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Burnett SB, Culver AM, Simon TA, Rowson T, Frederick K, Palmer K, Murray SA, Davis SW, Patel RC. A frameshift mutation in the murine Prkra gene causes dystonia and exhibits abnormal cerebellar development and reduced eIF2α phosphorylation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.04.597421. [PMID: 38895245 PMCID: PMC11185611 DOI: 10.1101/2024.06.04.597421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Mutations in Prkra gene, which encodes PACT/RAX cause early onset primary dystonia DYT-PRKRA, a movement disorder that disrupts coordinated muscle movements. PACT/RAX activates protein kinase R (PKR, aka EIF2AK2) by a direct interaction in response to cellular stressors to mediate phosphorylation of the α subunit of the eukaryotic translation initiation factor 2 (eIF2α). Mice homozygous for a naturally arisen, recessively inherited frameshift mutation, Prkra lear-5J exhibit progressive dystonia. In the present study, we investigate the biochemical and developmental consequences of the Prkra lear-5J mutation. Our results indicate that the truncated PACT/RAX protein retains its ability to interact with PKR, however, it inhibits PKR activation. Furthermore, mice homozygous for the mutation have abnormalities in the cerebellar development as well as a severe lack of dendritic arborization of Purkinje neurons. Additionally, reduced eIF2α phosphorylation is noted in the cerebellums and Purkinje neurons of the homozygous Prkra lear-5J mice. These results indicate that PACT/RAX mediated regulation of PKR activity and eIF2α phosphorylation plays a role in cerebellar development and contributes to the dystonia phenotype resulting from this mutation.
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Affiliation(s)
| | | | | | | | | | - Kristina Palmer
- The Jackson Laboratory, 600 Main St., Bar Harbor, ME 04609, USA
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2
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Duran J, Poolsup S, Allers L, Lemus MR, Cheng Q, Pu J, Salemi M, Phinney B, Jia J. A mechanism that transduces lysosomal damage signals to stress granule formation for cell survival. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.29.587368. [PMID: 38617306 PMCID: PMC11014484 DOI: 10.1101/2024.03.29.587368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
Lysosomal damage poses a significant threat to cell survival. Our previous work has reported that lysosomal damage induces stress granule (SG) formation. However, the importance of SG formation in determining cell fate and the precise mechanisms through which lysosomal damage triggers SG formation remains unclear. Here, we show that SG formation is initiated via a novel calcium-dependent pathway and plays a protective role in promoting cell survival in response to lysosomal damage. Mechanistically, we demonstrate that during lysosomal damage, ALIX, a calcium-activated protein, transduces lysosomal damage signals by sensing calcium leakage to induce SG formation by controlling the phosphorylation of eIF2α. ALIX modulates eIF2α phosphorylation by regulating the association between PKR and its activator PACT, with galectin-3 exerting a negative effect on this process. We also found this regulatory event of SG formation occur on damaged lysosomes. Collectively, these investigations reveal novel insights into the precise regulation of SG formation triggered by lysosomal damage, and shed light on the interaction between damaged lysosomes and SGs. Importantly, SG formation is significant for promoting cell survival in the physiological context of lysosomal damage inflicted by SARS-CoV-2 ORF3a, adenovirus infection, Malaria hemozoin, proteopathic tau as well as environmental hazard silica.
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Affiliation(s)
- Jacob Duran
- Center for Global Health, Department of Internal Medicine, University of New Mexico Health Sciences Center, Albuquerque, NM 87106, USA
- Autophagy, Inflammation and Metabolism Center of Biochemical Research Excellence, Albuquerque, NM 87106, USA
| | - Suttinee Poolsup
- Center for Global Health, Department of Internal Medicine, University of New Mexico Health Sciences Center, Albuquerque, NM 87106, USA
- Autophagy, Inflammation and Metabolism Center of Biochemical Research Excellence, Albuquerque, NM 87106, USA
| | - Lee Allers
- Autophagy, Inflammation and Metabolism Center of Biochemical Research Excellence, Albuquerque, NM 87106, USA
- Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM 87106, USA
| | - Monica Rosas Lemus
- Autophagy, Inflammation and Metabolism Center of Biochemical Research Excellence, Albuquerque, NM 87106, USA
- Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM 87106, USA
| | - Qiuying Cheng
- Center for Global Health, Department of Internal Medicine, University of New Mexico Health Sciences Center, Albuquerque, NM 87106, USA
| | - Jing Pu
- Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM 87106, USA
| | - Michelle Salemi
- Proteomics Core Facility, University of California Davis Genome Center, University of California, Davis, CA 95616, USA
| | - Brett Phinney
- Proteomics Core Facility, University of California Davis Genome Center, University of California, Davis, CA 95616, USA
| | - Jingyue Jia
- Center for Global Health, Department of Internal Medicine, University of New Mexico Health Sciences Center, Albuquerque, NM 87106, USA
- Autophagy, Inflammation and Metabolism Center of Biochemical Research Excellence, Albuquerque, NM 87106, USA
- Lead Contact
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Kang S, Xu Z, Liu S, Wu S, Chen H, Xu L, Qin Q, Wei J. Function analysis of fish PACT gene in response to virus infection. FISH & SHELLFISH IMMUNOLOGY 2024; 144:109304. [PMID: 38103849 DOI: 10.1016/j.fsi.2023.109304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 11/21/2023] [Accepted: 12/13/2023] [Indexed: 12/19/2023]
Abstract
PACT (interferon-inducible double-stranded RNA-dependent protein kinase activator A) is a cellular protein which can activate PKR in dsRNA-independent manner. However, the role of PACT in fish virus infection remains largely unknown. In this study, a PACT homologue from grouper (Epinephelus coioides)(EcPACT) was cloned and characterized. The open reading frame of EcPACT has a full length of 924 bp and encodes a protein of 307 amino acids with a predicted molecular weight of 33.29 kDa. Similar to mammals, EcPACT contains three dsRBD domains. EcPACT shares 99.67 % homology with E. lanceolatus. Real-time fluorescence quantitative PCR results showed that EcPACT mRNA was widely expressed in all tissues and abundantly expressed in brain, blood, head kidney and kidney. In addition, SGIV and RGNNV infection significantly upregulated the transcript levels of EcPACT. Subcellular localization analysis showed that EcPACT was mainly distributed in the nucleus. Overexpression of EcPACT inhibited the replication of SGIV and RGNNV in vitro and positively regulated the expression of interferon (IFN) and pro-inflammatory factors. The results provide a better understanding of the relationship between PACT and viral infection in fish.
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Affiliation(s)
- Shaozhu Kang
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China; Nansha-South China Agricultural University Fishery Research Institute Guangzhou, Guangzhou, 511400, China
| | - Zhuqing Xu
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China; Nansha-South China Agricultural University Fishery Research Institute Guangzhou, Guangzhou, 511400, China
| | - Shaoli Liu
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China; Nansha-South China Agricultural University Fishery Research Institute Guangzhou, Guangzhou, 511400, China
| | - Siting Wu
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China; Nansha-South China Agricultural University Fishery Research Institute Guangzhou, Guangzhou, 511400, China
| | - Hong Chen
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China; Nansha-South China Agricultural University Fishery Research Institute Guangzhou, Guangzhou, 511400, China
| | - Linting Xu
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China; Nansha-South China Agricultural University Fishery Research Institute Guangzhou, Guangzhou, 511400, China
| | - Qiwei Qin
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China; Nansha-South China Agricultural University Fishery Research Institute Guangzhou, Guangzhou, 511400, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China.
| | - Jingguang Wei
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China; Nansha-South China Agricultural University Fishery Research Institute Guangzhou, Guangzhou, 511400, China.
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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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Collados Rodríguez M, Maillard P, Journeaux A, Komarova AV, Najburg V, David RYS, Helynck O, Guo M, Zhong J, Baize S, Tangy F, Jacob Y, Munier-Lehmann H, Meurs EF. Novel Antiviral Molecules against Ebola Virus Infection. Int J Mol Sci 2023; 24:14791. [PMID: 37834238 PMCID: PMC10573436 DOI: 10.3390/ijms241914791] [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: 08/30/2023] [Revised: 09/19/2023] [Accepted: 09/22/2023] [Indexed: 10/15/2023] Open
Abstract
Infection with Ebola virus (EBOV) is responsible for hemorrhagic fever in humans with a high mortality rate. Combined efforts of prevention and therapeutic intervention are required to tackle highly variable RNA viruses, whose infections often lead to outbreaks. Here, we have screened the 2P2I3D chemical library using a nanoluciferase-based protein complementation assay (NPCA) and isolated two compounds that disrupt the interaction of the EBOV protein fragment VP35IID with the N-terminus of the dsRNA-binding proteins PKR and PACT, involved in IFN response and/or intrinsic immunity, respectively. The two compounds inhibited EBOV infection in cell culture as well as infection by measles virus (MV) independently of IFN induction. Consequently, we propose that the compounds are antiviral by restoring intrinsic immunity driven by PACT. Given that PACT is highly conserved across mammals, our data support further testing of the compounds in other species, as well as against other negative-sense RNA viruses.
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Affiliation(s)
- Mila Collados Rodríguez
- School of Infection & Immunity (SII), College of Medical, Veterinary and Life Sciences (MVLS), Sir Michael Stoker Building, MRC-University of Glasgow Centre for Virus Research (CVR), Glasgow G61 1QH, UK
- Unité Hépacivirus et Immunité Innée, CNRS, UMR 3569, Département de Virologie, Institut Pasteur, 75015 Paris, France; (P.M.); (E.F.M.)
| | - Patrick Maillard
- Unité Hépacivirus et Immunité Innée, CNRS, UMR 3569, Département de Virologie, Institut Pasteur, 75015 Paris, France; (P.M.); (E.F.M.)
| | - Alexandra Journeaux
- Unit of Biology of Emerging Viral Infections, Institut Pasteur, 69007 Lyon, France; (A.J.); (S.B.)
| | - Anastassia V. Komarova
- Interactomics, RNA and Immunity Laboratory, Institut Pasteur, 75015 Paris, France;
- Unité de Génomique Virale et Vaccination, Institut Pasteur, 75015 Paris, France; (V.N.); (R.-Y.S.D.); (F.T.)
- Université Paris Cité, 75013 Paris, France;
| | - Valérie Najburg
- Unité de Génomique Virale et Vaccination, Institut Pasteur, 75015 Paris, France; (V.N.); (R.-Y.S.D.); (F.T.)
- Université Paris Cité, 75013 Paris, France;
| | - Raul-Yusef Sanchez David
- Unité de Génomique Virale et Vaccination, Institut Pasteur, 75015 Paris, France; (V.N.); (R.-Y.S.D.); (F.T.)
- Blizard Institute—Faculty of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK
| | - Olivier Helynck
- Unité de Chimie et Biocatalyse, CNRS, UMR 3523, Institut Pasteur, Université de Paris, 75015 Paris, France; (O.H.); (H.M.-L.)
| | - Mingzhe Guo
- CAS Key Laboratory of Molecular Virology and Immunology, Unit of Viral Hepatitis, Shanghai Institute of Immunity and Infection, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Shanghai 200023, China; (M.G.); (J.Z.)
| | - Jin Zhong
- CAS Key Laboratory of Molecular Virology and Immunology, Unit of Viral Hepatitis, Shanghai Institute of Immunity and Infection, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Shanghai 200023, China; (M.G.); (J.Z.)
| | - Sylvain Baize
- Unit of Biology of Emerging Viral Infections, Institut Pasteur, 69007 Lyon, France; (A.J.); (S.B.)
| | - Frédéric Tangy
- Unité de Génomique Virale et Vaccination, Institut Pasteur, 75015 Paris, France; (V.N.); (R.-Y.S.D.); (F.T.)
- Université Paris Cité, 75013 Paris, France;
| | - Yves Jacob
- Université Paris Cité, 75013 Paris, France;
- Unité Génétique Moléculaire des Virus à ARN, CNRS, UMR 3569, Département de Virologie, Institut Pasteur, 75015 Paris, France
| | - Hélène Munier-Lehmann
- Unité de Chimie et Biocatalyse, CNRS, UMR 3523, Institut Pasteur, Université de Paris, 75015 Paris, France; (O.H.); (H.M.-L.)
| | - Eliane F. Meurs
- Unité Hépacivirus et Immunité Innée, CNRS, UMR 3569, Département de Virologie, Institut Pasteur, 75015 Paris, France; (P.M.); (E.F.M.)
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6
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Frederick K, Patel RC. Luteolin protects DYT- PRKRA cells from apoptosis by suppressing PKR activation. Front Pharmacol 2023; 14:1118725. [PMID: 36874028 PMCID: PMC9974672 DOI: 10.3389/fphar.2023.1118725] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 02/06/2023] [Indexed: 02/17/2023] Open
Abstract
DYT-PRKRA is a movement disorder caused by mutations in the PRKRA gene, which encodes for PACT, the protein activator of interferon-induced, double-stranded RNA (dsRNA)-activated protein kinase PKR. PACT brings about PKR's catalytic activation by a direct binding in response to stress signals and activated PKR phosphorylates the translation initiation factor eIF2α. Phosphorylation of eIF2α is the central regulatory event that is part of the integrated stress response (ISR), an evolutionarily conserved intracellular signaling network essential for adapting to environmental stresses to maintain healthy cells. A dysregulation of either the level or the duration of eIF2α phosphorylation in response to stress signals causes the normally pro-survival ISR to become pro-apoptotic. Our research has established that the PRKRA mutations reported to cause DYT-PRKRA lead to enhanced PACT-PKR interactions causing a dysregulation of ISR and an increased sensitivity to apoptosis. We have previously identified luteolin, a plant flavonoid, as an inhibitor of the PACT-PKR interaction using high-throughput screening of chemical libraries. Our results presented in this study indicate that luteolin is markedly effective in disrupting the pathological PACT-PKR interactions to protect DYT-PRKRA cells against apoptosis, thus suggesting a therapeutic option for using luteolin to treat DYT-PRKRA and possibly other diseases resulting from enhanced PACT-PKR interactions.
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Affiliation(s)
- Kenneth Frederick
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
| | - Rekha C Patel
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
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7
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Cheng X, Jiang Z, Feng Z, Sun Z, Lu S, Xu X, Mao H, Hu C. Grass carp (Ctenopharyngodon idella) Trans-Activation-Responsive RNA-binding protein 2 (TARBP2) inhibits apoptosis by decreasing PKR phosphorylation. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2022; 133:104425. [PMID: 35452690 DOI: 10.1016/j.dci.2022.104425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 04/16/2022] [Accepted: 04/16/2022] [Indexed: 06/14/2023]
Abstract
PKR plays a significant role in IFN antiviral responses and in mediating apoptosis. Its activity is crucial for cellular antiviral and subsequent recovery. In mammalian cells, Protein Activator of the Interferon-induced Protein Kinase (PACT) and Trans-Activation-Responsive RNA-Binding Protein 2 (TARBP2) have the opposite effect on PKR activity in a dsRNA independent manner. There are some corresponding regulators of PKR in fish, too. In previous studies, we found that grass carp PACT can activate PKR in dsRNA independent manner. In this study, we tried to find out the effect of grass carp TARBP2 on PKR regulation. Grass carp TARBP2 expression is significantly increased at 6h post-poly I:C stimulation in CIK cells and grass carp tissues, indicating that it may play a role in poly I:C-mediated immune response. Then, we found that CiTARBP2 interacts with CiPKR and CiPACT, suggesting that it may regulate PKR activity by direct interaction with PKR or its regulators. Further, poly I:C promotes the phosphorylation of CiTARBP2 and enhances the interaction of CiTARBP2 and CiPKR. Finally, over-expression of CiTARBP2 decreases CiPKR phosphorylation and inhibits PKR-induced apoptosis. Therefore, our study reveals that CiTARBP2 can bind to CiPKR, CiPACT and CiTARBP2. The phosphorylated TARBP2 has stronger affinity to PKR, which results in the decrease of PKR phosphorylation and inhibition of cell apoptosis.
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Affiliation(s)
- Xining Cheng
- College of Life Science, Key Lab of Aquatic Resources and Utilization of Jiangxi Province, Nanchang University, Nanchang, 330031, China
| | - Zeyin Jiang
- College of Life Science, Key Lab of Aquatic Resources and Utilization of Jiangxi Province, Nanchang University, Nanchang, 330031, China
| | - Zhiqing Feng
- College of Life Science, Key Lab of Aquatic Resources and Utilization of Jiangxi Province, Nanchang University, Nanchang, 330031, China
| | - Zhichao Sun
- College of Life Science, Key Lab of Aquatic Resources and Utilization of Jiangxi Province, Nanchang University, Nanchang, 330031, China
| | - Shina Lu
- College of Life Science, Key Lab of Aquatic Resources and Utilization of Jiangxi Province, Nanchang University, Nanchang, 330031, China
| | - Xiaowen Xu
- College of Life Science, Key Lab of Aquatic Resources and Utilization of Jiangxi Province, Nanchang University, Nanchang, 330031, China
| | - Huiling Mao
- College of Life Science, Key Lab of Aquatic Resources and Utilization of Jiangxi Province, Nanchang University, Nanchang, 330031, China
| | - Chengyu Hu
- College of Life Science, Key Lab of Aquatic Resources and Utilization of Jiangxi Province, Nanchang University, Nanchang, 330031, China.
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8
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Dogan AE, Hamid SM, Yildirim AD, Yildirim Z, Sen G, Riera CE, Gottlieb RA, Erbay E. PACT establishes a posttranscriptional brake on mitochondrial biogenesis by promoting the maturation of miR-181c. J Biol Chem 2022; 298:102050. [PMID: 35598827 PMCID: PMC9218515 DOI: 10.1016/j.jbc.2022.102050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 05/11/2022] [Accepted: 05/13/2022] [Indexed: 11/29/2022] Open
Abstract
The double-stranded RNA-dependent protein kinase activating protein (PACT), an RNA-binding protein that is part of the RNA-induced silencing complex, plays a key role in miR-mediated translational repression. Previous studies showed that PACT regulates the expression of various miRs, selects the miR strand to be loaded onto RNA-induced silencing complex, and determines proper miR length. Apart from PACT's role in mediating the antiviral response in immune cells, what PACT does in other cell types is unknown. Strikingly, it has also been shown that cold exposure leads to marked downregulation of PACT protein in mouse brown adipose tissue (BAT), where mitochondrial biogenesis and metabolism play a central role. Here, we show that PACT establishes a posttranscriptional brake on mitochondrial biogenesis (mitobiogenesis) by promoting the maturation of miR-181c, a key suppressor of mitobiogenesis that has been shown to target mitochondrial complex IV subunit I (Mtco1) and sirtuin 1 (Sirt1). Consistently, we found that a partial reduction in PACT expression is sufficient to enhance mitobiogenesis in brown adipocytes in culture as well as during BAT activation in mice. In conclusion, we demonstrate an unexpected role for PACT in the regulation of mitochondrial biogenesis and energetics in cells and BAT.
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Affiliation(s)
- Asli E Dogan
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA; Department of Molecular Biology and Genetics, National Nanotechnology Center, Bilkent University, Ankara, Turkey
| | - Syed M Hamid
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Asli D Yildirim
- Department of Molecular Biology and Genetics, National Nanotechnology Center, Bilkent University, Ankara, Turkey
| | - Zehra Yildirim
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA; Department of Molecular Biology and Genetics, National Nanotechnology Center, Bilkent University, Ankara, Turkey
| | - Ganes Sen
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Celine E Riera
- Department of Biomedical Sciences, Center for Neural Science and Medicine, Cedars-Sinai Medical Center, Los Angeles, California, USA; Department of Neurology, Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA; David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | - Roberta A Gottlieb
- Department of Cardiology, Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Ebru Erbay
- David Geffen School of Medicine, University of California, Los Angeles, California, USA; Department of Cardiology, Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA.
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Chukwurah E, Farabaugh KT, Guan BJ, Ramakrishnan P, Hatzoglou M. A tale of two proteins: PACT and PKR and their roles in inflammation. FEBS J 2021; 288:6365-6391. [PMID: 33387379 PMCID: PMC9248962 DOI: 10.1111/febs.15691] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 12/14/2020] [Accepted: 12/29/2020] [Indexed: 12/12/2022]
Abstract
Inflammation is a pathological hallmark associated with bacterial and viral infections, autoimmune diseases, genetic disorders, obesity and diabetes, as well as environmental stresses including physical and chemical trauma. Among numerous proteins regulating proinflammatory signaling, very few such as Protein kinase R (PKR), have been shown to play an all-pervading role in inflammation induced by varied stimuli. PKR was initially characterized as an interferon-inducible gene activated by viral double-stranded RNA with a role in protein translation inhibition. However, it has become increasingly clear that PKR is involved in multiple pathways that promote inflammation in response to stress activation, both dependent on and independent of its cellular protein activator of PKR (PACT). In this review, we discuss the signaling pathways that contribute to the initiation of inflammation, including Toll-like receptor, interferon, and RIG-I-like receptor signaling, as well as inflammasome activation. We go on to discuss the specific roles that PKR and PACT play in such proinflammatory signaling, as well as in metabolic syndrome- and environmental stress-induced inflammation.
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Affiliation(s)
- Evelyn Chukwurah
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH 44106
| | - Kenneth T. Farabaugh
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH 44106
| | - Bo-Jhih Guan
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH 44106
| | | | - Maria Hatzoglou
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH 44106
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10
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Neault N, O’Reilly S, Baig AT, Plaza-Diaz J, Azimi M, Farooq F, Baird SD, MacKenzie A. High-throughput kinome-RNAi screen identifies protein kinase R activator (PACT) as a novel genetic modifier of CUG foci integrity in myotonic dystrophy type 1 (DM1). PLoS One 2021; 16:e0256276. [PMID: 34520479 PMCID: PMC8439471 DOI: 10.1371/journal.pone.0256276] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 08/03/2021] [Indexed: 11/24/2022] Open
Abstract
Myotonic Dystrophy Type 1 (DM1) is the most common form of adult muscular dystrophy (~1:8000). In DM1, expansion of CTG trinucleotide repeats in the 3' untranslated region of the dystrophia myotonica protein kinase (DMPK) gene results in DMPK mRNA hairpin structures which aggregate as insoluble ribonuclear foci and sequester several RNA-binding proteins. The resulting sequestration and misregulation of important splicing factors, such as muscleblind-like 1 (MBNL1), causes the aberrant expression of fetal transcripts for several genes that contribute to the disease phenotype. Previous work has shown that antisense oligonucleotide-mediated disaggregation of the intranuclear foci has the potential to reverse downstream anomalies. To explore whether the nuclear foci are, to some extent, controlled by cell signalling pathways, we have performed a screen using a small interfering RNA (siRNA) library targeting 518 protein kinases to look at kinomic modulation of foci integrity. RNA foci were visualized by in situ hybridization of a fluorescent-tagged (CAG)10 probe directed towards the expanded DMPK mRNA and the cross-sectional area and number of foci per nuclei were recorded. From our screen, we have identified PACT (protein kinase R (PKR) activator) as a novel modulator of foci integrity and have shown that PACT knockdown can both increase MBNL1 protein levels; however, these changes are not suffcient for significant correction of downstream spliceopathies.
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Affiliation(s)
- Nafisa Neault
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
| | - Sean O’Reilly
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
| | - Aiman Tariq Baig
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
| | - Julio Plaza-Diaz
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
| | - Mehrdad Azimi
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
| | - Faraz Farooq
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
| | - Stephen D. Baird
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
| | - Alex MacKenzie
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
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11
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Ukhueduan B, Chukwurah E, Patel RC. Regulation of PKR activation and apoptosis during oxidative stress by TRBP phosphorylation. Int J Biochem Cell Biol 2021; 137:106030. [PMID: 34174402 DOI: 10.1016/j.biocel.2021.106030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 06/09/2021] [Accepted: 06/18/2021] [Indexed: 11/25/2022]
Abstract
Transactivation response element RNA-binding protein (TRBP or TARBP2) originally identified as a pro-viral cellular protein in human immunodeficiency virus (HIV) replication is also a regulator of microRNA biogenesis and cellular stress response. TRBP inhibits the catalytic activity of interferon-induced double-stranded RNA (dsRNA)-activated protein kinase (PKR) during viral infections and cell stress thereby regulating stress-induced signaling pathways. During cellular stress, PKR is catalytically activated transiently by its protein activator PACT and TRBP inhibits PKR to bring about a timely cellular recovery. We have previously established that TRBP phosphorylated after oxidative stress binds to and inhibits PKR more efficiently promoting cell survival. In this study, we investigated if phosphorylation of TRBP enhances its interaction with PACT to bring about additional PKR inhibition. Our data establishes that phosphorylation of TRBP has no effect on PACT-TRBP interaction and TRBP's inhibitory actions on PKR are mediated exclusively by its enhanced interaction with PKR. Cells lacking TRBP are more sensitive to apoptosis in response to oxidative stress and show persistent PKR activation. These results establish that PKR inhibition by stress-induced TRBP phosphorylation occurs by its direct binding to PKR and is important for preventing apoptosis due to sustained PKR activation.
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Affiliation(s)
- Benedicth Ukhueduan
- Department of Biological Sciences, University of South Carolina, Columbia, SC, 29208, USA
| | - Evelyn Chukwurah
- Department of Biological Sciences, University of South Carolina, Columbia, SC, 29208, USA
| | - Rekha C Patel
- Department of Biological Sciences, University of South Carolina, Columbia, SC, 29208, USA.
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12
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Vaughn LS, Chukwurah E, Patel RC. Opposite actions of two dsRNA-binding proteins PACT and TRBP on RIG-I mediated signaling. Biochem J 2021; 478:493-510. [PMID: 33459340 PMCID: PMC7919947 DOI: 10.1042/bcj20200987] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/13/2021] [Accepted: 01/18/2021] [Indexed: 02/07/2023]
Abstract
An integral aspect of innate immunity is the ability to detect foreign molecules of viral origin to initiate antiviral signaling via pattern recognition receptors (PRRs). One such receptor is the RNA helicase retinoic acid inducible gene 1 (RIG-I), which detects and is activated by 5'triphosphate uncapped double stranded RNA (dsRNA) as well as the cytoplasmic viral mimic dsRNA polyI:C. Once activated, RIG-I's CARD domains oligomerize and initiate downstream signaling via mitochondrial antiviral signaling protein (MAVS), ultimately inducing interferon (IFN) production. Another dsRNA binding protein PACT, originally identified as the cellular protein activator of dsRNA-activated protein kinase (PKR), is known to enhance RIG-I signaling in response to polyI:C treatment, in part by stimulating RIG-I's ATPase and helicase activities. TAR-RNA-binding protein (TRBP), which is ∼45% homologous to PACT, inhibits PKR signaling by binding to PKR as well as by sequestration of its' activators, dsRNA and PACT. Despite the extensive homology and similar structure of PACT and TRBP, the role of TRBP has not been explored much in RIG-I signaling. This work focuses on the effect of TRBP on RIG-I signaling and IFN production. Our results indicate that TRBP acts as an inhibitor of RIG-I signaling in a PACT- and PKR-independent manner. Surprisingly, this inhibition is independent of TRBP's post-translational modifications that are important for other signaling functions of TRBP, but TRBP's dsRNA-binding ability is essential. Our work has major implications on viral susceptibility, disease progression, and antiviral immunity as it demonstrates the regulatory interplay between PACT and TRBP IFN production.
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Affiliation(s)
- Lauren S. Vaughn
- Department of Biology, University of South Carolina, Columbia, SC 29210
| | | | - Rekha C Patel
- Department of Biology, University of South Carolina, Columbia, SC 29210
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13
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Dystonia 16 (DYT16) mutations in PACT cause dysregulated PKR activation and eIF2α signaling leading to a compromised stress response. Neurobiol Dis 2020; 146:105135. [PMID: 33049316 DOI: 10.1016/j.nbd.2020.105135] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 09/17/2020] [Accepted: 10/07/2020] [Indexed: 12/17/2022] Open
Abstract
Dystonia 16 (DYT16) is caused by mutations in PACT, the protein activator of interferon-induced double-stranded RNA-activated protein kinase (PKR). PKR regulates the integrated stress response (ISR) via phosphorylation of the translation initiation factor eIF2α. This post-translational modification attenuates general protein synthesis while concomitantly triggering enhanced translation of a few specific transcripts leading either to recovery and homeostasis or cellular apoptosis depending on the intensity and duration of stress signals. PKR plays a regulatory role in determining the cellular response to viral infections, oxidative stress, endoplasmic reticulum (ER) stress, and growth factor deprivation. In the absence of stress, both PACT and PKR are bound by their inhibitor transactivation RNA-binding protein (TRBP) thereby keeping PKR inactive. Under conditions of cellular stress these inhibitory interactions dissociate facilitating PACT-PACT interactions critical for PKR activation. While both PACT-TRBP and PKR-TRBP interactions are pro-survival, PACT-PACT and PACT-PKR interactions are pro-apoptotic. In this study we evaluate if five DYT16 substitution mutations alter PKR activation and ISR. Our results indicate that the mutant DYT16 proteins show stronger PACT-PACT interactions and enhanced PKR activation. In DYT16 patient derived lymphoblasts the enhanced PACT-PKR interactions and heightened PKR activation leads to a dysregulation of ISR and increased apoptosis. More importantly, this enhanced sensitivity to ER stress can be rescued by luteolin, which disrupts PACT-PKR interactions. Our results not only demonstrate the impact of DYT16 mutations on regulation of ISR and DYT16 etiology but indicate that therapeutic interventions could be possible after a further evaluation of such strategies.
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14
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Burnett SB, Vaughn LS, Strom JM, Francois A, Patel RC. A truncated PACT protein resulting from a frameshift mutation reported in movement disorder DYT16 triggers caspase activation and apoptosis. J Cell Biochem 2019; 120:19004-19018. [PMID: 31246344 DOI: 10.1002/jcb.29223] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 06/04/2019] [Indexed: 01/21/2023]
Abstract
Protein Activator (PACT) activates the interferon (IFN)-induced double-stranded (ds) RNA-activated protein kinase (PKR) in response to stress signals. Oxidative stress and endoplasmic reticulum (ER) stress causes PACT-mediated PKR activation, which leads to phosphorylation of translation initiation factor eIF2α, inhibition of protein synthesis, and apoptosis. A dominantly inherited form of early-onset dystonia 16 (DYT16) has been identified to arise due to a frameshift (FS) mutation in PACT. To examine the effect of the resulting truncated mutant PACT protein on the PKR pathway, we examined the biochemical properties of the mutant protein and its effect on mammalian cells. Our results indicate that the FS mutant protein loses its ability to bind dsRNA as well as its ability to interact with PKR while surprisingly retaining the ability to interact with PACT and PKR-inhibitory protein TRBP. The truncated FS mutant protein, when expressed as a fusion protein with a N-terminal fluorescent mCherry tag aggregates in mammalian cells to induce apoptosis via activation of caspases both in a PKR- and PACT-dependent as well as independent manner. Our results indicate that interaction of FS mutant protein with PKR inhibitor TRBP can dissociate PACT from the TRBP-PACT complex resulting in PKR activation and consequent apoptosis. These findings are relevant to diseases resulting from protein aggregation especially since the PKR activation is a characteristic of several neurodegenerative conditions.
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Affiliation(s)
- Samuel B Burnett
- Department of Biological Sciences University of South Carolina, University of South Carolina, Columbia, South Carolina
| | - Lauren S Vaughn
- Department of Biological Sciences University of South Carolina, University of South Carolina, Columbia, South Carolina
| | - Joelle M Strom
- Department of Biological Sciences University of South Carolina, University of South Carolina, Columbia, South Carolina
| | - Ashley Francois
- Department of Biological Sciences University of South Carolina, University of South Carolina, Columbia, South Carolina
| | - Rekha C Patel
- Department of Biological Sciences University of South Carolina, University of South Carolina, Columbia, South Carolina
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15
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Brisse ME, Ly H. Hemorrhagic Fever-Causing Arenaviruses: Lethal Pathogens and Potent Immune Suppressors. Front Immunol 2019; 10:372. [PMID: 30918506 PMCID: PMC6424867 DOI: 10.3389/fimmu.2019.00372] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 02/14/2019] [Indexed: 12/22/2022] Open
Abstract
Hemorrhagic fevers (HF) resulting from pathogenic arenaviral infections have traditionally been neglected as tropical diseases primarily affecting African and South American regions. There are currently no FDA-approved vaccines for arenaviruses, and treatments have been limited to supportive therapy and use of non-specific nucleoside analogs, such as Ribavirin. Outbreaks of arenaviral infections have been limited to certain geographic areas that are endemic but known cases of exportation of arenaviruses from endemic regions and socioeconomic challenges for local control of rodent reservoirs raise serious concerns about the potential for larger outbreaks in the future. This review synthesizes current knowledge about arenaviral evolution, ecology, transmission patterns, life cycle, modulation of host immunity, disease pathogenesis, as well as discusses recent development of preventative and therapeutic pursuits against this group of deadly viral pathogens.
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Affiliation(s)
- Morgan E Brisse
- Biochemistry, Molecular Biology, and Biophysics Graduate Program, University of Minnesota, St. Paul, MN, United States.,Department of Veterinary and Biomedical Sciences, University of Minnesota, St. Paul, MN, United States
| | - Hinh Ly
- Department of Veterinary and Biomedical Sciences, University of Minnesota, St. Paul, MN, United States
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16
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Abstract
Detection of double-stranded RNAs (dsRNAs) is a central mechanism of innate immune defense in many organisms. We here discuss several families of dsRNA-binding proteins involved in mammalian antiviral innate immunity. These include RIG-I-like receptors, protein kinase R, oligoadenylate synthases, adenosine deaminases acting on RNA, RNA interference systems, and other proteins containing dsRNA-binding domains and helicase domains. Studies suggest that their functions are highly interdependent and that their interdependence could offer keys to understanding the complex regulatory mechanisms for cellular dsRNA homeostasis and antiviral immunity. This review aims to highlight their interconnectivity, as well as their commonalities and differences in their dsRNA recognition mechanisms.
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Affiliation(s)
- Sun Hur
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA; .,Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts 02115, USA
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17
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Ding Z, Fang L, Yuan S, Zhao L, Wang X, Long S, Wang M, Wang D, Foda MF, Xiao S. The nucleocapsid proteins of mouse hepatitis virus and severe acute respiratory syndrome coronavirus share the same IFN-β antagonizing mechanism: attenuation of PACT-mediated RIG-I/ MDA5 activation. Oncotarget 2018; 8:49655-49670. [PMID: 28591694 PMCID: PMC5564796 DOI: 10.18632/oncotarget.17912] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 05/01/2017] [Indexed: 01/08/2023] Open
Abstract
Coronaviruses (CoVs) are a huge threat to both humans and animals and have evolved elaborate mechanisms to antagonize interferons (IFNs). Nucleocapsid (N) protein is the most abundant viral protein in CoV-infected cells, and has been identified as an innate immunity antagonist in several CoVs, including mouse hepatitis virus (MHV) and severe acute respiratory syndrome (SARS)-CoV. However, the underlying molecular mechanism(s) remain unclear. In this study, we found that MHV N protein inhibited Sendai virus and poly(I:C)-induced IFN-β production by targeting a molecule upstream of retinoic acid-induced gene I (RIG-I) and melanoma differentiation gene 5 (MDA5). Further studies showed that both MHV and SARS-CoV N proteins directly interacted with protein activator of protein kinase R (PACT), a cellular dsRNA-binding protein that can bind to RIG-I and MDA5 to activate IFN production. The N–PACT interaction sequestered the association of PACT and RIG-I/MDA5, which in turn inhibited IFN-β production. However, the N proteins from porcine epidemic diarrhea virus (PEDV) and porcine reproductive and respiratory syndrome virus (PRRSV), which are also classified in the order Nidovirales, did not interact and counteract with PACT. Taken together, our present study confirms that both MHV and SARS-CoV N proteins can perturb the function of cellular PACT to circumvent the innate antiviral response. However, this strategy does not appear to be used by all CoVs N proteins.
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Affiliation(s)
- Zhen Ding
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Liurong Fang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Shuangling Yuan
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Ling Zhao
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Xunlei Wang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Siwen Long
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Mohan Wang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Dang Wang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Mohamed Frahat Foda
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Shaobo Xiao
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
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18
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Stress-induced TRBP phosphorylation enhances its interaction with PKR to regulate cellular survival. Sci Rep 2018; 8:1020. [PMID: 29348664 PMCID: PMC5773696 DOI: 10.1038/s41598-018-19360-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 12/29/2017] [Indexed: 12/20/2022] Open
Abstract
Transactivation response element RNA-binding protein (TRBP or TARBP2) initially identified to play an important role in human immunodeficiency virus (HIV) replication also has emerged as a regulator of microRNA biogenesis. In addition, TRBP functions in signaling pathways by negatively regulating the interferon-induced double-stranded RNA (dsRNA)-activated protein kinase (PKR) during viral infections and cell stress. During cellular stress, PKR is activated and phosphorylates the α subunit of the eukaryotic translation factor eIF2, leading to the cessation of general protein synthesis. TRBP inhibits PKR activity by direct interaction as well as by binding to PKR’s two known activators, dsRNA and PACT, thus preventing their interaction with PKR. In this study, we demonstrate for the first time that TRBP is phosphorylated in response to oxidative stress and upon phosphorylation, inhibits PKR more efficiently promoting cell survival. These results establish that PKR regulation through stress-induced TRBP phosphorylation is an important mechanism ensuring cellular recovery and preventing apoptosis due to sustained PKR activation.
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19
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Chukwurah E, Willingham V, Singh M, Castillo-Azofeifa D, Patel RC. Contribution of the two dsRBM motifs to the double-stranded RNA binding and protein interactions of PACT. J Cell Biochem 2018; 119:3598-3607. [PMID: 29231267 DOI: 10.1002/jcb.26561] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 12/01/2017] [Indexed: 11/12/2022]
Abstract
PACT is a stress-modulated activator of protein kinase PKR (protein kinase, RNA activated), which is involved in antiviral innate immune responses and stress-induced apoptosis. Stress-induced phosphorylation of PACT is essential for PACT's increased association with PKR leading to PKR activation, phosphorylation of translation initiation factor eIF2α, inhibition of protein synthesis, and apoptosis. PACT-induced PKR activation is negatively regulated by TRBP (transactivation response element RNA-binding protein), which dissociates from PACT after PACT phosphorylation in response to stress signals. The conserved double-stranded RNA binding motifs (dsRBMs) in PKR, PACT, and TRBP mediate protein-protein interactions, and the stress-dependent phosphorylation of PACT changes the relative strengths of PKR-PACT, PACT-TRBP, and PACT-PACT interactions to bring about a timely and transient PKR activation. This regulates the general kinetics as well as level of eIF2α phosphorylation, thereby influencing the cellular response to stress either as recovery and survival or elimination by apoptosis. In the present study, we evaluated the effect of specific mutations within PACT's two evolutionarily conserved dsRBMs on dsRNA-binding, and protein-protein interactions between PKR, PACT, and TRBP. Our data show that the two motifs contribute to varying extents in dsRNA binding, and protein interactions. These findings indicate that although the dsRBM motifs have high sequence conservation, their functional contribution in the context of the whole proteins needs to be determined by mutational analysis. Furthermore, using a PACT mutant that is deficient in PACT-PACT interaction but competent for PACT-PKR interaction, we demonstrate that PACT-PACT interaction is essential for efficient PKR activation.
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Affiliation(s)
- Evelyn Chukwurah
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina
| | - Victoria Willingham
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina
| | - Madhurima Singh
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina
| | | | - Rekha C Patel
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina
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20
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Dabo S, Maillard P, Collados Rodriguez M, Hansen MD, Mazouz S, Bigot DJ, Tible M, Janvier G, Helynck O, Cassonnet P, Jacob Y, Bellalou J, Gatignol A, Patel RC, Hugon J, Munier-Lehmann H, Meurs EF. Inhibition of the inflammatory response to stress by targeting interaction between PKR and its cellular activator PACT. Sci Rep 2017; 7:16129. [PMID: 29170442 PMCID: PMC5701060 DOI: 10.1038/s41598-017-16089-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 11/07/2017] [Indexed: 02/07/2023] Open
Abstract
PKR is a cellular kinase involved in the regulation of the integrative stress response (ISR) and pro-inflammatory pathways. Two N-terminal dsRNA Binding Domains (DRBD) are required for activation of PKR, by interaction with either dsRNA or PACT, another cellular DRBD-containing protein. A role for PKR and PACT in inflammatory processes linked to neurodegenerative diseases has been proposed and raised interest for pharmacological PKR inhibitors. However, the role of PKR in inflammation is subject to controversy. We identified the flavonoid luteolin as an inhibitor of the PKR/PACT interaction at the level of their DRBDs using high-throughput screening of chemical libraries by homogeneous time-resolved fluorescence. This was further validated using NanoLuc-Based Protein Complementation Assay. Luteolin inhibits PKR phosphorylation, the ISR and the induction of pro-inflammatory cytokines in human THP1 macrophages submitted to oxidative stress and toll-like receptor (TLR) agonist. Similarly, luteolin inhibits induction of pro-inflammatory cytokines in murine microglial macrophages. In contrast, luteolin increased activation of the inflammasome, in a PKR-independent manner. Collectively, these data delineate the importance of PKR in the inflammation process to the ISR and induction of pro-inflammatory cytokines. Pharmacological inhibitors of PKR should be used in combination with drugs targeting directly the inflammasome.
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Affiliation(s)
- Stephanie Dabo
- Unité Hepacivirus and Innate Immunity, Institut Pasteur, 75015, Paris, France.,CNRS, UMR 3569, Paris, France
| | - Patrick Maillard
- Unité Hepacivirus and Innate Immunity, Institut Pasteur, 75015, Paris, France.,CNRS, UMR 3569, Paris, France
| | - Milagros Collados Rodriguez
- Unité Hepacivirus and Innate Immunity, Institut Pasteur, 75015, Paris, France.,CNRS, UMR 3569, Paris, France
| | - Marianne Doré Hansen
- Unité Hepacivirus and Innate Immunity, Institut Pasteur, 75015, Paris, France.,CNRS, UMR 3569, Paris, France.,Department of Clinical and Molecular Medicine, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, 7006, Trondheim, Norway
| | - Sabrina Mazouz
- Unité Hepacivirus and Innate Immunity, Institut Pasteur, 75015, Paris, France.,CNRS, UMR 3569, Paris, France
| | - Donna-Joe Bigot
- Unité Hepacivirus and Innate Immunity, Institut Pasteur, 75015, Paris, France.,CNRS, UMR 3569, Paris, France
| | - Marion Tible
- Center of Cognitive Neurology, Lariboisière Hospital AP-HP University Paris Diderot, Paris, France.,Inserm, U942, Paris, France
| | - Geneviève Janvier
- Unité Hepacivirus and Innate Immunity, Institut Pasteur, 75015, Paris, France.,CNRS, UMR 3569, Paris, France
| | - Olivier Helynck
- Unité de Chimie et Biocatalyse, Institut Pasteur, 75015, Paris, France.,CNRS, UMR3523, Paris, France
| | - Patricia Cassonnet
- CNRS, UMR 3569, Paris, France.,Unité de Génétique Moléculaire des Virus à ARN, Institut Pasteur, Université Paris Diderot, Paris, France
| | - Yves Jacob
- CNRS, UMR 3569, Paris, France.,Unité de Génétique Moléculaire des Virus à ARN, Institut Pasteur, Université Paris Diderot, Paris, France
| | - Jacques Bellalou
- Plate-forme des protéines recombinantes, Institut Pasteur, 75015, CNRS UMR 3528, Paris, France
| | - Anne Gatignol
- Virus-Cell Interactions Laboratory, Lady Davis Institute for Medical Research, Department of Medicine, department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
| | - Rekha C Patel
- University of South Carolina, Department of Biological Sciences, Columbia, South Carolina, 29208, USA
| | - Jacques Hugon
- Center of Cognitive Neurology, Lariboisière Hospital AP-HP University Paris Diderot, Paris, France.,Inserm, U942, Paris, France
| | - Hélène Munier-Lehmann
- Unité de Chimie et Biocatalyse, Institut Pasteur, 75015, Paris, France.,CNRS, UMR3523, Paris, France
| | - Eliane F Meurs
- Unité Hepacivirus and Innate Immunity, Institut Pasteur, 75015, Paris, France. .,CNRS, UMR 3569, Paris, France.
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21
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Clinical and therapeutic potential of protein kinase PKR in cancer and metabolism. Expert Rev Mol Med 2017; 19:e9. [PMID: 28724458 DOI: 10.1017/erm.2017.11] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The protein kinase R (PKR, also called EIF2AK2) is an interferon-inducible double-stranded RNA protein kinase with multiple effects on cells that plays an active part in the cellular response to numerous types of stress. PKR has been extensively studied and documented for its relevance as an antiviral agent and a cell growth regulator. Recently, the role of PKR related to metabolism, inflammatory processes, cancer and neurodegenerative diseases has gained interest. In this review, we summarise and discuss the involvement of PKR in several cancer signalling pathways and the dual role that this kinase plays in cancer disease. We emphasise the importance of PKR as a molecular target for both conventional chemotherapeutics and emerging treatments based on novel drugs, and its potential as a biomarker and therapeutic target for several pathologies. Finally, we discuss the impact that the recent knowledge regarding PKR involvement in metabolism has in our understanding of the complex processes of cancer and metabolism pathologies, highlighting the translational research establishing the clinical and therapeutic potential of this pleiotropic kinase.
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22
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ADAR1 and PACT contribute to efficient translation of transcripts containing HIV-1 trans-activating response (TAR) element. Biochem J 2017; 474:1241-1257. [PMID: 28167698 PMCID: PMC5363390 DOI: 10.1042/bcj20160964] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 01/30/2017] [Accepted: 02/06/2017] [Indexed: 12/15/2022]
Abstract
Human immunodeficiency virus type 1 (HIV-1) has evolved various measures to counter the host cell's innate antiviral response during the course of infection. Interferon (IFN)-stimulated gene products are produced following HIV-1 infection to limit viral replication, but viral proteins and RNAs counteract their effect. One such mechanism is specifically directed against the IFN-induced Protein Kinase PKR, which is centrally important to the cellular antiviral response. In the presence of viral RNAs, PKR is activated and phosphorylates the translation initiation factor eIF2α. This shuts down the synthesis of both host and viral proteins, allowing the cell to mount an effective antiviral response. PACT (protein activator of PKR) is a cellular protein activator of PKR, primarily functioning to activate PKR in response to cellular stress. Recent studies have indicated that during HIV-1 infection, PACT's normal cellular function is compromised and that PACT is unable to activate PKR. Using various reporter systems and in vitro kinase assays, we establish in this report that interactions between PACT, ADAR1 and HIV-1-encoded Tat protein diminish the activation of PKR in response to HIV-1 infection. Our results highlight an important pathway by which HIV-1 transcripts subvert the host cell's antiviral activities to enhance their translation.
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23
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Smad7 knockdown activates protein kinase RNA-associated eIF2α pathway leading to colon cancer cell death. Cell Death Dis 2017; 8:e2681. [PMID: 28300830 PMCID: PMC5386514 DOI: 10.1038/cddis.2017.103] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 02/10/2017] [Accepted: 02/13/2017] [Indexed: 02/06/2023]
Abstract
Upregulation of Smad7, an inhibitor of transforming growth factor-β1 (TGF-β1), occurs in sporadic colorectal cancer (CRC) and knockdown of Smad7 inhibits CRC cell growth, a phenomenon that associates with decreased expression of cell division cycle 25 homolog A and arrest of cells in the S phase of the cell cycle. These findings occur in CRC cells unresponsive to TGF-β1, thus suggesting the existence of a Smad7-mediated TGF-β1-independent mechanism that controls CRC cell behavior. Here we show that Smad7 inhibition with a specific Smad7 antisense oligonucleotide upregulates eukaryotic translation initiation factor 2α (eIF2α) phosphorylation, a transcription factor involved in the regulation of cell cycle arrest and induction of cell death, and induces activating transcription factor 4 (ATF4) and CCAAT/enhancer binding protein homology protein (CHOP), two downstream targets of eIF2α. Among the upstream kinases that control eIF2α phosphorylation, the serine-threonine protein kinase RNA (PKR), but not general control non-derepressible 2 (GCN2) and protein kinase RNA-like endoplasmic reticulum kinase (PERK), is activated by Smad7 knockdown. PKR silencing abolishes Smad7 antisense-induced eIF2α phosphorylation and ATF4/CHOP induction, thereby preventing Smad7 antisense-driven cell death. Smad7 inhibition diminishes interaction of PKR with protein kinase inhibitor p58 (p58IPK), a cellular inhibitor of PKR, but does not change the expression and/or activity of other factors involved in the control of PKR activation. These findings delineate a novel mechanism by which Smad7 knockdown promotes CRC cell death.
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Warner MJ, Bridge KS, Hewitson JP, Hodgkinson MR, Heyam A, Massa BC, Haslam JC, Chatzifrangkeskou M, Evans GJO, Plevin MJ, Sharp TV, Lagos D. S6K2-mediated regulation of TRBP as a determinant of miRNA expression in human primary lymphatic endothelial cells. Nucleic Acids Res 2016; 44:9942-9955. [PMID: 27407113 PMCID: PMC5175334 DOI: 10.1093/nar/gkw631] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 06/16/2016] [Accepted: 07/02/2016] [Indexed: 12/13/2022] Open
Abstract
MicroRNAs (miRNAs) are short non-coding RNAs that silence mRNAs. They are generated following transcription and cleavage by the DROSHA/DGCR8 and DICER/TRBP/PACT complexes. Although it is known that components of the miRNA biogenesis machinery can be phosphorylated, it remains poorly understood how these events become engaged during physiological cellular activation. We demonstrate that S6 kinases can phosphorylate the extended C-terminal domain of TRBP and interact with TRBP in situ in primary cells. TRBP serines 283/286 are essential for S6K-mediated TRBP phosphorylation, optimal expression of TRBP, and the S6K-TRBP interaction in human primary cells. We demonstrate the functional relevance of this interaction in primary human dermal lymphatic endothelial cells (HDLECs). Angiopoietin-1 (ANG1) can augment miRNA biogenesis in HDLECs through enhancing TRBP phosphorylation and expression in an S6K2-dependent manner. We propose that the S6K2/TRBP node controls miRNA biogenesis in HDLECs and provides a molecular link between the mTOR pathway and the miRNA biogenesis machinery.
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Affiliation(s)
- Matthew J Warner
- Centre for Immunology and Infection, Department of Biology and Hull York Medical School, University of York, Wentworth Way, York, YO10 5DD, UK
| | - Katherine S Bridge
- Centre of Molecular Oncology, Barts Cancer Institute, John Vane Science Centre, Charterhouse Square, Queen Mary University London, London, EC1M 6BQ, UK
| | - James P Hewitson
- Centre for Immunology and Infection, Department of Biology and Hull York Medical School, University of York, Wentworth Way, York, YO10 5DD, UK
| | | | - Alex Heyam
- Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK
| | - Bailey C Massa
- Centre for Immunology and Infection, Department of Biology and Hull York Medical School, University of York, Wentworth Way, York, YO10 5DD, UK
| | - Jessica C Haslam
- Centre for Immunology and Infection, Department of Biology and Hull York Medical School, University of York, Wentworth Way, York, YO10 5DD, UK
| | - Maria Chatzifrangkeskou
- Centre for Immunology and Infection, Department of Biology and Hull York Medical School, University of York, Wentworth Way, York, YO10 5DD, UK
| | - Gareth J O Evans
- Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK
| | - Michael J Plevin
- Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK
| | - Tyson V Sharp
- Centre of Molecular Oncology, Barts Cancer Institute, John Vane Science Centre, Charterhouse Square, Queen Mary University London, London, EC1M 6BQ, UK
| | - Dimitris Lagos
- Centre for Immunology and Infection, Department of Biology and Hull York Medical School, University of York, Wentworth Way, York, YO10 5DD, UK
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Vaughn LS, Bragg DC, Sharma N, Camargos S, Cardoso F, Patel RC. Altered activation of protein kinase PKR and enhanced apoptosis in dystonia cells carrying a mutation in PKR activator protein PACT. J Biol Chem 2015; 290:22543-57. [PMID: 26231208 DOI: 10.1074/jbc.m115.669408] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Indexed: 12/21/2022] Open
Abstract
PACT is a stress-modulated activator of the interferon-induced double-stranded RNA-activated protein kinase (PKR). Stress-induced phosphorylation of PACT is essential for PACT's association with PKR leading to PKR activation. PKR activation leads to phosphorylation of translation initiation factor eIF2α inhibition of protein synthesis and apoptosis. A recessively inherited form of early-onset dystonia DYT16 has been recently identified to arise due to a homozygous missense mutation P222L in PACT. To examine if the mutant P222L protein alters the stress-response pathway, we examined the ability of mutant P222L to interact with and activate PKR. Our results indicate that the substitution mutant P222L activates PKR more robustly and for longer duration albeit with slower kinetics in response to the endoplasmic reticulum stress. In addition, the affinity of PACT-PACT and PACT-PKR interactions is enhanced in dystonia patient lymphoblasts, thereby leading to intensified PKR activation and enhanced cellular death. P222L mutation also changes the affinity of PACT-TRBP interaction after cellular stress, thereby offering a mechanism for the delayed PKR activation in response to stress. Our results demonstrate the impact of a dystonia-causing substitution mutation on stress-induced cellular apoptosis.
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Affiliation(s)
- Lauren S Vaughn
- From the University of South Carolina, Department of Biological Sciences, Columbia, South Carolina 29208
| | - D Cristopher Bragg
- Massachusetts General Hospital, Department of Neurology, Charlestown, Massachusetts 02129, and
| | - Nutan Sharma
- Massachusetts General Hospital, Department of Neurology, Charlestown, Massachusetts 02129, and
| | - Sarah Camargos
- Federal University of Minas Gerais, Department of Internal Medicine, 31270-901 Belo Horizonte, MG, Brazil
| | - Francisco Cardoso
- Federal University of Minas Gerais, Department of Internal Medicine, 31270-901 Belo Horizonte, MG, Brazil
| | - Rekha C Patel
- From the University of South Carolina, Department of Biological Sciences, Columbia, South Carolina 29208,
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26
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Heyam A, Lagos D, Plevin M. Dissecting the roles of TRBP and PACT in double-stranded RNA recognition and processing of noncoding RNAs. WILEY INTERDISCIPLINARY REVIEWS. RNA 2015; 6:271-89. [PMID: 25630541 PMCID: PMC7169789 DOI: 10.1002/wrna.1272] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 10/08/2014] [Accepted: 10/09/2014] [Indexed: 12/27/2022]
Abstract
HIV TAR RNA-binding protein (TRBP) and Protein Activator of PKR (PACT) are double-stranded (ds) RNA-binding proteins that participate in both small regulatory RNA biogenesis and the response to viral dsRNA. Despite considerable progress toward understanding the structure-function relationship of TRBP and PACT, their specific roles in these seemingly distinct cellular pathways remain unclear. Both proteins are composed of three copies of the double-stranded RNA-binding domain, two of which interact with dsRNA, while the C-terminal copy mediates protein-protein interactions. PACT and TRBP are found in a complex with the endonuclease Dicer and facilitate processing of immature microRNAs. Their precise contribution to the Dicing step has not yet been defined: possibilities include precursor recruitment, rearrangement of dsRNA within the complex, loading the processed microRNA into the RNA-induced silencing complex, and distinguishing different classes of small dsRNA. TRBP and PACT also interact with the viral dsRNA sensors retinoic acid-inducible gene I (RIG-I) and double-stranded RNA-activated protein kinase (PKR). Current models suggest that PACT enables RIG-I to detect a wider range of viral dsRNAs, while TRBP and PACT exert opposing regulatory effects on PKR. Here, the evidence that implicates TRBP and PACT in regulatory RNA processing and viral dsRNA sensing is reviewed and discussed in the context of their molecular structure. The broader implications of a link between microRNA biogenesis and the innate antiviral response pathway are also considered.
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MESH Headings
- Amino Acid Sequence
- Carboxypeptidases/chemistry
- Carboxypeptidases/metabolism
- Carboxypeptidases/physiology
- Models, Genetic
- Models, Molecular
- Molecular Sequence Data
- Protein Structure, Tertiary
- RNA, Double-Stranded/chemistry
- RNA, Double-Stranded/immunology
- RNA, Double-Stranded/metabolism
- RNA, Untranslated/metabolism
- RNA, Viral/chemistry
- RNA, Viral/immunology
- RNA, Viral/metabolism
- RNA-Binding Proteins/chemistry
- RNA-Binding Proteins/metabolism
- RNA-Binding Proteins/physiology
- Ribonuclease III/chemistry
- Ribonuclease III/metabolism
- Ribonuclease III/physiology
- Structure-Activity Relationship
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Affiliation(s)
- Alex Heyam
- Department of Biology, University of York, York, UK
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27
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Zech M, Castrop F, Schormair B, Jochim A, Wieland T, Gross N, Lichtner P, Peters A, Gieger C, Meitinger T, Strom TM, Oexle K, Haslinger B, Winkelmann J. DYT16 revisited: exome sequencing identifies PRKRA mutations in a European dystonia family. Mov Disord 2014; 29:1504-10. [PMID: 25142429 DOI: 10.1002/mds.25981] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 06/26/2014] [Accepted: 07/11/2014] [Indexed: 01/02/2023] Open
Abstract
Recessive DYT16 dystonia associated with mutations in PRKRA has until now been reported only in seven Brazilian patients. The aim of this study was to elucidate the genetic cause underlying disease in a Polish family with autosomal-recessive, early-onset generalized dystonia and slight parkinsonism, and to explore further the role of PRKRA in a dystonia series of European ancestry. We employed whole-exome sequencing in two affected siblings of the Polish family and filtered for rare homozygous and compound heterozygous variants shared by both exomes. Validation of the identified variants as well as homozygosity screening and copy number variation analysis was carried out in the two affected individuals and their healthy siblings. PRKRA was analyzed in 339 German patients with various forms of dystonia and 376 population-based controls by direct sequencing or high-resolution melting. The previously described homozygous p.Pro222Leu mutation in PRKRA was found to segregate with the disease in the studied family, contained in a 1.2 Mb homozygous region identical by state with all Brazilian patients in chromosome 2q31.2. The clinical presentation with young-onset, progressive generalized dystonia and mild parkinsonism resembled the phenotype of the original DYT16 cases. PRKRA mutational screening in additional dystonia samples revealed three novel heterozygous changes (p.Thr34Ser, p.Asn102Ser, c.-14A>G), each in a single subject with focal/segmental dystonia. Our study provides the first independent replication of the DYT16 locus at 2q31.2 and strongly confirms the causal contribution of the PRKRA gene to DYT16. Our data suggest worldwide involvement of PRKRA in dystonia.
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Affiliation(s)
- Michael Zech
- Neurologische Klinik und Poliklinik, Klinikum rechts der Isar, Technische Universität München, Munich, Germany; Institut für Humangenetik, Helmholtz Zentrum München, Munich, Germany
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28
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André ND, Silva VAO, Watanabe MAE, De Lucca FL. Intratumoral injection of PKR shRNA expressing plasmid inhibits B16-F10 melanoma growth. Oncol Rep 2014; 32:2267-73. [PMID: 25175769 DOI: 10.3892/or.2014.3410] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 08/04/2014] [Indexed: 11/06/2022] Open
Abstract
The RNA-dependent protein kinase (PKR) is a serine/threonine kinase that is involved in the regulation of important cell processes such as apoptosis, signal transduction, cell proliferation and differentiation. However, the role played by PKR in cancer remains controversial. RNA interference (RNAi) has currently become an important technique in understanding gene function. Previously, we showed that PKR shRNA downregulates PKR expression in B16-F10 melanoma cells and reduces the metastatic potential of these tumor cells. In the present study, we examined the effect of the intratumoral injection of PKR shRNA‑expressing plasmid on the growth of B16-F10 melanoma in mice. The results showed that this treatment significantly reduced tumor growth. Thus, these findings suggested that PKR acts as a tumor suppressor, a finding that is consistent with our previous study on the experimental model of metastasis. Moreover, the results suggested that this effect may be mediated by the transcription factor NF-κB. The present study confirmed the hypothesis that the direct administration of RNAi-based therapeutics in the target tumor is a promising approach for overcoming the obstacles of systemic delivery. The results also suggested that the intratumoral injection of PKR shRNA‑expressing vector is a novel therapeutic approach for human solid tumors such as cutaneous melanoma and breast cancer, since PKR is overexpressed in these tumors.
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Affiliation(s)
| | - Viviane Aline Oliveira Silva
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, 14049-900 Ribeirão Preto, SP, Brazil
| | - Maria Angelica Ehara Watanabe
- Department of Pathological Sciences, Biological Sciences Center, State University of Londrina, 86057-970 Londrina, PR, Brazil
| | - Fernando Luiz De Lucca
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, 14049-900 Ribeirão Preto, SP, Brazil
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29
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Yong Y, Luo J, Ke ZJ. dsRNA binding protein PACT/RAX in gene silencing, development and diseases. ACTA ACUST UNITED AC 2014; 9:382-388. [PMID: 25554729 DOI: 10.1007/s11515-014-1325-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
PACT (Protein kinase, interferon-inducible double stranded RNA dependent activator) and its murine ortholog RAX (PKR-associated protein X) were originally identified as a protein activator for the dsRNA-dependent, interferon-inducible protein kinase (PKR). Endogenous PACT/RAX activates PKR in response to diverse stress signals such as serum starvation, and peroxide or arsenite treatment. PACT/RAX heterodimerized with PKR and activated it with its third motif in the absence of dsRNA. The activation of PKR leads to enhanced eIF2α phosphorylation followed by apoptosis or inhibition of growth. Besides the role of activating PKR, PACT is associated with a ~500 kDa complex that contains Dicer, hAgo2, and TRBP (TAR RNA binding protein) and it associates with Dicer to facilitate the production of small interfering RNA. PACT/RAX plays an important role in diverse physiological and pathological processes. Pact-/- mice exhibit notable developmental abnormalities including microtia, with craniofacial ear, and hearing defects. Pact-/- mice had smaller body sizes and fertility defects, both of which were caused by defective pituitary functions. It was found that dRAX disrupted fly embryos homozygous, displayed highly abnormal commissural axon structure of the central nervous system, and 70% of the flies homozygous for the mutant allele died prior to adulthood. Using high density SNP genotyping arrays, it was found that a mutation in PRKRA (the PACT/RAX gene) is the causative genetic mutation in DYT16, a novel autosomal recessive dystonia-parkinsonism syndrome in Brazilian patients.
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Affiliation(s)
- Yue Yong
- Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Shanghai 200031, China
| | - Jia Luo
- Department of Pharmacology and Nutritional Sciences, University of Kentucky College of Medicine, Lexington, Kentucky 40536, USA
| | - Zun-Ji Ke
- Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Shanghai 200031, China ; Department of Biochemistry, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Shanghai 201203, China
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30
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Burugu S, Daher A, Meurs EF, Gatignol A. HIV-1 translation and its regulation by cellular factors PKR and PACT. Virus Res 2014; 193:65-77. [PMID: 25064266 DOI: 10.1016/j.virusres.2014.07.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 07/13/2014] [Accepted: 07/14/2014] [Indexed: 12/24/2022]
Abstract
The synthesis of proteins from viral mRNA is the first step towards viral assembly. Viruses are dependent upon the cellular translation machinery to synthesize their own proteins. The synthesis of proteins from the human immunodeficiency virus (HIV) type 1 and 2 RNAs utilize several alternative mechanisms. The regulation of viral protein production requires a constant interplay between viral requirements and the cell response to viral infection. Among the antiviral cell responses, the interferon-induced RNA activated protein kinase, PKR, regulates the cellular and viral translation. During HIV-1 infection, PKR activation is highly regulated by viral and cellular factors. The cellular TAR RNA Binding Protein, TRBP, the Adenosine Deaminase acting on RNA, ADAR1, and the PKR Activator, PACT, play important roles. Recent data show that PACT changes its function from activator to inhibitor in HIV-1 infected cells. Therefore, HIV-1 has evolved to replicate in cells in which TRBP, ADAR1 and PACT prevent PKR activation to allow efficient viral protein synthesis. This proper translation will initiate the assembly of viral particles.
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Affiliation(s)
- Samantha Burugu
- Virus-cell Interactions Laboratory, Lady Davis Institute for Medical Research, Montréal, QC, Canada; Department of Microbiology and Immunology, McGill University, Montréal, QC, Canada
| | - Aïcha Daher
- Virus-cell Interactions Laboratory, Lady Davis Institute for Medical Research, Montréal, QC, Canada
| | - Eliane F Meurs
- Institut Pasteur, Department of Virology, Hepacivirus and Innate Immunity Unit, Paris, France
| | - Anne Gatignol
- Virus-cell Interactions Laboratory, Lady Davis Institute for Medical Research, Montréal, QC, Canada; Department of Microbiology and Immunology, McGill University, Montréal, QC, Canada; Department of Medicine, Division of Experimental Medicine, McGill University, Montréal, QC, Canada.
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31
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Abstract
Antipsychotic drugs (APDs) can have a profound effect on the human body that extends well beyond our understanding of their neuropsychopharmacology. Some of these effects manifest themselves in peripheral blood lymphocytes, and in some cases, particularly in clozapine treatment, result in serious complications. To better understand the molecular biology of APD action in lymphocytes, we investigated the influence of chlorpromazine, haloperidol and clozapine in vitro, by microarray-based gene and microRNA (miRNA) expression analysis. JM-Jurkat T-lymphocytes were cultured in the presence of the APDs or vehicle alone over 2 wk to model the early effects of APDs on expression. Interestingly both haloperidol and clozapine appear to regulate the expression of a large number of genes. Functional analysis of APD-associated differential expression revealed changes in genes related to oxidative stress, metabolic disease and surprisingly also implicated pathways and biological processes associated with neurological disease consistent with current understanding of the activity of APDs. We also identified miRNA-mRNA interaction associated with metabolic pathways and cell death/survival, all which could have relevance to known side effects of APDs. These results indicate that APDs have a significant effect on expression in peripheral tissue that relate to both known mechanisms as well as poorly characterized side effects.
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32
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Marchal JA, Lopez GJ, Peran M, Comino A, Delgado JR, García-García JA, Conde V, Aranda FM, Rivas C, Esteban M, Garcia MA. The impact of PKR activation: from neurodegeneration to cancer. FASEB J 2014; 28:1965-74. [PMID: 24522206 DOI: 10.1096/fj.13-248294] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
An inverse association between cancer and neurodegeneration is plausible because these biological processes share several genes and signaling pathways. Whereas uncontrolled cell proliferation and decreased apoptotic cell death governs cancer, excessive apoptosis contributes to neurodegeneration. Protein kinase R (PKR), an interferon-inducible double-stranded RNA protein kinase, is involved in both diseases. PKR activation blocks global protein synthesis through eIF2α phosphorylation, leading to cell death in response to a variety of cellular stresses. However, PKR also has the dual role of activating the nuclear factor κ-B pathway, promoting cell proliferation. Whereas PKR is recognized for its negative effects on neurodegenerative diseases, in part, inducing high level of apoptosis, the role of PKR activation in cancer remains controversial. In general, PKR is considered to have a tumor suppressor function, and some clinical data show a correlation between suppressed or inactivated PKR and a poor prognosis for several cancers. However, other studies show high PKR expression and activation levels in various cancers, suggesting that PKR might contribute to neoplastic progression. Understanding the cellular factors and signals involved in the regulation of PKR in these age-related diseases is relevant and may have important clinical implications. The present review highlights the current knowledge on the role of PKR in neurodegeneration and cancer, with special emphasis on its regulation and clinical implications.
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Affiliation(s)
- Juan A Marchal
- 1University Hospital Virgen de las Nieves, Azpitarte sn., Granada E-18012, Spain.
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33
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Hu YS, Li W, Li DM, Liu Y, Fan LH, Rao ZC, Lin G, Hu CY. Cloning, expression and functional analysis of PKR from grass carp (Ctenopharyngodon idellus). FISH & SHELLFISH IMMUNOLOGY 2013; 35:1874-1881. [PMID: 24084043 DOI: 10.1016/j.fsi.2013.09.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2013] [Revised: 09/12/2013] [Accepted: 09/16/2013] [Indexed: 06/02/2023]
Abstract
The interferon-induced, dsRNA-activated protein kinase (PKR) is considered as an important component of innate immune system and as a representative effector protein of interferon system. In the present study, PKR gene (CiPKR, JX511974) from grass carp (Ctenopharyngodon idellus) was isolated and identified using homology-based PCR. CiPKR shares high sequence identity with the counterparts of goldfish (Crucian carp) and zebrafish (Danio rerio). The full-length cDNA of CiPKR was found to be 2436 bp, with an ORF of 2067 bp that encodes a polypeptide of 688 amino acids. The deduced polypeptide CiPKR contains three tandem dsRNA-binding motifs (dsRBMs) at the N-terminus and a conserved Ser/Thr kinase domain at the C-terminus. CiPKR was expressed ubiquitously at a low-level under normal conditions, but it could be up-regulated after intraperitoneal (ip) injection with grass carp haemorrhagic virus (GCHV). CiPKR was dramatically up-regulated at 6 h post-injection and then recovered rapidly to normal levels within 24 h; however, it was obviously up-regulated once again at 48 h or 72 h post-injection. It seemed that CiPKR could respond to GCHV infection in an IFN-independent as well as an IFN-dependent pathway. To further investigate its mechanism of biological actions, we constructed a series of recombinant plasmids including pcDNA3.1/PKR-wt, pcDNA3.1/PKR-K430R, pcDNA3.1/PKR-C (deletion of dsRBD sequence) and pcDNA3.1/PKR-C-K430R, and then each recombinant plasmid was transfected into CIK cells. In comparison with those of controls, a 79% and a 64% decrease of luciferase activities were detected in the tested cells transfected with CiPKR and CiPKR-C, respectively; however, luciferase activities were increased in those cells transfected with PKR-K430R and PKR-C-K430R, with a 160% and 115% up-regulation, respectively. Similarly, MTT colorimetric assay indicated that cell viabilities of CIK cells transfected with pcDNA3.1/PKR-wt, pcDNA3.1/PKR-K430R, pcDNA3.1/PKR-C and pcDNA3.1/PKR-C-K430R were 49%, 90%, 54% and 100%, respectively. Our observations suggested that the expression of CiPKR could be up-regulated following viral infection, and then resulted in the inhibition of protein synthesis and the induction of potential apoptosis.
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Affiliation(s)
- You-Sheng Hu
- Department of Bioscience, College of Life Science and Food Engineering, Nanchang University, Nanchang 330031, China; Medical College, Jinggangshan University, Ji'an 343009, China
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34
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Tronel C, Page G, Bodard S, Chalon S, Antier D. The specific PKR inhibitor C16 prevents apoptosis and IL-1β production in an acute excitotoxic rat model with a neuroinflammatory component. Neurochem Int 2013; 64:73-83. [PMID: 24211709 DOI: 10.1016/j.neuint.2013.10.012] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 10/10/2013] [Accepted: 10/22/2013] [Indexed: 12/20/2022]
Abstract
The double-stranded RNA-dependent protein kinase (PKR), an apoptotic inducer, regulates much pro-inflammatory cytokine production. The purpose of this study was to evaluate in vivo the effects of the specific PKR inhibitor C16 in the striatum in an acute excitotoxic rat model with an important neuroinflammatory component. Inflammation was induced by unilateral striatal injection of quinolinic acid (QA) in 10-week-old normotensive rats. Animals were separated into groups receiving either vehicle or C16 for both sham and QA rats. The effects were assessed in ipsi- and contralateral striata by immunoblotting for PKR activation, by Luminex assay for cytokine levels and by immunofluorescent staining for cleaved caspase-3 to detect neuronal apoptosis. The highest dose of C16 (600μg/kg; C16-2) in QA rats reduced expression of the active catalytic domain of the PKR vs. that in vehicle-injected QA rats. A robust increase of IL-1β levels on the contralateral side of QA rats was prevented by C16-2 (97% inhibition). Macroscopic and microscopic observation of cerebral tissue (Hematoxylin & Eosin staining) revealed that tissue integrity was more preserved with C16-2 treatment than its vehicle in QA rats. Furthermore, C16-2 treatment decreased by 47% the neuronal loss and by 37% the number of positive cleaved caspase-3 neurons induced by QA injection. In conclusion, C16 prevented not only the PKR-induced neuronal loss but also the inflammatory response in this acute excitotoxic in vivo model, highlighting its promising neuroprotective properties to rescue acute brain lesions.
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Affiliation(s)
- C Tronel
- INSERM U930, Tours, France; Université François Rabelais de Tours, UMR U930, Tours, France.
| | - G Page
- EA 3808, University of Poitiers, "Molecular Targets and Therapeutics of Alzheimer's Disease (CiMoTheMA)", 6 rue de la Milétrie, BP 199, 86034 Poitiers, France
| | - S Bodard
- INSERM U930, Tours, France; Université François Rabelais de Tours, UMR U930, Tours, France
| | - S Chalon
- INSERM U930, Tours, France; Université François Rabelais de Tours, UMR U930, Tours, France
| | - D Antier
- INSERM U930, Tours, France; Université François Rabelais de Tours, UMR U930, Tours, France
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35
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Clerzius G, Shaw E, Daher A, Burugu S, Gélinas JF, Ear T, Sinck L, Routy JP, Mouland AJ, Patel RC, Gatignol A. The PKR activator, PACT, becomes a PKR inhibitor during HIV-1 replication. Retrovirology 2013; 10:96. [PMID: 24020926 PMCID: PMC3848765 DOI: 10.1186/1742-4690-10-96] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Accepted: 09/06/2013] [Indexed: 11/29/2022] Open
Abstract
Background HIV-1 translation is modulated by the activation of the interferon (IFN)-inducible Protein Kinase RNA-activated (PKR). PKR phosphorylates its downstream targets, including the alpha subunit of the eukaryotic translation Initiation Factor 2 (eIF2α), which decreases viral replication. The PKR Activator (PACT) is known to activate PKR after a cellular stress. In lymphocytic cell lines, HIV-1 activates PKR only transiently and not when cells replicate the virus at high levels. The regulation of this activation is due to a combination of viral and cellular factors that have been only partially identified. Results PKR is transiently induced and activated in peripheral blood mononuclear cells after HIV-1 infection. The addition of IFN reduces viral replication, and induces both the production and phosphorylation of PKR. In lymphocytic Jurkat cells infected by HIV-1, a multiprotein complex around PKR contains the double-stranded RNA binding proteins (dsRBPs), adenosine deaminase acting on RNA (ADAR)1 and PACT. In HEK 293T cells transfected with an HIV-1 molecular clone, PACT unexpectedly inhibited PKR and eIF2α phosphorylation and increased HIV-1 protein expression and virion production in the presence of either endogenous PKR alone or overexpressed PKR. The comparison between different dsRBPs showed that ADAR1, TAR RNA Binding Protein (TRBP) and PACT inhibit PKR and eIF2α phosphorylation in HIV-infected cells, whereas Staufen1 did not. Individual or a combination of short hairpin RNAs against PACT or ADAR1 decreased HIV-1 protein expression. In the astrocytic cell line U251MG, which weakly expresses TRBP, PACT mediated an increased HIV-1 protein expression and a decreased PKR phosphorylation. In these cells, a truncated PACT, which constitutively activates PKR in non-infected cells showed no activity on either PKR or HIV-1 protein expression. Finally, PACT and ADAR1 interact with each other in the absence of RNAs. Conclusion In contrast to its previously described activity, PACT contributes to PKR dephosphorylation during HIV-1 replication. This activity is in addition to its heterodimer formation with TRBP and could be due to its binding to ADAR1. HIV-1 has evolved to replicate in cells with high levels of TRBP, to induce the expression of ADAR1 and to change the function of PACT for PKR inhibition and increased replication.
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Affiliation(s)
- Guerline Clerzius
- Lady Davis Institute for Medical Research, 3999 Côte Ste Catherine, Montréal, QC H3T 1E2, Canada.
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Casper C, Kalliolia E, Warner TT. Recent advances in the molecular pathogenesis of dystonia-plus syndromes and heredodegenerative dystonias. Curr Neuropharmacol 2013; 11:30-40. [PMID: 23814535 PMCID: PMC3580789 DOI: 10.2174/157015913804999432] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 08/17/2012] [Accepted: 08/29/2012] [Indexed: 12/04/2022] Open
Abstract
The majority of studies investigating the molecular pathogenesis and cell biology underlying dystonia have been performed in individuals with primary dystonia. This includes monogenic forms such as DYT1and DYT6 dystonia, and primary focal dystonia which is likely to be multifactorial in origin. In recent years there has been renewed interest in non-primary forms of dystonia including the dystonia-plus syndromes and heredodegenerative disorders. These are caused by a variety of genetic mutations and their study has contributed to our understanding of the neuronal dysfunction that leads to dystonia These findings have reinforced themes identified from study of primary dystonia including abnormal dopaminergic signalling, cellular trafficking and mitochondrial function. In this review we highlight recent advances in the understanding of the dystonia-plus syndromes and heredodegenerative dystonias.
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Affiliation(s)
- Catharina Casper
- Department of Clinical Neurosciences, UCL Institute of Neurology, Royal Free Campus, Rowland Hill Street, London NW3 2PF, United Kingdom
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