible (Gcn)2 kinase allows cells to cope with amino acid shortage. Under starvation, Gcn2 phosphorylates the translation initiation factor eukaryotic translation initiation factor (eIF)2α, triggering downstream events that ultimately allow cells to cope with starvation. Under nutrient-replete conditions, the translation elongation factor eEF1A binds Gcn2 to contribute to keeping Gcn2 inactive. Here, we aimed to map the regions in eEF1A involved in binding and/or regulating Gcn2. We find that eEF1A amino acids 1-221 and 222-315, containing most of domains I and II, respectively, bind Gcn2 in vitro. Overexpression of eEF1A lacking or containing domain III impairs eIF2α phosphorylation. While the latter reduces growth under starvation similarly to eEF1A lacking domain I, the former enhances growth in a Gcn2-dependent manner. Our studies suggest that domain II is required for Gcn2 inhibition and that eEF1A lacking domain III mainly affects the Gcn2 response pathway downstream of Gcn2.
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Affiliation(s)
- Rashmi Ramesh
- School of Natural and Computational Sciences, Massey University, Auckland, New Zealand
| | - Evelyn Sattlegger
- School of Natural and Computational Sciences, Massey University, Auckland, New Zealand
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33
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Malvezzi AM, Aricó M, Souza-Melo N, Dos Santos GP, Bittencourt-Cunha P, Holetz FB, Schenkman S. GCN2-Like Kinase Modulates Stress Granule Formation During Nutritional Stress in Trypanosoma cruzi. Front Cell Infect Microbiol 2020; 10:149. [PMID: 32373547 PMCID: PMC7176912 DOI: 10.3389/fcimb.2020.00149] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 03/20/2020] [Indexed: 12/24/2022] Open
Abstract
The integrated stress response in eukaryotic cells is an orchestrated pathway that leads to eukaryotic Initiation Factor 2 alpha subunit (eIF2α) phosphorylation at ser51 and ultimately activates pathways to mitigate cellular damages. Three putative kinases (Tck1, Tck2, and Tck3) are found in the Trypanosoma cruzi genome, the flagellated parasite that causes Chagas disease. These kinases present similarities to other eukaryotic eIF2α kinases, exhibiting a typical insertion loop in the kinase domain of the protein. We found that this insertion loop is conserved among kinase 1 of several T. cruzi strains but differs among various Kinetoplastidae species, suggesting unique roles. Kinase 1 is orthologous of GCN2 of several eukaryotes, which have been implicated in the eIF2α ser51 phosphorylation in situations that mainly affects the nutrients levels. Therefore, we further investigated the responses to nutritional stress of T. cruzi devoid of TcK1 generated by CRISPR/Cas9 gene replacement. In nutrient-rich conditions, replicative T. cruzi epimastigotes depleted of TcK1 proliferate as wild type cells but showed increased levels of polysomes relative to monosomes. Upon nutritional deprivation, the polysomes decreased more than in TcK1 depleted line. However, eIF2α is still phosphorylated in TcK1 depleted line, as in wild type parasites. eIF2α phosphorylation increased at longer incubations times, but KO parasites showed less accumulation of ribonucleoprotein granules containing ATP-dependent RNA helicase involved in mRNA turnover (DHH1) and Poly-A binding protein (PABP1). Additionally, the formation of metacyclic-trypomastigotes is increased in the absence of Tck1 compared to controls. These metacyclics, as well as tissue culture trypomastigotes derived from the TcK1 knockout line, were less infective to mammalian host cells, although replicated faster inside mammalian cells. These results indicate that GCN2-like kinase in T. cruzi affects stress granule formation, independently of eIF2α phosphorylation upon nutrient deprivation. It also modulates the fate of the parasites during differentiation, invasion, and intracellular proliferation.
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Affiliation(s)
- Amaranta Muniz Malvezzi
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Mirella Aricó
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Normanda Souza-Melo
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Gregory Pedroso Dos Santos
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Paula Bittencourt-Cunha
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | | | - Sergio Schenkman
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
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Selective inhibition of PKR improves vascular inflammation and remodelling in high fructose treated primary vascular smooth muscle cells. Biochim Biophys Acta Mol Basis Dis 2020; 1866:165606. [DOI: 10.1016/j.bbadis.2019.165606] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 10/25/2019] [Accepted: 11/11/2019] [Indexed: 12/14/2022]
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35
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Saavedra-García P, Martini F, Auner HW. Proteasome inhibition in multiple myeloma: lessons for other cancers. Am J Physiol Cell Physiol 2019; 318:C451-C462. [PMID: 31875696 DOI: 10.1152/ajpcell.00286.2019] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Cellular protein homeostasis (proteostasis) depends on the controlled degradation of proteins that are damaged or no longer required by the ubiquitin-proteasome system (UPS). The 26S proteasome is the principal executer of substrate-specific proteolysis in eukaryotic cells and regulates a myriad of cellular functions. Proteasome inhibitors were initially developed as chemical tools to study proteasomal function but rapidly became widely used anticancer drugs that are now used at all stages of treatment for the bone marrow cancer multiple myeloma (MM). Here, we review the mechanisms of action of proteasome inhibitors that underlie their preferential toxicity to MM cells, focusing on endoplasmic reticulum stress, depletion of amino acids, and effects on glucose and lipid metabolism. We also discuss mechanisms of resistance to proteasome inhibition such as autophagy and metabolic rewiring and what lessons we may learn from the success and failure of proteasome inhibition in MM for treating other cancers with proteostasis-targeting drugs.
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Affiliation(s)
- Paula Saavedra-García
- Cancer Cell Metabolism Group, Hugh and Josseline Langmuir Centre for Myeloma Research, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Francesca Martini
- Department of Translational Research on New Technologies in Medicine and Surgery, Hematology Unit, Ospedale Santa Chiara, Pisa, Italy
| | - Holger W Auner
- Cancer Cell Metabolism Group, Hugh and Josseline Langmuir Centre for Myeloma Research, Faculty of Medicine, Imperial College London, London, United Kingdom
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36
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Harding HP, Ordonez A, Allen F, Parts L, Inglis AJ, Williams RL, Ron D. The ribosomal P-stalk couples amino acid starvation to GCN2 activation in mammalian cells. eLife 2019; 8:50149. [PMID: 31749445 PMCID: PMC6919976 DOI: 10.7554/elife.50149] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 11/20/2019] [Indexed: 12/14/2022] Open
Abstract
The eukaryotic translation initiation factor 2α (eIF2α) kinase GCN2 is activated by amino acid starvation to elicit a rectifying physiological program known as the Integrated Stress Response (ISR). A role for uncharged tRNAs as activating ligands of yeast GCN2 is supported experimentally. However, mouse GCN2 activation has recently been observed in circumstances associated with ribosome stalling with no global increase in uncharged tRNAs. We report on a mammalian CHO cell-based CRISPR-Cas9 mutagenesis screen for genes that contribute to ISR activation by amino acid starvation. Disruption of genes encoding components of the ribosome P-stalk, uL10 and P1, selectively attenuated GCN2-mediated ISR activation by amino acid starvation or interference with tRNA charging without affecting the endoplasmic reticulum unfolded protein stress-induced ISR, mediated by the related eIF2α kinase PERK. Wildtype ribosomes isolated from CHO cells, but not those with P-stalk lesions, stimulated GCN2-dependent eIF2α phosphorylation in vitro. These observations support a model whereby lack of a cognate charged tRNA exposes a latent capacity of the ribosome P-stalk to activate GCN2 in cells and help explain the emerging link between ribosome stalling and ISR activation.
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Affiliation(s)
- Heather P Harding
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Adriana Ordonez
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Felicity Allen
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, United Kingdom
| | - Leopold Parts
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, United Kingdom
| | - Alison J Inglis
- Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Roger L Williams
- Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - David Ron
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
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37
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Hume A, Mühlberger E. Marburg Virus Viral Protein 35 Inhibits Protein Kinase R Activation in a Cell Type-Specific Manner. J Infect Dis 2019; 218:S403-S408. [PMID: 30165526 DOI: 10.1093/infdis/jiy473] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Protein kinase R (PKR) is a key antiviral protein involved in sensing and restricting viral infections. Here we analyzed the ability of Marburg virus (MARV) viral protein 35 (VP35) to inhibit PKR activation in human and bat cells. Similar to the related Ebola and Lloviu viruses, MARV VP35 was able to inhibit PKR activation in 293T cells. In contrast, we found that MARV VP35 did not inhibit human or bat PKR activation in human glioblastoma U-251-MG cells or a Rousettus aegyptiacus cell line. Additional experiments revealed that PACT, a known PKR regulator, was insufficient to rescue the ability of VP35 to inhibit PKR activation in these cells. Taken together, this study indicates that the ability of VP35 to inhibit PKR is cell type specific, potentially explaining discrepancies between the ability of filoviruses to potently block innate immune responses, and the high levels of interferon and interferon-stimulated genes observed in filovirus patients.
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Affiliation(s)
- Adam Hume
- Department of Microbiology, Boston University School of Medicine
- National Emerging Infectious Diseases Laboratories, Boston University, Massachusetts
| | - Elke Mühlberger
- Department of Microbiology, Boston University School of Medicine
- National Emerging Infectious Diseases Laboratories, Boston University, Massachusetts
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38
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The Leader Protein of Theiler's Virus Prevents the Activation of PKR. J Virol 2019; 93:JVI.01010-19. [PMID: 31292248 DOI: 10.1128/jvi.01010-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 07/02/2019] [Indexed: 11/20/2022] Open
Abstract
Leader (L) proteins encoded by cardioviruses are multifunctional proteins that contribute to innate immunity evasion. L proteins of Theiler's murine encephalomyelitis virus (TMEV), Saffold virus (SAFV), and encephalomyocarditis virus (EMCV) were reported to inhibit stress granule assembly in infected cells. Here, we show that TMEV L can act at two levels in the stress granule formation pathway: on the one hand, it can inhibit sodium arsenite-induced stress granule assembly without preventing eIF2α phosphorylation and, thus, acts downstream of eIF2α; on the other hand, it can inhibit eucaryotic translation initiation factor 2 alpha kinase 2 (PKR) activation and the consequent PKR-mediated eIF2α phosphorylation. Interestingly, coimmunostaining experiments revealed that PKR colocalizes with viral double-stranded RNA (dsRNA) in cells infected with L-mutant viruses but not in cells infected with the wild-type virus. Furthermore, PKR coprecipitated with dsRNA from cells infected with L-mutant viruses significantly more than from cells infected with the wild-type virus. These data strongly suggest that L blocks PKR activation by preventing the interaction between PKR and viral dsRNA. In infected cells, L also rendered PKR refractory to subsequent activation by poly(I·C). However, no interaction was observed between L and either dsRNA or PKR. Taken together, our results suggest that, unlike other viral proteins, L indirectly acts on PKR to negatively regulate its responsiveness to dsRNA.IMPORTANCE The leader (L) protein encoded by cardioviruses is a very short multifunctional protein that contributes to evasion of the host innate immune response. This protein notably prevents the formation of stress granules in infected cells. Using Theiler's virus as a model, we show that L proteins can act at two levels in the stress response pathway leading to stress granule formation, the most striking one being the inhibition of eucaryotic translation initiation factor 2 alpha kinase 2 (PKR) activation. Interestingly, the leader protein appears to inhibit PKR via a novel mechanism by rendering this kinase unable to detect double-stranded RNA, its typical activator. Unlike other viral proteins, such as influenza virus NS1, the leader protein appears to interact with neither PKR nor double-stranded RNA, suggesting that it acts indirectly to trigger the inhibition of the kinase.
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39
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Safran SA, Eckert DM, Leslie EA, Bass BL. PKR activation by noncanonical ligands: a 5'-triphosphate requirement versus antisense contamination. RNA (NEW YORK, N.Y.) 2019; 25:1192-1201. [PMID: 31239298 PMCID: PMC6800522 DOI: 10.1261/rna.071910.119] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 06/20/2019] [Indexed: 05/16/2023]
Abstract
Protein kinase RNA-activated (PKR) is an interferon-inducible kinase that is potently activated by long double-stranded RNA (dsRNA). In a previous study, we found that snoRNAs exhibit increased association with PKR in response to metabolic stress. While it was unclear if snoRNAs also activated PKR in cells, activation in vitro was observed. snoRNAs do not exhibit the double-stranded character typically required for activation of PKR, but some studies suggest such RNAs can activate PKR if triphosphorylated at the 5' terminus, or if they are able to form intermolecular dimers. To interrogate the mechanism of PKR activation by snoRNAs in vitro we focused on SNORD113. Using multiple methods for defining the 5'-phosphorylation state, we find that activation of PKR by SNORD113 does not require a 5'-triphosphate. Gel purification from a native gel followed by analysis using analytical ultracentrifugation showed that dimerization was also not responsible for activation. We isolated distinct conformers of SNORD113 from a native polyacrylamide gel and tracked the activating species to dsRNA formed from antisense RNA synthesized during in vitro transcription with T7 RNA polymerase. Similar studies with additional snoRNAs and small RNAs showed the generality of our results. Our studies suggest that a 5' triphosphate is not an activating ligand for PKR, and emphasize the insidious nature of antisense contamination.
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Affiliation(s)
- Sarah A Safran
- Department of Biochemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Debra M Eckert
- Department of Biochemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Evan A Leslie
- Department of Biochemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Brenda L Bass
- Department of Biochemistry, University of Utah, Salt Lake City, Utah 84112, USA
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40
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Lee YS, Kunkeaw N, Lee YS. Protein kinase R and its cellular regulators in cancer: An active player or a surveillant? WILEY INTERDISCIPLINARY REVIEWS-RNA 2019; 11:e1558. [PMID: 31231984 DOI: 10.1002/wrna.1558] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 05/24/2019] [Accepted: 05/28/2019] [Indexed: 12/12/2022]
Abstract
Protein kinase R (PKR), originally known as an antiviral protein, senses various stresses as well as pathogen-driven double-stranded RNAs. Thereby activated PKR provokes diverse downstream events, including eIF2α phosphorylation and nuclear factor kappa-light-chain-enhancer of activated B cells activation. Consequently, PKR induces apoptosis and inflammation, both of which are highly important in cancer as much as its original antiviral role. Therefore, cellular proteins and RNAs should tightly control PKR activity. PKR and its regulators are often dysregulated in cancer and it is undoubted that such dysregulation contributes to tumorigenesis. However, PKR's precise role in cancer is still in debate, due to incomprehensible and even contradictory data. In this review, we introduce important cellular PKR regulators and discuss about their roles in cancer. Among them, we pay particular attention to nc886, a PKR repressor noncoding RNA that has been identified relatively recently, because its expression pattern in cancer can explain interesting yet obscure oncologic aspects of PKR. Based on nc886 and its regulation of PKR, we have proposed a tumor surveillance model, which reconciles contradictory data about PKR in cancer. This article is categorized under: Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.
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Affiliation(s)
- Yong Sun Lee
- Department of Cancer Biomedical Science, Graduate School of Cancer Science and Policy, National Cancer Center, Goyang, Korea
| | - Nawapol Kunkeaw
- Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, Thailand
| | - Yeon-Su Lee
- Division of Clinical Research, Research Institute, National Cancer Center, Goyang, Korea
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41
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Darini C, Ghaddar N, Chabot C, Assaker G, Sabri S, Wang S, Krishnamoorthy J, Buchanan M, Aguilar-Mahecha A, Abdulkarim B, Deschenes J, Torres J, Ursini-Siegel J, Basik M, Koromilas AE. An integrated stress response via PKR suppresses HER2+ cancers and improves trastuzumab therapy. Nat Commun 2019; 10:2139. [PMID: 31086176 PMCID: PMC6513990 DOI: 10.1038/s41467-019-10138-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 04/23/2019] [Indexed: 12/21/2022] Open
Abstract
Trastuzumab is integral to HER2+ cancer treatment, but its therapeutic index is narrowed by the development of resistance. Phosphorylation of the translation initiation factor eIF2α (eIF2α-P) is the nodal point of the integrated stress response, which promotes survival or death in a context-dependent manner. Here, we show an anti-tumor function of the protein kinase PKR and its substrate eIF2α in a mouse HER2+ breast cancer model. The anti-tumor function depends on the transcription factor ATF4, which upregulates the CDK inhibitor P21CIP1 and activates JNK1/2. The PKR/eIF2α-P arm is induced by Trastuzumab in sensitive but not resistant HER2+ breast tumors. Also, eIF2α-P stimulation by the phosphatase inhibitor SAL003 substantially increases Trastuzumab potency in resistant HER2+ breast and gastric tumors. Increased eIF2α-P prognosticates a better response of HER2+ metastatic breast cancer patients to Trastuzumab therapy. Hence, the PKR/eIF2α-P arm antagonizes HER2 tumorigenesis whereas its pharmacological stimulation improves the efficacy of Trastuzumab therapy. The HER2 monoclonal antibody, Trastuzumab, is the current standard treatment for HER2+ cancers but resistance to therapy occurs. Here, the authors show that activation of the PKR/eIF2α-P pathway exhibits anti-tumor effects in HER2+ cancer and is required for the response to Trastuzumab.
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Affiliation(s)
- Cedric Darini
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, QC, H3T 1E2, Canada
| | - Nour Ghaddar
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, QC, H3T 1E2, Canada.,Division of Experimental Medicine, Department of Medicine, Faculty of Medicine, McGill University, Montreal, QC, H4A 3J1, Canada
| | - Catherine Chabot
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, QC, H3T 1E2, Canada
| | - Gloria Assaker
- Department of Pathology, Faculty of Medicine, McGill University, Montreal, QC, H3A 2B4, Canada.,Research Institute of McGill University Health Centre, Montreal, QC, H4A 3J1, Canada
| | - Siham Sabri
- Department of Pathology, Faculty of Medicine, McGill University, Montreal, QC, H3A 2B4, Canada.,Research Institute of McGill University Health Centre, Montreal, QC, H4A 3J1, Canada
| | - Shuo Wang
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, QC, H3T 1E2, Canada
| | - Jothilatha Krishnamoorthy
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, QC, H3T 1E2, Canada
| | - Marguerite Buchanan
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, QC, H3T 1E2, Canada
| | - Adriana Aguilar-Mahecha
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, QC, H3T 1E2, Canada
| | - Bassam Abdulkarim
- Research Institute of McGill University Health Centre, Montreal, QC, H4A 3J1, Canada.,Department of Oncology, Faculty of Medicine, McGill University, Montreal, QC, H4A 3T2, Canada
| | - Jean Deschenes
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB, T6G 2H7, Canada
| | - Jose Torres
- Department of Pathology, Faculty of Medicine, McGill University, Montreal, QC, H3A 2B4, Canada
| | - Josie Ursini-Siegel
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, QC, H3T 1E2, Canada.,Department of Oncology, Faculty of Medicine, McGill University, Montreal, QC, H4A 3T2, Canada
| | - Mark Basik
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, QC, H3T 1E2, Canada.,Department of Oncology, Faculty of Medicine, McGill University, Montreal, QC, H4A 3T2, Canada
| | - Antonis E Koromilas
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, QC, H3T 1E2, Canada. .,Department of Oncology, Faculty of Medicine, McGill University, Montreal, QC, H4A 3T2, Canada.
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42
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Wang J, Ji X, Liu J, Zhang X. Serine/Threonine Protein Kinase STK16. Int J Mol Sci 2019; 20:ijms20071760. [PMID: 30974739 PMCID: PMC6480182 DOI: 10.3390/ijms20071760] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 04/05/2019] [Accepted: 04/08/2019] [Indexed: 12/18/2022] Open
Abstract
STK16 (Ser/Thr kinase 16, also known as Krct/PKL12/MPSK1/TSF-1) is a myristoylated and palmitoylated Ser/Thr protein kinase that is ubiquitously expressed and conserved among all eukaryotes. STK16 is distantly related to the other kinases and belongs to the NAK kinase family that has an atypical activation loop architecture. As a membrane-associated protein that is primarily localized to the Golgi, STK16 has been shown to participate in the TGF-β signaling pathway, TGN protein secretion and sorting, as well as cell cycle and Golgi assembly regulation. This review aims to provide a comprehensive summary of the progress made in recent research about STK16, ranging from its distribution, molecular characterization, post-translational modification (fatty acylation and phosphorylation), interactors (GlcNAcK/DRG1/MAL2/Actin/WDR1), and related functions. As a relatively underexplored kinase, more studies are encouraged to unravel its regulation mechanisms and cellular functions.
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Affiliation(s)
- Junjun Wang
- High Magnetic Field Laboratory, Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China.
- Science Island Branch of Graduate School, University of Science and Technology of China, Hefei 230026, China.
| | - Xinmiao Ji
- High Magnetic Field Laboratory, Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China.
| | - Juanjuan Liu
- School of Life Sciences, Anhui University, Hefei 230601, China.
| | - Xin Zhang
- High Magnetic Field Laboratory, Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China.
- Science Island Branch of Graduate School, University of Science and Technology of China, Hefei 230026, China.
- Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China.
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43
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Parzych K, Saavedra-García P, Valbuena GN, Al-Sadah HA, Robinson ME, Penfold L, Kuzeva DM, Ruiz-Tellez A, Loaiza S, Holzmann V, Caputo V, Johnson DC, Kaiser MF, Karadimitris A, Lam EWF, Chevet E, Feldhahn N, Keun HC, Auner HW. The coordinated action of VCP/p97 and GCN2 regulates cancer cell metabolism and proteostasis during nutrient limitation. Oncogene 2019; 38:3216-3231. [PMID: 30626938 PMCID: PMC6756015 DOI: 10.1038/s41388-018-0651-z] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 12/05/2018] [Accepted: 12/07/2018] [Indexed: 12/30/2022]
Abstract
VCP/p97 regulates numerous cellular functions by mediating protein degradation through its segregase activity. Its key role in governing protein homoeostasis has made VCP/p97 an appealing anticancer drug target. Here, we provide evidence that VCP/p97 acts as a regulator of cellular metabolism. We found that VCP/p97 was tied to multiple metabolic processes on the gene expression level in a diverse range of cancer cell lines and in patient-derived multiple myeloma cells. Cellular VCP/p97 dependency to maintain proteostasis was increased under conditions of glucose and glutamine limitation in a range of cancer cell lines from different tissues. Moreover, glutamine depletion led to increased VCP/p97 expression, whereas VCP/p97 inhibition perturbed metabolic processes and intracellular amino acid turnover. GCN2, an amino acid-sensing kinase, attenuated stress signalling and cell death triggered by VCP/p97 inhibition and nutrient shortages and modulated ERK activation, autophagy, and glycolytic metabolite turnover. Together, our data point to an interconnected role of VCP/p97 and GCN2 in maintaining cancer cell metabolic and protein homoeostasis.
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Affiliation(s)
- Katarzyna Parzych
- Cancer Cell Protein Metabolism Group, Centre for Haematology, Department of Medicine, Imperial College London, London, UK
| | - Paula Saavedra-García
- Cancer Cell Protein Metabolism Group, Centre for Haematology, Department of Medicine, Imperial College London, London, UK
| | - Gabriel N Valbuena
- Division of Cancer, Department of Surgery and Cancer, Imperial College London, Hammersmith Hospital, London, UK
| | - Hibah A Al-Sadah
- Cancer Cell Protein Metabolism Group, Centre for Haematology, Department of Medicine, Imperial College London, London, UK
| | - Mark E Robinson
- Centre for Haematology, Department of Medicine, Imperial College London, London, UK
| | - Lucy Penfold
- Cancer Cell Protein Metabolism Group, Centre for Haematology, Department of Medicine, Imperial College London, London, UK
| | - Desislava M Kuzeva
- Cancer Cell Protein Metabolism Group, Centre for Haematology, Department of Medicine, Imperial College London, London, UK
| | - Angie Ruiz-Tellez
- Cancer Cell Protein Metabolism Group, Centre for Haematology, Department of Medicine, Imperial College London, London, UK
| | - Sandra Loaiza
- Cancer Cell Protein Metabolism Group, Centre for Haematology, Department of Medicine, Imperial College London, London, UK
| | - Viktoria Holzmann
- Cancer Cell Protein Metabolism Group, Centre for Haematology, Department of Medicine, Imperial College London, London, UK
| | - Valentina Caputo
- Centre for Haematology, Department of Medicine, Imperial College London, London, UK
| | - David C Johnson
- Division of Molecular Pathfology, Institute of Cancer Research, Sutton, UK
| | - Martin F Kaiser
- Division of Molecular Pathfology, Institute of Cancer Research, Sutton, UK
| | | | - Eric W-F Lam
- Division of Cancer, Department of Surgery and Cancer, Imperial College London, Hammersmith Hospital, London, UK
| | - Eric Chevet
- INSERM U1242, Chemistry, Oncogenesis, Stress, Signaling, Université de Rennes 1, Rennes, France
- Centre de Lutte Contre le Cancer Eugène Marquis Rennes, Rennes, France
| | - Niklas Feldhahn
- Centre for Haematology, Department of Medicine, Imperial College London, London, UK
| | - Hector C Keun
- Division of Cancer, Department of Surgery and Cancer, Imperial College London, Hammersmith Hospital, London, UK
| | - Holger W Auner
- Cancer Cell Protein Metabolism Group, Centre for Haematology, Department of Medicine, Imperial College London, London, UK.
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44
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Abstract
General control nonderepressible 2 (GCN2) phosphorylates eIF2α, regulating translation in response to nutritional stress. Here, we show that although tRNA stimulates purified, recombinant human GCN2 in vitro, mammalian ribosomes are even more potent GCN2 activators. Hydrogen/deuterium exchange–mass spectrometry (HDX-MS) showed GCN2 interacting with domain II of the uL10 P-stalk protein. The P-stalk is a uL10/P12/P22 pentameric complex that is part of the ribosomal GTPase-associated center. Recombinant human P-stalk greatly stimulates GCN2. Both domain II of uL10 and the C-terminal tails of P1 and P2 are necessary for maximal GCN2 activation. On actively translating ribosomes, the C-terminal tails of P1 and P2 are sequestered by elongation factors, suggesting P-stalk availability could link translational stress to GCN2 activation. Cells dynamically adjust their protein translation profile to maintain homeostasis in changing environments. During nutrient stress, the kinase general control nonderepressible 2 (GCN2) phosphorylates translation initiation factor eIF2α, initiating the integrated stress response (ISR). To examine the mechanism of GCN2 activation, we have reconstituted this process in vitro, using purified components. We find that recombinant human GCN2 is potently stimulated by ribosomes and, to a lesser extent, by tRNA. Hydrogen/deuterium exchange–mass spectrometry (HDX-MS) mapped GCN2–ribosome interactions to domain II of the uL10 subunit of the ribosomal P-stalk. Using recombinant, purified P-stalk, we showed that this domain of uL10 is the principal component of binding to GCN2; however, the conserved 14-residue C-terminal tails (CTTs) in the P1 and P2 P-stalk proteins are also essential for GCN2 activation. The HisRS-like and kinase domains of GCN2 show conformational changes upon binding recombinant P-stalk complex. Given that the ribosomal P-stalk stimulates the GTPase activity of elongation factors during translation, we propose that the P-stalk could link GCN2 activation to translational stress, leading to initiation of ISR.
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45
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Timalsina S, Arimoto-Matsuzaki K, Kitamura M, Xu X, Wenzhe Q, Ishigami-Yuasa M, Kagechika H, Hata Y. Chemical compounds that suppress hypoxia-induced stress granule formation enhance cancer drug sensitivity of human cervical cancer HeLa cells. J Biochem 2018; 164:381-391. [PMID: 30020475 DOI: 10.1093/jb/mvy062] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 07/12/2018] [Indexed: 12/21/2022] Open
Abstract
In eukaryotic cells, when exposed to certain types of stress including hypoxia, eIF2α is phosphorylated by several kinases including protein kinase R (PKR) and PKR-like endoplasmic reticulum kinase (PERK). Subsequently, protein translation is stopped and stress granules (SGs) are formed. Cancer cells form SGs under hypoxia. SGs accumulate apoptosis-related molecules and play anti-apoptotic roles. Thus, hypoxia-induced SG formation contributes to drug resistance in cancer cells. For this reason, inhibition of SG formation is expected to be beneficial in cancer therapy. To prove this concept, chemical reagents that inhibit SG formation are required as experimental tools. We searched for chemical compounds that suppress SG formation and identified that β-estradiol, progesterone, and stanolone (hereafter described as EPS) inhibit SG formation in human cervical cancer HeLa cells. As it turned out, EPS block PKR but not PERK, thus fail to suppress SG formation in most cancer cells, where SGs are formed via PERK. Nevertheless, in this study, we used HeLa cells as a model and demonstrated that EPS block hypoxia-induced SG formation in HeLa cells and consequently reduce drug resistance that HeLa cells acquire under hypoxia. Our findings support that inhibition of SG formation is a useful method to control cancers.
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Affiliation(s)
- Shikshya Timalsina
- Department of Medical Biochemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Kyoko Arimoto-Matsuzaki
- Department of Medical Biochemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Masami Kitamura
- Department of Medical Biochemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.,Diversity Diamond Unit Project Department, Student Support and Health Administration Organization, Tokyo Medical and Dental University, Tokyo, Japan
| | - Xiaoyin Xu
- Department of Medical Biochemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.,China Department of Breast Surgery, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Qiu Wenzhe
- Department of Medical Biochemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Mari Ishigami-Yuasa
- Chemical Biology Screening Center, Tokyo Medical and Dental University, Tokyo, Japan
| | - Hiroyuki Kagechika
- Chemical Biology Screening Center, Tokyo Medical and Dental University, Tokyo, Japan.,Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan
| | - Yutaka Hata
- Department of Medical Biochemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.,Center for Brain Integration Research, Tokyo Medical and Dental University, Tokyo, Japan
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46
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Bat-Erdene U, Quan E, Chan K, Lee BM, Matook W, Lee KY, Rosales JL. Neutrophil TLR4 and PKR are targets of breast cancer cell glycosaminoglycans and effectors of glycosaminoglycan-induced APRIL secretion. Oncogenesis 2018; 7:45. [PMID: 29904116 PMCID: PMC6002394 DOI: 10.1038/s41389-018-0058-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 05/03/2018] [Accepted: 05/15/2018] [Indexed: 12/20/2022] Open
Abstract
A proliferation-inducing ligand (APRIL), which induces survival and migration signals and tumor growth, is commonly observed in breast cancer tissues but is not often expressed in breast cancer cells themselves. Here, we examined whether breast cancer cells induce APRIL secretion from neutrophils, which are frequently recruited into the breast tumor microenvironment. We found that breast cancer cells do stimulate neutrophils to secrete APRIL through their glycosaminoglycans. Breast cancer cells depleted of heparan sulfate or chondroitin sulfate glycosaminoglycans lose their ability to induce APRIL secretion from neutrophils, and heparan sulfate and chondroitin sulfate can induce secretion that is comparable to that of breast cancer cell-induced secretion. While stimulation of the RNA-activated protein kinase (PKR) is sufficient to induce neutrophil APRIL secretion, both PKR and the toll-like receptor 4 (TLR4) are required for breast cancer cell glycosaminoglycan-induced secretion as separate and specific inhibition of TLR4 or PKR completely prevents the process, suggesting that breast cancer cell glycosaminoglycans target neutrophil TLR4 and PKR to trigger APRIL secretion. Thus, apart from the putative role of cell surface heparan sulfate in binding APRIL that leads to cell growth, we demonstrate that heparan sulfate, as well as chondroitin sulfate plays a novel role in promoting neutrophil secretion of APRIL that could lead to further cell growth. We propose that breast cancer cells take advantage of the neutrophil recruitment to the tumor microenvironment through the dual role of heparan sulfate as cell surface receptor or docking molecule for APRIL and as a ligand that induces neutrophil APRIL secretion to promote their own growth.
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Affiliation(s)
- Uilst Bat-Erdene
- Snyder Institute for Chronic Diseases, Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, T2N 4N1, Canada.,Arnie Charbonneau Cancer Institute, Department of Cell Biology and Anatomy, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Eric Quan
- Snyder Institute for Chronic Diseases, Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Kelvin Chan
- Snyder Institute for Chronic Diseases, Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Brianna-Marie Lee
- Snyder Institute for Chronic Diseases, Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, T2N 4N1, Canada.,Arnie Charbonneau Cancer Institute, Department of Cell Biology and Anatomy, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Wejdan Matook
- Arnie Charbonneau Cancer Institute, Department of Cell Biology and Anatomy, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Ki-Young Lee
- Arnie Charbonneau Cancer Institute, Department of Cell Biology and Anatomy, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Jesusa L Rosales
- Snyder Institute for Chronic Diseases, Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, T2N 4N1, Canada.
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47
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Abstract
The liver has a unique ability of regenerating after injuries or partial loss of its mass. The mechanisms responsible for liver regeneration - mostly occurring when the hepatic tissue is damaged or functionally compromised by metabolic stress - have been studied in considerable detail over the last few decades, because this phenomenon has both basic-biology and clinical relevance. More specifically, recent interest has been focusing on the widespread occurrence of abnormal nutritional habits in the Western world that result in an increased prevalence of non-alcoholic fatty liver disease (NAFLD). NAFLD is closely associated with insulin resistance and dyslipidemia, and it represents a major clinical challenge. The disease may progress to steatohepatitis with persistent inflammation and progressive liver damage, both of which will compromise regeneration under conditions of partial hepatectomy in surgical oncology or in liver transplantation procedures. Here, we analyze the impact of ER stress and SIRT1 in lipid metabolism and in fatty liver pathology, and their consequences on liver regeneration. Moreover, we discuss the fine interplay between ER stress and SIRT1 functioning when contextualized to liver regeneration. An improved understanding of the cellular and molecular intricacies contributing to liver regeneration could be of great clinical relevance in areas as diverse as obesity, metabolic syndrome and type 2 diabetes, as well as oncology and transplantation.
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Affiliation(s)
| | - Giuseppe Servillo
- Department of Experimental Medicine, University of Perugia, Perugia, Italy
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48
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Kalra J, Mangali SB, Bhat A, Dhar I, Udumula MP, Dhar A. Imoxin attenuates high fructose-induced oxidative stress and apoptosis in renal epithelial cells via downregulation of protein kinase R pathway. Fundam Clin Pharmacol 2018; 32:297-305. [DOI: 10.1111/fcp.12352] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 01/24/2018] [Accepted: 02/05/2018] [Indexed: 12/17/2022]
Affiliation(s)
- Jaspreet Kalra
- Department of Pharmacy; Birla Institute of Technology and Sciences Pilani; Hyderabad Campus, Jawahar Nagar, Shameerpet Hyderabad Andhra Pradesh 500078 India
| | - Suresh Babu Mangali
- Department of Pharmacy; Birla Institute of Technology and Sciences Pilani; Hyderabad Campus, Jawahar Nagar, Shameerpet Hyderabad Andhra Pradesh 500078 India
| | - Audesh Bhat
- Department of Molecular Biology; Central University of Jammu; Jammu Jammu and Kashmir 181143 India
| | - Indu Dhar
- Department of Clinical Sciences; University of Bergen; Bergen 5007 Norway
| | - Mary Priyanka Udumula
- Department of Pharmacy; Birla Institute of Technology and Sciences Pilani; Hyderabad Campus, Jawahar Nagar, Shameerpet Hyderabad Andhra Pradesh 500078 India
| | - Arti Dhar
- Department of Pharmacy; Birla Institute of Technology and Sciences Pilani; Hyderabad Campus, Jawahar Nagar, Shameerpet Hyderabad Andhra Pradesh 500078 India
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49
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Mesclon F, Lambert-Langlais S, Carraro V, Parry L, Hainault I, Jousse C, Maurin AC, Bruhat A, Fafournoux P, Averous J. Decreased ATF4 expression as a mechanism of acquired resistance to long-term amino acid limitation in cancer cells. Oncotarget 2018; 8:27440-27453. [PMID: 28460466 PMCID: PMC5432347 DOI: 10.18632/oncotarget.15828] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 02/12/2017] [Indexed: 02/06/2023] Open
Abstract
The uncontrolled growth of tumor can lead to the formation of area deprived in nutrients. Due to their high genetic instability, tumor cells can adapt and develop resistance to this pro-apoptotic environment. Among the resistance mechanisms, those involved in the resistance to long-term amino acid restriction are not elucidated. A long-term amino acid restriction is particularly deleterious since nine of them cannot be synthetized by the cells. In order to determine how cancer cells face a long-term amino acid deprivation, we developed a cell model selected for its capacity to resist a long-term amino acid limitation. We exerted a selection pressure on mouse embryonic fibroblast to isolate clones able to survive with low amino acid concentration. The study of several clones revealed an alteration of the eiF2α/ATF4 pathway. Compared to the parental cells, the clones exhibited a decreased expression of the transcription factor ATF4 and its target genes. Likewise, the knock-down of ATF4 in parental cells renders them resistant to amino acid deprivation. Moreover, this association between a low level of ATF4 protein and the resistance to amino acid deprivation was also observed in the cancer cell line BxPC-3. This resistance was abolished when ATF4 was overexpressed. Therefore, decreasing ATF4 expression may be one important mechanism for cancer cells to survive under prolonged amino acid deprivation.
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Affiliation(s)
- Florent Mesclon
- Université Clermont Auvergne, INRA, UNH, Unité de Nutrition Humaine, CRNH Auvergne, F-63000 Clermont-Ferrand, France
| | - Sarah Lambert-Langlais
- Department of Medical Biochemistry and Molecular Biology, CHU de Clermont-Ferrand, 63003 Clermont-Ferrand Cedex 1, France
| | - Valérie Carraro
- Université Clermont Auvergne, INRA, UNH, Unité de Nutrition Humaine, CRNH Auvergne, F-63000 Clermont-Ferrand, France
| | - Laurent Parry
- Université Clermont Auvergne, INRA, UNH, Unité de Nutrition Humaine, CRNH Auvergne, F-63000 Clermont-Ferrand, France
| | - Isabelle Hainault
- Institute of Cardiometabolism and Nutrition, Université Pierre et Marie Curie, INSERM, UMR S1138, Centre de Recherche des Cordeliers, 75006 Paris, France
| | - Céline Jousse
- Université Clermont Auvergne, INRA, UNH, Unité de Nutrition Humaine, CRNH Auvergne, F-63000 Clermont-Ferrand, France
| | - Anne-Catherine Maurin
- Université Clermont Auvergne, INRA, UNH, Unité de Nutrition Humaine, CRNH Auvergne, F-63000 Clermont-Ferrand, France
| | - Alain Bruhat
- Université Clermont Auvergne, INRA, UNH, Unité de Nutrition Humaine, CRNH Auvergne, F-63000 Clermont-Ferrand, France
| | - Pierre Fafournoux
- Université Clermont Auvergne, INRA, UNH, Unité de Nutrition Humaine, CRNH Auvergne, F-63000 Clermont-Ferrand, France
| | - Julien Averous
- Université Clermont Auvergne, INRA, UNH, Unité de Nutrition Humaine, CRNH Auvergne, F-63000 Clermont-Ferrand, France
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50
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Zhang M, Gallego-Delgado J, Fernandez-Arias C, Waters NC, Rodriguez A, Tsuji M, Wek RC, Nussenzweig V, Sullivan WJ. Inhibiting the Plasmodium eIF2α Kinase PK4 Prevents Artemisinin-Induced Latency. Cell Host Microbe 2017; 22:766-776.e4. [DOI: 10.1016/j.chom.2017.11.005] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2017] [Revised: 09/26/2017] [Accepted: 11/10/2017] [Indexed: 01/09/2023]
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