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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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Cottrell KA, Ryu S, Donelick H, Mai H, Pierce JR, Bass BL, Weber JD. Activation of PKR by a short-hairpin RNA. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.08.592371. [PMID: 38766230 PMCID: PMC11100704 DOI: 10.1101/2024.05.08.592371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Recognition of viral infection often relies on the detection of double-stranded RNA (dsRNA), a process that is conserved in many different organisms. In mammals, proteins such as MDA5, RIG-I, OAS, and PKR detect viral dsRNA, but struggle to differentiate between viral and endogenous dsRNA. This study investigates an shRNA targeting DDX54's potential to activate PKR, a key player in the immune response to dsRNA. Knockdown of DDX54 by a specific shRNA induced robust PKR activation in human cells, even when DDX54 is overexpressed, suggesting an off-target mechanism. Activation of PKR by the shRNA was enhanced by knockdown of ADAR1, a dsRNA binding protein that suppresses PKR activation, indicating a dsRNA-mediated mechanism. In vitro assays confirmed direct PKR activation by the shRNA. These findings emphasize the need for rigorous controls and alternative methods to validate gene function and minimize unintended immune pathway activation.
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Affiliation(s)
- Kyle A. Cottrell
- Department of Medicine, Division of Molecular Oncology, Washington University School of Medicine, Saint Louis, Missouri, USA
- ICCE Institute, Washington University School of Medicine, Saint Louis, Missouri, USA
- Department of Biochemistry, Purdue University, West Lafayette, IN, USA
| | - Sua Ryu
- Department of Medicine, Division of Molecular Oncology, Washington University School of Medicine, Saint Louis, Missouri, USA
- ICCE Institute, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Helen Donelick
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Hung Mai
- Department of Medicine, Division of Molecular Oncology, Washington University School of Medicine, Saint Louis, Missouri, USA
- ICCE Institute, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Jackson R. Pierce
- Department of Biochemistry, Purdue University, West Lafayette, IN, USA
| | - Brenda L. Bass
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Jason D. Weber
- Department of Medicine, Division of Molecular Oncology, Washington University School of Medicine, Saint Louis, Missouri, USA
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, Missouri, USA
- Department of Biology, Siteman Cancer Center, Washington University School of Medicine, Saint Louis, Missouri, USA
- ICCE Institute, Washington University School of Medicine, Saint Louis, Missouri, USA
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3
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Kim HJ, Han CW, Jeong MS, Jang SB. Cryo-EM structure of Influenza A virus NS1 and antiviral protein kinase PKR complex. Biochem Biophys Res Commun 2024; 706:149728. [PMID: 38479246 DOI: 10.1016/j.bbrc.2024.149728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2024] [Revised: 02/26/2024] [Accepted: 02/26/2024] [Indexed: 03/24/2024]
Abstract
Influenza A virus is the cause of a widespread human disease with high morbidity and mortality rates. The influenza virus encodes non-structural protein 1 (NS1), an exceedingly multifunctional virulence component. NS1 plays essential roles in viral replication and evasion of the cellular innate immune system. Protein kinase RNA-activated also known as protein kinase R (PKR) phosphorylates translation initiation factor eIF-2α on serine 51 to inhibit protein synthesis in virus-infected mammalian cells. Consequently, PKR activation inhibits mRNA translation, which results in the assert of both viral protein synthesis and cellular and possibly apoptosis in response to virus infection. Host signaling pathways are important in the replication of influenza virus, but the mechanisms involved remain to be characterized. Herein, the structure of NS1 and PKR complex was determined using Cryo-EM. We found the N91, E94, and G95 residues of PKR bind directly with N188, D125, and K126, respectively, of NS1. Furthermore, the study shows that PKR peptide offers a potential treatment for Influenza A virus infections.
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Affiliation(s)
- Hyeon Jin Kim
- Insitute of Systems Biology, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan, 46241, Republic of Korea
| | - Chang Woo Han
- Insitute of Systems Biology, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan, 46241, Republic of Korea
| | - Mi Suk Jeong
- Insitute of Systems Biology, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan, 46241, Republic of Korea.
| | - Se Bok Jang
- Insitute of Systems Biology, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan, 46241, Republic of Korea; Department of Molecular Biology, College of Natural Sciences, Pusan National University, 2, Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan, 46241, Republic of Korea.
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Solorio-Kirpichyan K, Fan X, Golovenko D, Korostelev AA, Yan N, Korennykh A. Cryo-EM Structure of HRSL Domain Reveals Activating Crossed Helices at the Core of GCN2. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.24.591037. [PMID: 38712127 PMCID: PMC11071503 DOI: 10.1101/2024.04.24.591037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
GCN2 is a conserved receptor kinase activating the Integrated Stress Response (ISR) in eukaryotic cells. The ISR kinases detect accumulation of stress molecules and reprogram translation from basal tasks to preferred production of cytoprotective proteins. GCN2 stands out evolutionarily among all protein kinases due to the presence of a h istidyl t R NA s ynthetase-like (HRSL) domain, which arises only in GCN2 and is located next to the kinase domain. How HRSL contributes to GCN2 signaling remains unknown. Here we report a 3.2 Å cryo-EM structure of HRSL from thermotolerant yeast Kluyveromyces marxianus . This structure shows a constitutive symmetrical homodimer featuring a compact helical-bundle structure at the junction between HRSL and kinase domains, in the core of the receptor. Mutagenesis demonstrates that this junction structure activates GCN2 and indicates that our cryo-EM structure captures the active signaling state of HRSL. Based on these results, we put forward a GCN2 regulation mechanism, where HRSL drives the formation of activated kinase dimers. Remaining domains of GCN2 have the opposite role and in the absence of stress they help keep GCN2 basally inactive. This autoinhibitory activity is relieved upon stress ligand binding. We propose that the opposing action of HRSL and additional GCN2 domains thus yields a regulated ISR receptor. Significance statement Regulation of protein synthesis (translation) is a central mechanism by which eukaryotic cells adapt to stressful conditions. In starving cells, this translational adaptation is achieved via the receptor kinase GCN2, which stays inactive under normal conditions, but is switched on under stress. The molecular mechanism of GCN2 switching is not well understood due to the presence of a structurally and biochemically uncharacterized h istidyl t R NA s ynthetase-like domain (HRSL) at the core of GCN2. Here we use single-particle cryo-EM and biochemistry to elucidate the structure and function of HRSL. We identify a structure at the kinase/HRSL interface, which forms crossed helices and helps position GCN2 kinase domains for activation. These data clarify the molecular mechanism of GCN2 regulation.
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Zhang R, Karijolich J. RNA recognition by PKR during DNA virus infection. J Med Virol 2024; 96:e29424. [PMID: 38285432 PMCID: PMC10832991 DOI: 10.1002/jmv.29424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Revised: 01/10/2024] [Accepted: 01/11/2024] [Indexed: 01/30/2024]
Abstract
Protein kinase R (PKR) is a double-stranded RNA (dsRNA) binding protein that plays a crucial role in innate immunity during viral infection and can restrict both DNA and RNA viruses. The potency of its antiviral function is further reflected by the large number of viral-encoded PKR antagonists. However, much about the regulation of dsRNA accumulation and PKR activation during viral infection remains unknown. Since DNA viruses do not have an RNA genome or RNA replication intermediates like RNA viruses do, PKR-mediated dsRNA detection in the context of DNA virus infection is particularly intriguing. Here, we review the current state of knowledge regarding the regulation of PKR activation and its antagonism during infection with DNA viruses.
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Affiliation(s)
- Ruilin Zhang
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232-2363, USA
- Vanderbilt Institute for Infection, Immunology and Inflammation, Vanderbilt Center for Immunobiology, Nashville. Nashville, TN 37232-2363, USA
| | - John Karijolich
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232-2363, USA
- Vanderbilt Institute for Infection, Immunology and Inflammation, Vanderbilt Center for Immunobiology, Nashville. Nashville, TN 37232-2363, USA
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6
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Wek RC, Anthony TG, Staschke KA. Surviving and Adapting to Stress: Translational Control and the Integrated Stress Response. Antioxid Redox Signal 2023; 39:351-373. [PMID: 36943285 PMCID: PMC10443206 DOI: 10.1089/ars.2022.0123] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 02/16/2023] [Accepted: 02/20/2023] [Indexed: 03/23/2023]
Abstract
Significance: Organisms adapt to changing environments by engaging cellular stress response pathways that serve to restore proteostasis and enhance survival. A primary adaptive mechanism is the integrated stress response (ISR), which features phosphorylation of the α subunit of eukaryotic translation initiation factor 2 (eIF2). Four eIF2α kinases respond to different stresses, enabling cells to rapidly control translation to optimize management of resources and reprogram gene expression for stress adaptation. Phosphorylation of eIF2 blocks its guanine nucleotide exchange factor, eIF2B, thus lowering the levels of eIF2 bound to GTP that is required to deliver initiator transfer RNA (tRNA) to ribosomes. While bulk messenger RNA (mRNA) translation can be sharply lowered by heightened phosphorylation of eIF2α, there are other gene transcripts whose translation is unchanged or preferentially translated. Among the preferentially translated genes is ATF4, which directs transcription of adaptive genes in the ISR. Recent Advances and Critical Issues: This review focuses on how eIF2α kinases function as first responders of stress, the mechanisms by which eIF2α phosphorylation and other stress signals regulate the exchange activity of eIF2B, and the processes by which the ISR triggers differential mRNA translation. To illustrate the synergy between stress pathways, we describe the mechanisms and functional significance of communication between the ISR and another key regulator of translation, mammalian/mechanistic target of rapamycin complex 1 (mTORC1), during acute and chronic amino acid insufficiency. Finally, we discuss the pathological conditions that stem from aberrant regulation of the ISR, as well as therapeutic strategies targeting the ISR to alleviate disease. Future Directions: Important topics for future ISR research are strategies for modulating this stress pathway in disease conditions and drug development, molecular processes for differential translation and the coordinate regulation of GCN2 and other stress pathways during physiological and pathological conditions. Antioxid. Redox Signal. 39, 351-373.
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Affiliation(s)
- Ronald C. Wek
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Indiana University Melvin and Bren Simon Comprehensive Cancer Center, Indianapolis, Indiana, USA
| | - Tracy G. Anthony
- Department of Nutritional Sciences, Rutgers University, New Brunswick, New Jersey, USA
| | - Kirk A. Staschke
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Indiana University Melvin and Bren Simon Comprehensive Cancer Center, Indianapolis, Indiana, USA
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Kim HJ, Han CW, Jeong MS, Jang SB. Structural study of novel vaccinia virus E3L and dsRNA-dependent protein kinase complex. Biochem Biophys Res Commun 2023; 665:1-9. [PMID: 37146409 DOI: 10.1016/j.bbrc.2023.04.107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 04/26/2023] [Accepted: 04/28/2023] [Indexed: 05/07/2023]
Abstract
E3L (RNA-binding protein E3) is one of the key IFN resistance genes encoded by VV and consists of 190 amino acids with a highly conserved carboxy-terminal double-stranded RNA-binding domain (dsRBD). PKR (dsRNA-dependent protein kinase) is an IFN-induced protein involved in anti-cell and antiviral activity. PKR inhibits the initiation of translation through alpha subunit of the initiation factor eIF2 (eIF2α) and mediates several transcription factors such as NF-κB, p53 or STATs. Activated PKR also induces apoptosis in vaccinia virus infection. E3L is required for viral IFN resistance and directly binds to PKR to block activation of PKR. In this work, we determined the three-dimensional complex structure of E3L and PKR using cryo-EM and determined the important residues involved in the interaction. In addition, PKR peptide binds to E3L and can increase protein levels of phosphorus-PKR and phosphorus-eIF2α-induced cell apoptosis through upregulation of phosphorus-PKR in HEK293 cells. Taken together, structural insights into E3L and PKR will provide a new optimization and development of vaccinia virus drugs.
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Affiliation(s)
- Hyeon Jin Kim
- Department of Molecular Biology, College of Natural Sciences, Pusan National University, 2, Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan, 46241, Republic of Korea
| | - Chang Woo Han
- Insitute of Systems Biology, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan, 46241, Republic of Korea
| | - Mi Suk Jeong
- Insitute for Plastic Information and Energy Materials and Sustainable Utilization of Photovoltaic Energy Research Center, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan, 46241, Republic of Korea; GJMEDI INC., Republic of Korea.
| | - Se Bok Jang
- Department of Molecular Biology, College of Natural Sciences, Pusan National University, 2, Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan, 46241, Republic of Korea; Insitute of Systems Biology, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan, 46241, Republic of Korea.
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8
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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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9
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Cusack KP, Argiriadi MA, Gordon TD, Harris CM, Herold JM, Hoemann MZ, Yestrepsky BD. Identification of potent and selective inhibitors of PKR via virtual screening and traditional design. Bioorg Med Chem Lett 2023; 79:129047. [PMID: 36400288 DOI: 10.1016/j.bmcl.2022.129047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 10/05/2022] [Accepted: 11/03/2022] [Indexed: 11/17/2022]
Abstract
Protein Kinase RNA-activated (PKR) inhibition is thought to be relevant for immunology due to the potential to reduce macrophage and dendritic cell responses to bacteria and its signaling downstream of TNFα. PKR is also associated with neuroscience indications such as Alzheimer's disease due to its activation by the double stranded DNA (dsDNA) virus HSV1, a virus suggested to be important in the development of AD. Studies exploring the mechanistic role of PKR with existing tool molecules such as the tricyclic oxindole C16 are clouded by the poor selectivity profile of this ATP-competitive, Type I kinase inhibitor. Type II kinase leads such as the benzothiophene or pyrazolopyrimidine scaffolds from literature are equally poor in their selectivity profiles. As such, it became necessary to identify more potent and selective chemical matter to better understand PKR biology. A dual approach was taken. The first step of the strategy included virtual screening of the AbbVie compound collection. A combination of pharmacophore-based and GPU shape-based screening was pursued to identify selective chemical matter from promiscuous leads. The second step of the strategy followed traditional compound design. This step initiated from a literature lead with PKR cross reactivity. Combined, the two parallel efforts led to identification of more selective leads for investigation of PKR biology.
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Affiliation(s)
- K P Cusack
- AbbVie Bioresearch Center, 381 Plantation Street, Worcester, MA 01605, United States.
| | - M A Argiriadi
- AbbVie Bioresearch Center, 381 Plantation Street, Worcester, MA 01605, United States
| | | | - C M Harris
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA 01605, United States
| | - J M Herold
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA 01605, United States
| | - M Z Hoemann
- AbbVie Bioresearch Center, 381 Plantation Street, Worcester, MA 01605, United States
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10
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Yang JH, Zhao Z, Niu W, Choi HP, Azadzoi KM. Formation of Double Stranded RNA Provokes Smooth Muscle Contractions and Structural Modifications in Bladder Ischemia. Res Rep Urol 2022; 14:399-414. [PMID: 36415310 PMCID: PMC9676006 DOI: 10.2147/rru.s388464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 11/11/2022] [Indexed: 08/30/2023] Open
Abstract
Purpose Growing evidence suggests that ischemia provokes detrusor overactivity and degenerative responses in the bladder. Underlying mechanisms appear to involve modification of smooth muscle contractile rudiments by hypoxia, redox, cellular stress and cell survival signaling. Downstream pathways of cellular stress and stress response molecules eliciting bladder dysfunction in ischemia remain largely elusive. Our goal was to define the role of double stranded RNA (dsRNA), a stress response molecule provoked by redox, in ischemia mediated bladder dysfunction. Methods A rat model of pelvic ischemia along with a cell culture hypoxia model were used to investigate the expression levels, functional consequences, structural aspects, and regulatory mechanisms of dsRNA in the bladder. Gene and protein expression were examined by reverse transcription polymerase chain reaction (RT-PCR), dot blot, and Western blotting, respectively. Tissue structure and function were assessed using histological staining and organ bath. Regulatory mechanisms were analyzed in cultured bladder smooth muscle cells. Results The data presented here provide the first evidence of the formation of dsRNA in the overactive bladder. dsRNA is a cellular stress response molecule that sensitizes smooth muscle and regulates inflammatory and degenerative rejoinders. Our data suggest that the production of dsRNA in the bladder is provoked by ischemia. Formation of dsRNA appears to augment bladder smooth muscle contractions and provoke fibrotic and apoptotic responses. Downstream actions of dsRNA in the bladder may involve upregulation of dsRNA-activated protein kinase R (PKR) and caspase-3, the executioner of apoptosis. Conclusion Activation of dsRNA/PKR pathway may play a role in sensitization of bladder smooth muscle cells to contractile stimuli, whereas dsRNA and caspase-3 crosstalk appear to modulate cellular stress and instigate degenerative responses in bladder ischemia. These observations suggest the role of dsRNA in bladder dysfunction and may open new perspectives to overcome overactive smooth muscle contractions and structural damage in the bladder.
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Affiliation(s)
- Jing-Hua Yang
- Department of Surgery, Boston University School of Medicine and Proteomics Laboratory, VA Boston Healthcare System, Boston, MA, USA
| | - Zuohui Zhao
- Department of Urology, Boston University School of Medicine, Boston, MA, USA
| | - Wanting Niu
- Research Department, VA Boston Healthcare System, Boston, MA, USA
| | - Han-Pil Choi
- Research Department, VA Boston Healthcare System, Boston, MA, USA
| | - Kazem M Azadzoi
- Departments of Urology and Pathology, VA Boston Healthcare System and Boston University School of Medicine, Boston, MA, USA
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11
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Nishikawa H, Christiany P, Hayashi T, Iizasa H, Yoshiyama H, Hatakeyama M. Kinase Activity of PAR1b, Which Mediates Nuclear Translocation of the BRCA1 Tumor Suppressor, Is Potentiated by Nucleic Acid-Mediated PAR1b Multimerization. Int J Mol Sci 2022; 23:6634. [PMID: 35743080 PMCID: PMC9223676 DOI: 10.3390/ijms23126634] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 06/09/2022] [Accepted: 06/12/2022] [Indexed: 02/07/2023] Open
Abstract
PAR1b is a cytoplasmic serine/threonine kinase that controls cell polarity and cell-cell interaction by regulating microtubule stability while mediating cytoplasmic-to-nuclear translocation of BRCA1. PAR1b is also a cellular target of the CagA protein of Helicobacter pylori, which leads to chronic infection causatively associated with the development of gastric cancer. The CagA-PAR1b interaction inactivates the kinase activity of PAR1b and thereby dampens PAR1b-mediated BRCA1 phosphorylation, which reduces the level of nuclear BRCA1 and thereby leads to BRCAness and BRCAness-associated genome instability underlying gastric carcinogenesis. While PAR1b can multimerize within the cells, little is known about the mechanism and functional role of PAR1b multimerization. We found in the present study that PAR1b was multimerized in vitro by binding with nucleic acids (both single- and double-stranded DNA/RNA) via the spacer region in a manner independent of nucleic-acid sequences, which markedly potentiated the kinase activity of PAR1b. Consistent with these in vitro observations, cytoplasmic introduction of double-stranded DNA or expression of single-stranded RNA increased the PAR1b kinase activity in the cells. These findings indicate that the cytoplasmic DNA/RNA contribute to nuclear accumulation of BRCA1 by constitutively activating/potentiating cytoplasmic PAR1b kinase activity, which is subverted in gastric epithelial cells upon delivery of H. pylori CagA oncoprotein.
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Affiliation(s)
- Hiroko Nishikawa
- Division of Microbiology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan; (H.N.); (P.C.); (T.H.)
| | - Priscillia Christiany
- Division of Microbiology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan; (H.N.); (P.C.); (T.H.)
| | - Takeru Hayashi
- Division of Microbiology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan; (H.N.); (P.C.); (T.H.)
| | - Hisashi Iizasa
- Department of Microbiology, Faculty of Medicine, Shimane University, Izumo 693-8501, Japan; (H.I.); (H.Y.)
| | - Hironori Yoshiyama
- Department of Microbiology, Faculty of Medicine, Shimane University, Izumo 693-8501, Japan; (H.I.); (H.Y.)
| | - Masanori Hatakeyama
- Division of Microbiology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan; (H.N.); (P.C.); (T.H.)
- Laboratory of Virology, Institute of Microbial Chemistry, Microbial Chemistry Research Foundation, Shinagawa-ku, Tokyo 141-0021, Japan
- Center for Infectious Cancers, Institute for Genetic Medicine, Hokkaido University, Kita-ku, Sapporo 060-0815, Japan
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12
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Li WX, Ding SW. Mammalian viral suppressors of RNA interference. Trends Biochem Sci 2022; 47:978-988. [PMID: 35618579 DOI: 10.1016/j.tibs.2022.05.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 04/14/2022] [Accepted: 05/02/2022] [Indexed: 12/18/2022]
Abstract
The antiviral defense directed by the RNAi pathway employs distinct specificity and effector mechanisms compared with other immune responses. The specificity of antiviral RNAi is programmed by siRNAs processed from virus-derived double-stranded RNA by Dicer endonuclease. Argonaute-containing RNA-induced silencing complex loaded with the viral siRNAs acts as the effector to mediate specific virus clearance by RNAi. Recent studies have provided evidence for the production and antiviral function of virus-derived siRNAs in both undifferentiated and differentiated mammalian cells infected with a range of RNA viruses when the cognate virus-encoded suppressor of RNAi (VSR) is rendered nonfunctional. In this review, we discuss the function, mechanism, and evolutionary origin of the validated mammalian VSRs and cell culture assays for their identification.
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Affiliation(s)
- Wan-Xiang Li
- Department of Microbiology and Plant Pathology, University of California, Riverside, Riverside, CA, USA
| | - Shou-Wei Ding
- Department of Microbiology and Plant Pathology, University of California, Riverside, Riverside, CA, USA.
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13
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Paithankar H, Tarang GS, Parvez F, Marathe A, Joshi M, Chugh J. Inherent conformational plasticity in dsRBDs enables interaction with topologically distinct RNAs. Biophys J 2022; 121:1038-1055. [PMID: 35134335 PMCID: PMC8943759 DOI: 10.1016/j.bpj.2022.02.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Revised: 12/25/2021] [Accepted: 02/03/2022] [Indexed: 11/02/2022] Open
Abstract
Many double-stranded RNA-binding domains (dsRBDs) interact with topologically distinct dsRNAs in biological pathways pivotal to viral replication, cancer causation, neurodegeneration, and so on. We hypothesized that the adaptability of dsRBDs is essential to target different dsRNA substrates. A model dsRBD and a few dsRNAs, slightly different in shape from each other, were used to test the systematic shape dependence of RNA on the dsRBD-binding using nuclear magnetic resonance (NMR) spectroscopy and molecular modeling. NMR-based titrations showed a distinct binding pattern for the dsRBD with the topologically distinct dsRNAs. The line broadening upon RNA binding was observed to cluster in the residues lying in close proximity, thereby suggesting an RNA-induced conformational exchange in the dsRBD. Further, while the intrinsic microsecond dynamics observed in the apo-dsRBD were found to quench upon binding with the dsRNA, the microsecond dynamics got induced at residues spatially proximal to quench sites upon binding with the dsRNA. This apparent relay of conformational exchange suggests the significance of intrinsic dynamics to help adapt the dsRBD to target various dsRNA-shapes. The conformational pool visualized in MD simulations for the apo-dsRBD reported here has also been observed to sample the conformations seen previously for various dsRBDs in apo- and in dsRNA-bound state structures, further suggesting the conformational adaptability of the dsRBDs. These investigations provide a dynamic basis for the substrate promiscuity for dsRBD proteins.
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Affiliation(s)
- Harshad Paithankar
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune, Maharashtra, India
| | - Guneet Singh Tarang
- Department of Biology, Indian Institute of Science Education and Research (IISER), Pune, Maharashtra, India
| | - Firdousi Parvez
- Department of Biology, Indian Institute of Science Education and Research (IISER), Pune, Maharashtra, India
| | - Aniket Marathe
- Bioinformatics Center, Savitrabai Phule Pune University, Pune, Maharashtra, India
| | - Manali Joshi
- Bioinformatics Center, Savitrabai Phule Pune University, Pune, Maharashtra, India
| | - Jeetender Chugh
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune, Maharashtra, India; Department of Biology, Indian Institute of Science Education and Research (IISER), Pune, Maharashtra, India.
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14
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Moradian H, Roch T, Anthofer L, Lendlein A, Gossen M. Chemical modification of uridine modulates mRNA-mediated proinflammatory and antiviral response in primary human macrophages. MOLECULAR THERAPY - NUCLEIC ACIDS 2022; 27:854-869. [PMID: 35141046 PMCID: PMC8807976 DOI: 10.1016/j.omtn.2022.01.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 01/07/2022] [Indexed: 12/12/2022]
Affiliation(s)
- Hanieh Moradian
- Institute of Active Polymers, Helmholtz-Zentrum Hereon, Kantstr. 55, 14513 Teltow, Germany
- Berlin-Brandenburg Center for Regenerative Therapies (BCRT), Föhrerstr. 15, 13353 Berlin, Germany
- Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Toralf Roch
- Berlin Institute of Health at Charité – Universitätsmedizin Berlin, BIH Center for Regenerative Therapies (BCRT), Charitéplatz 1, 10117 Berlin, Germany
- Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Center for Advanced Therapies, Augustenburger Platz 1, 13353 Berlin, Germany
- Center for Translational Medicine, Immunology, and Transplantation, Medical Department I, Marien Hospital Herne, University Hospital of the Ruhr-University Bochum, Hölkeskampring 40, 44625 Herne, Germany
| | - Larissa Anthofer
- Institute of Active Polymers, Helmholtz-Zentrum Hereon, Kantstr. 55, 14513 Teltow, Germany
- Berlin-Brandenburg Center for Regenerative Therapies (BCRT), Föhrerstr. 15, 13353 Berlin, Germany
| | - Andreas Lendlein
- Institute of Active Polymers, Helmholtz-Zentrum Hereon, Kantstr. 55, 14513 Teltow, Germany
- Berlin-Brandenburg Center for Regenerative Therapies (BCRT), Föhrerstr. 15, 13353 Berlin, Germany
- Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Manfred Gossen
- Institute of Active Polymers, Helmholtz-Zentrum Hereon, Kantstr. 55, 14513 Teltow, Germany
- Berlin-Brandenburg Center for Regenerative Therapies (BCRT), Föhrerstr. 15, 13353 Berlin, Germany
- Corresponding author Dr. Manfred Gossen, Institute of Active Polymers and Berlin-Brandenburg Center for Regenerative Therapies, Helmholtz-Zentrum Hereon, Kantstr. 55, 14513 Teltow, Germany.
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15
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Dutta N, Deb I, Sarzynska J, Lahiri A. Inosine and its methyl derivatives: Occurrence, biogenesis, and function in RNA. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2022; 169-170:21-52. [PMID: 35065168 DOI: 10.1016/j.pbiomolbio.2022.01.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 12/11/2021] [Accepted: 01/11/2022] [Indexed: 05/21/2023]
Abstract
Inosine is one of the most common post-transcriptional modifications. Since its discovery, it has been noted for its ability to contribute to non-Watson-Crick interactions within RNA. Rapidly accumulating evidence points to the widespread generation of inosine through hydrolytic deamination of adenosine to inosine by different classes of adenosine deaminases. Three naturally occurring methyl derivatives of inosine, i.e., 1-methylinosine, 2'-O-methylinosine and 1,2'-O-dimethylinosine are currently reported in RNA modification databases. These modifications are expected to lead to changes in the structure, folding, dynamics, stability and functions of RNA. The importance of the modifications is indicated by the strong conservation of the modifying enzymes across organisms. The structure, binding and catalytic mechanism of the adenosine deaminases have been well-studied, but the underlying mechanism of the catalytic reaction is not very clear yet. Here we extensively review the existing data on the occurrence, biogenesis and functions of inosine and its methyl derivatives in RNA. We also included the structural and thermodynamic aspects of these modifications in our review to provide a detailed and integrated discussion on the consequences of A-to-I editing in RNA and the contribution of different structural and thermodynamic studies in understanding its role in RNA. We also highlight the importance of further studies for a better understanding of the mechanisms of the different classes of deamination reactions. Further investigation of the structural and thermodynamic consequences and functions of these modifications in RNA should provide more useful information about their role in different diseases.
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Affiliation(s)
- Nivedita Dutta
- Department of Biophysics, Molecular Biology and Bioinformatics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata, 700009, West Bengal, India
| | - Indrajit Deb
- Department of Biophysics, Molecular Biology and Bioinformatics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata, 700009, West Bengal, India
| | - Joanna Sarzynska
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznan, Poland
| | - Ansuman Lahiri
- Department of Biophysics, Molecular Biology and Bioinformatics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata, 700009, West Bengal, India.
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16
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3dRNA: 3D structure prediction from linear to circular RNAs. J Mol Biol 2022; 434:167452. [DOI: 10.1016/j.jmb.2022.167452] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 01/07/2022] [Accepted: 01/07/2022] [Indexed: 12/30/2022]
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17
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Chen YG, Hur S. Cellular origins of dsRNA, their recognition and consequences. Nat Rev Mol Cell Biol 2021; 23:286-301. [PMID: 34815573 DOI: 10.1038/s41580-021-00430-1] [Citation(s) in RCA: 119] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/12/2021] [Indexed: 01/02/2023]
Abstract
Double-stranded RNA (dsRNA) is associated with most viral infections - it either constitutes the viral genome (in the case of dsRNA viruses) or is generated in host cells during viral replication. Hence, nearly all organisms have the capability of recognizing dsRNA and mounting a response, the primary aim of which is to mitigate the potential infection. In vertebrates, a set of innate immune receptors for dsRNA induce a multitude of cell-intrinsic and cell-extrinsic immune responses upon dsRNA recognition. Notably, recent studies showed that vertebrate cells can accumulate self-derived dsRNAs or dsRNA-like species upon dysregulation of several cellular processes, activating the very same immune pathways as in infected cells. On the one hand, such aberrant immune activation in the absence of infection can lead to pathogenesis of immune disorders, such as Aicardi-Goutières syndrome. On the other hand, the same innate immune reaction can be induced in a controlled setting for a therapeutic benefit, as occurs in immunotherapies. In this Review, we describe mechanisms by which immunostimulatory dsRNAs are generated in mammalian cells, either by viruses or by the host cells, and how cells respond to them, with the focus on recent developments regarding the role of cellular dsRNAs in immune modulation.
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Affiliation(s)
- Y Grace Chen
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT, USA.
| | - Sun Hur
- Harvard Medical School & Boston Children's Hospital, Boston, MA, USA.
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18
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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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19
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Yu H, Bruneau RC, Brennan G, Rothenburg S. Battle Royale: Innate Recognition of Poxviruses and Viral Immune Evasion. Biomedicines 2021; 9:biomedicines9070765. [PMID: 34356829 PMCID: PMC8301327 DOI: 10.3390/biomedicines9070765] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 06/25/2021] [Accepted: 06/26/2021] [Indexed: 12/17/2022] Open
Abstract
Host pattern recognition receptors (PRRs) sense pathogen-associated molecular patterns (PAMPs), which are molecular signatures shared by different pathogens. Recognition of PAMPs by PRRs initiate innate immune responses via diverse signaling pathways. Over recent decades, advances in our knowledge of innate immune sensing have enhanced our understanding of the host immune response to poxviruses. Multiple PRR families have been implicated in poxvirus detection, mediating the initiation of signaling cascades, activation of transcription factors, and, ultimately, the expression of antiviral effectors. To counteract the host immune defense, poxviruses have evolved a variety of immunomodulators that have diverse strategies to disrupt or circumvent host antiviral responses triggered by PRRs. These interactions influence the outcomes of poxvirus infections. This review focuses on our current knowledge of the roles of PRRs in the recognition of poxviruses, their elicited antiviral effector functions, and how poxviral immunomodulators antagonize PRR-mediated host immune responses.
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20
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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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21
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Lee HC, Fu CY, Lin CY, Hu JR, Huang TY, Lo KY, Tsai HY, Sheu JC, Tsai HJ. Poly(U)-specific endoribonuclease ENDOU promotes translation of human CHOP mRNA by releasing uORF element-mediated inhibition. EMBO J 2021; 40:e104123. [PMID: 33511665 PMCID: PMC8167367 DOI: 10.15252/embj.2019104123] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 11/18/2020] [Accepted: 11/30/2020] [Indexed: 12/24/2022] Open
Abstract
Upstream open reading frames (uORFs) are known to negatively affect translation of the downstream ORF. The regulatory proteins involved in relieving this inhibition are however poorly characterized. In response to cellular stress, eIF2α phosphorylation leads to an inhibition of global protein synthesis, while translation of specific factors such as CHOP is induced. We analyzed a 105‐nt inhibitory uORF in the transcript of human CHOP (huORFchop) and found that overexpression of the zebrafish or human ENDOU poly(U)‐endoribonuclease (Endouc or ENDOU‐1, respectively) increases CHOP mRNA translation also in the absence of stress. We also found that Endouc/ENDOU‐1 binds and cleaves the huORFchop transcript at position 80G‐81U, which induces CHOP translation independently of phosphorylated eIF2α. However, both ENDOU and phospho‐eIF2α are nonetheless required for maximal translation of CHOP mRNA. Increased levels of ENDOU shift a huORFchop reporter as well as endogenous CHOP transcripts from the monosome to polysome fraction, indicating an increase in translation. Furthermore, we found that the uncapped truncated huORFchop‐69‐105‐nt transcript contains an internal ribosome entry site (IRES), facilitating translation of the cleaved transcript. Therefore, we propose a model where ENDOU‐mediated transcript cleavage positively regulates CHOP translation resulting in increased CHOP protein levels upon stress. Specifically, CHOP transcript cleavage changes the configuration of huORFchop thereby releasing its inhibition and allowing the stalled ribosomes to resume translation of the downstream ORF.
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Affiliation(s)
- Hung-Chieh Lee
- Institute of Biomedical Sciences, Mackay Medical College, New Taipei City, Taiwan
| | - Chuan-Yang Fu
- Institute of Biomedical Sciences, Mackay Medical College, New Taipei City, Taiwan
| | - Cheng-Yung Lin
- Institute of Biomedical Sciences, Mackay Medical College, New Taipei City, Taiwan
| | - Jia-Rung Hu
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, Taiwan
| | - Ting-Ying Huang
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, Taiwan
| | - Kai-Yin Lo
- Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan
| | - Hsin-Yue Tsai
- Institute of Molecular Medicine, School of Medicine, National Taiwan University, Taipei, Taiwan
| | - Jin-Chuan Sheu
- Liver Disease Prevention and Treatment Research Foundation, Taipei, Taiwan
| | - Huai-Jen Tsai
- Institute of Biomedical Sciences, Mackay Medical College, New Taipei City, Taiwan.,Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, Taiwan.,Department of Life Science, Fu Jen Catholic University, New Taipei, Taiwan
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22
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Hesler S, Angeliadis M, Husain B, Cole JL. Contribution of dsRBD2 to PKR Activation. ACS OMEGA 2021; 6:11367-11374. [PMID: 34056292 PMCID: PMC8153938 DOI: 10.1021/acsomega.1c00343] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 04/02/2021] [Indexed: 06/12/2023]
Abstract
Protein kinase R (PKR) is a key pattern recognition receptor of the innate immune pathway. PKR is activated by double-stranded RNA (dsRNA) that is often produced during viral genome replication and transcription. PKR contains two tandem double-stranded RNA binding domains at the N-terminus, dsRBD1 and dsRBD2, and a C-terminal kinase domain. In the canonical model for activation, RNAs that bind multiple PKRs induce dimerization of the kinase domain that promotes an active conformation. However, there is evidence that dimerization of the kinase domain is not sufficient to mediate activation and PKR activation is modulated by the RNA-binding mode. dsRBD2 lacks most of the consensus RNA-binding residues, and it has been suggested to function as a modulator of PKR activation. Here, we demonstrate that dsRBD2 regulates PKR activation and identify the N-terminal helix as a critical region for modulating kinase activity. Mutations in dsRBD2 that have minor effects on overall dsRNA-binding affinity strongly inhibit the activation of PKR by dsRNA. These mutations also inhibit RNA-independent PKR activation. These data support a model where dsRBD2 has evolved to function as a regulator of the kinase.
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Affiliation(s)
- Stephen Hesler
- Department
of Molecular and Cell Biology, University
of Connecticut, Storrs 06269, Connecticut, United States
| | - Matthew Angeliadis
- Department
of Molecular and Cell Biology, University
of Connecticut, Storrs 06269, Connecticut, United States
| | - Bushra Husain
- Department
of Molecular and Cell Biology, University
of Connecticut, Storrs 06269, Connecticut, United States
| | - James L. Cole
- Department
of Molecular and Cell Biology, University
of Connecticut, Storrs 06269, Connecticut, United States
- Department
of Chemistry, University of Connecticut, Storrs 06269, Connecticut, United States
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23
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Cesaro T, Hayashi Y, Borghese F, Vertommen D, Wavreil F, Michiels T. PKR activity modulation by phosphomimetic mutations of serine residues located three aminoacids upstream of double-stranded RNA binding motifs. Sci Rep 2021; 11:9188. [PMID: 33911136 PMCID: PMC8080564 DOI: 10.1038/s41598-021-88610-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 04/12/2021] [Indexed: 11/28/2022] Open
Abstract
Eukaryotic translation initiation factor 2 alpha kinase 2 (EIF2AK2), better known as PKR, plays a key role in the response to viral infections and cellular homeostasis by regulating mRNA translation. Upon binding dsRNA, PKR is activated through homodimerization and subsequent autophosphorylation on residues Thr446 and Thr451. In this study, we identified a novel PKR phosphorylation site, Ser6, located 3 amino acids upstream of the first double-stranded RNA binding motif (DRBM1). Another Ser residue occurs in PKR at position 97, the very same position relative to the DRBM2. Ser or Thr residues also occur 3 amino acids upstream DRBMs of other proteins such as ADAR1 or DICER. Phosphoinhibiting mutations (Ser-to-Ala) introduced at Ser6 and Ser97 spontaneously activated PKR. In contrast, phosphomimetic mutations (Ser-to-Asp) inhibited PKR activation following either poly (I:C) transfection or virus infection. These mutations moderately affected dsRNA binding or dimerization, suggesting a model where negative charges occurring at position 6 and 97 tighten the interaction of DRBMs with the kinase domain, thus keeping PKR in an inactive closed conformation even in the presence of dsRNA. This study provides new insights on PKR regulation mechanisms and identifies Ser6 and Ser97 as potential targets to modulate PKR activity for therapeutic purposes.
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Affiliation(s)
- Teresa Cesaro
- de Duve Institute, Université Catholique de Louvain, VIRO B1.74.07, 74, Avenue Hippocrate, 1200, Brussels, Belgium
| | - Yohei Hayashi
- de Duve Institute, Université Catholique de Louvain, VIRO B1.74.07, 74, Avenue Hippocrate, 1200, Brussels, Belgium.,Frontier Sciences Unit, Department of Medical Innovations, Otsuka Pharmaceutical Co., Ltd., Tokushima, Japan
| | - Fabian Borghese
- de Duve Institute, Université Catholique de Louvain, VIRO B1.74.07, 74, Avenue Hippocrate, 1200, Brussels, Belgium
| | - Didier Vertommen
- PHOS Unit and MASSPROT Platform, de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
| | - Fanny Wavreil
- de Duve Institute, Université Catholique de Louvain, VIRO B1.74.07, 74, Avenue Hippocrate, 1200, Brussels, Belgium
| | - Thomas Michiels
- de Duve Institute, Université Catholique de Louvain, VIRO B1.74.07, 74, Avenue Hippocrate, 1200, Brussels, Belgium.
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24
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Zhao J, Qin C, Liu Y, Rao Y, Feng P. Herpes Simplex Virus and Pattern Recognition Receptors: An Arms Race. Front Immunol 2021; 11:613799. [PMID: 33584700 PMCID: PMC7878388 DOI: 10.3389/fimmu.2020.613799] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 12/14/2020] [Indexed: 12/25/2022] Open
Abstract
Herpes simplex viruses (HSVs) are experts in establishing persistent infection in immune-competent humans, in part by successfully evading immune activation through diverse strategies. Upon HSV infection, host deploys pattern recognition receptors (PRRs) to recognize various HSV-associated molecular patterns and mount antiviral innate immune responses. In this review, we describe recent advances in understanding the contributions of cytosolic PRRs to detect HSV and the direct manipulations on these receptors by HSV-encoded viral proteins as countermeasures. The continuous update and summarization of these mechanisms will deepen our understanding on HSV-host interactions in innate immunity for the development of novel antiviral therapies, vaccines and oncolytic viruses.
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Affiliation(s)
- Jun Zhao
- Section of Infection and Immunity, Herman Ostrow School of Dentistry, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA, United States
| | - Chao Qin
- Section of Infection and Immunity, Herman Ostrow School of Dentistry, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA, United States
| | - Yongzhen Liu
- Section of Infection and Immunity, Herman Ostrow School of Dentistry, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA, United States
| | - Youliang Rao
- Section of Infection and Immunity, Herman Ostrow School of Dentistry, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA, United States
| | - Pinghui Feng
- Section of Infection and Immunity, Herman Ostrow School of Dentistry, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA, United States
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25
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Erdmann EA, Mahapatra A, Mukherjee P, Yang B, Hundley HA. To protect and modify double-stranded RNA - the critical roles of ADARs in development, immunity and oncogenesis. Crit Rev Biochem Mol Biol 2020; 56:54-87. [PMID: 33356612 DOI: 10.1080/10409238.2020.1856768] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Adenosine deaminases that act on RNA (ADARs) are present in all animals and function to both bind double-stranded RNA (dsRNA) and catalyze the deamination of adenosine (A) to inosine (I). As inosine is a biological mimic of guanosine, deamination by ADARs changes the genetic information in the RNA sequence and is commonly referred to as RNA editing. Millions of A-to-I editing events have been reported for metazoan transcriptomes, indicating that RNA editing is a widespread mechanism used to generate molecular and phenotypic diversity. Loss of ADARs results in lethality in mice and behavioral phenotypes in worm and fly model systems. Furthermore, alterations in RNA editing occur in over 35 human pathologies, including several neurological disorders, metabolic diseases, and cancers. In this review, a basic introduction to ADAR structure and target recognition will be provided before summarizing how ADARs affect the fate of cellular RNAs and how researchers are using this knowledge to engineer ADARs for personalized medicine. In addition, we will highlight the important roles of ADARs and RNA editing in innate immunity and cancer biology.
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Affiliation(s)
- Emily A Erdmann
- Department of Biology, Indiana University, Bloomington, IN, USA
| | | | - Priyanka Mukherjee
- Medical Sciences Program, Indiana University School of Medicine-Bloomington, Bloomington, IN, USA
| | - Boyoon Yang
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
| | - Heather A Hundley
- Medical Sciences Program, Indiana University School of Medicine-Bloomington, Bloomington, IN, USA
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26
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Boussier J, Levi L, Weger-Lucarelli J, Poirier EZ, Vignuzzi M, Albert ML. Chikungunya virus superinfection exclusion is mediated by a block in viral replication and does not rely on non-structural protein 2. PLoS One 2020; 15:e0241592. [PMID: 33180795 PMCID: PMC7660575 DOI: 10.1371/journal.pone.0241592] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 10/16/2020] [Indexed: 01/20/2023] Open
Abstract
Superinfection exclusion (SIE) is a process by which a virally infected cell is protected from subsequent infection by the same or a closely related virus. By preventing cell coinfection, SIE favors preservation of genome integrity of a viral strain and limits its recombination potential with other viral genomes, thereby impacting viral evolution. Although described in virtually all viral families, the precise step(s) impacted by SIE during the viral life cycle have not been systematically explored. Here, we describe for the first time SIE triggered by chikungunya virus (CHIKV), an alphavirus of public health importance. Using single-cell technologies, we demonstrate that CHIKV excludes subsequent infection with: CHIKV; Sindbis virus, a related alphavirus; and influenza A, an unrelated RNA virus. We further demonstrate that SIE does not depend on the action of type I interferon, nor does it rely on host cell transcription. Moreover, exclusion is not mediated by the action of a single CHIKV protein; in particular, we observed no role for non-structural protein 2 (nsP2), making CHIKV unique among characterized alphaviruses. By stepping through the viral life cycle, we show that CHIKV exclusion occurs at the level of replication, but does not directly influence virus binding, nor viral structural protein translation. In sum, we characterized co-infection during CHIKV replication, which likely influences the rate of viral diversification and evolution.
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Affiliation(s)
- Jeremy Boussier
- Immubiology of Dendritic Cells unit, Institut Pasteur, Paris, France.,Inserm U1223, Institut Pasteur, Paris, France.,École doctorale Frontières du Vivant, Université Paris Diderot, Paris, France
| | - Laura Levi
- Viral Population and Pathogenesis Unit, Institut Pasteur, Paris, France
| | - James Weger-Lucarelli
- Viral Population and Pathogenesis Unit, Institut Pasteur, Paris, France.,Department of Biomedical Sciences and Pathobiology, Virginia Tech, VA-MD Regional College of Veterinary Medicine, Blacksburg, VA, United States of America
| | - Enzo Z Poirier
- Viral Population and Pathogenesis Unit, Institut Pasteur, Paris, France.,Immunobiology Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Marco Vignuzzi
- Viral Population and Pathogenesis Unit, Institut Pasteur, Paris, France
| | - Matthew L Albert
- Immubiology of Dendritic Cells unit, Institut Pasteur, Paris, France.,Insitro, South San Francisco, CA, United States of America
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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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28
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Asthana V, Stern BS, Tang Y, Bugga P, Li A, Ferguson A, Asthana A, Bao G, Drezek RA. Development of a Novel Class of Self-Assembling dsRNA Cancer Therapeutics: A Proof-of-Concept Investigation. MOLECULAR THERAPY-ONCOLYTICS 2020; 18:419-431. [PMID: 32913891 PMCID: PMC7452102 DOI: 10.1016/j.omto.2020.07.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Accepted: 07/28/2020] [Indexed: 10/26/2022]
Abstract
Cancer has proven to be an extremely difficult challenge to treat. Several fundamental issues currently underlie cancer treatment, including differentiating self from nonself, functional coupling of the recognition and therapeutic components of various therapies, and the propensity of cancerous cells to develop resistance to common treatment modalities via evolutionary pressure. Given these limitations, there is an increasing need to develop an all-encompassing therapeutic that can uniquely target malignant cells, decouple recognition from treatment, and overcome evolutionarily driven cancer resistance. We describe herein a new class of programmable self-assembling double-stranded RNA (dsRNA)-based cancer therapeutics that uniquely targets aberrant genetic sequences and in a functionally decoupled manner, undergoes oncogenic RNA-activated displacement (ORAD), initiating a therapeutic cascade that induces apoptosis and immune activation. As a proof of concept, we show that RNA strands targeting the EWS/Fli1 fusion gene in Ewing sarcoma cells that are end blocked with phosphorothioate bonds and additionally sealed with a 2'-deoxyuridine (2'-U)-modified DNA protector can be used to induce specific and potent killing of cells containing the target oncogenic sequence but not wild type.
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Affiliation(s)
| | - Brett S Stern
- Department of Bioengineering, Rice University, Houston, TX 77030, USA
| | - Yuqi Tang
- Department of Bioengineering, Rice University, Houston, TX 77030, USA
| | - Pallavi Bugga
- Department of Bioengineering, Rice University, Houston, TX 77030, USA
| | - Ang Li
- Department of Bioengineering, Rice University, Houston, TX 77030, USA
| | - Adam Ferguson
- Department of Bioengineering, Rice University, Houston, TX 77030, USA
| | - Anantratn Asthana
- Department of Bioengineering, Rice University, Houston, TX 77030, USA
| | - Gang Bao
- Department of Bioengineering, Rice University, Houston, TX 77030, USA
| | - Rebekah A Drezek
- Department of Bioengineering, Rice University, Houston, TX 77030, USA
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29
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Campbell LK, Magor KE. Pattern Recognition Receptor Signaling and Innate Responses to Influenza A Viruses in the Mallard Duck, Compared to Humans and Chickens. Front Cell Infect Microbiol 2020; 10:209. [PMID: 32477965 PMCID: PMC7236763 DOI: 10.3389/fcimb.2020.00209] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 04/16/2020] [Indexed: 12/25/2022] Open
Abstract
Mallard ducks are a natural host and reservoir of avian Influenza A viruses. While most influenza strains can replicate in mallards, the virus typically does not cause substantial disease in this host. Mallards are often resistant to disease caused by highly pathogenic avian influenza viruses, while the same strains can cause severe infection in humans, chickens, and even other species of ducks, resulting in systemic spread of the virus and even death. The differences in influenza detection and antiviral effectors responsible for limiting damage in the mallards are largely unknown. Domestic mallards have an early and robust innate response to infection that seems to limit replication and clear highly pathogenic strains. The regulation and timing of the response to influenza also seems to circumvent damage done by a prolonged or dysregulated immune response. Rapid initiation of innate immune responses depends on viral recognition by pattern recognition receptors (PRRs) expressed in tissues where the virus replicates. RIG-like receptors (RLRs), Toll-like receptors (TLRs), and Nod-like receptors (NLRs) are all important influenza sensors in mammals during infection. Ducks utilize many of the same PRRs to detect influenza, namely RIG-I, TLR7, and TLR3 and their downstream adaptors. Ducks also express many of the same signal transduction proteins including TBK1, TRIF, and TRAF3. Some antiviral effectors expressed downstream of these signaling pathways inhibit influenza replication in ducks. In this review, we summarize the recent advances in our understanding of influenza recognition and response through duck PRRs and their adaptors. We compare basal tissue expression and regulation of these signaling components in birds, to better understand what contributes to influenza resistance in the duck.
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Affiliation(s)
- Lee K Campbell
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.,Li Ka Shing Institute of Virology, University of Alberta, Edmonton, AB, Canada
| | - Katharine E Magor
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.,Li Ka Shing Institute of Virology, University of Alberta, Edmonton, AB, Canada
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30
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Shotwell CR, Cleary JD, Berglund JA. The potential of engineered eukaryotic RNA-binding proteins as molecular tools and therapeutics. WILEY INTERDISCIPLINARY REVIEWS-RNA 2019; 11:e1573. [PMID: 31680457 DOI: 10.1002/wrna.1573] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 09/21/2019] [Accepted: 10/08/2019] [Indexed: 02/06/2023]
Abstract
Eukaroytic RNA-binding proteins (RBPs) recognize and process RNAs through recognition of their sequence motifs via RNA-binding domains (RBDs). RBPs usually consist of one or more RBDs and can include additional functional domains that modify or cleave RNA. Engineered RBPs have been used to answer basic biology questions, control gene expression, locate viral RNA in vivo, as well as many other tasks. Given the growing number of diseases associated with RNA and RBPs, engineered RBPs also have the potential to serve as therapeutics. This review provides an in depth description of recent advances in engineered RBPs and discusses opportunities and challenges in the field. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Protein-RNA Recognition RNA Methods > RNA Nanotechnology RNA in Disease and Development > RNA in Disease.
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Affiliation(s)
- Carl R Shotwell
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida
| | - John D Cleary
- RNA Institute, University at Albany, Albany, New York
| | - J Andrew Berglund
- Department of Biological Sciences and RNA Institute, University at Albany, Albany, New York
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31
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Safran SA, Eckert DM, Leslie EA, Bass BL. PKR activation by noncanonical ligands: a 5'-triphosphate requirement versus antisense contamination. RNA (NEW YORK, N.Y.) 2019; 25:1192-1201. [PMID: 31239298 PMCID: PMC6800522 DOI: 10.1261/rna.071910.119] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 06/20/2019] [Indexed: 05/16/2023]
Abstract
Protein kinase RNA-activated (PKR) is an interferon-inducible kinase that is potently activated by long double-stranded RNA (dsRNA). In a previous study, we found that snoRNAs exhibit increased association with PKR in response to metabolic stress. While it was unclear if snoRNAs also activated PKR in cells, activation in vitro was observed. snoRNAs do not exhibit the double-stranded character typically required for activation of PKR, but some studies suggest such RNAs can activate PKR if triphosphorylated at the 5' terminus, or if they are able to form intermolecular dimers. To interrogate the mechanism of PKR activation by snoRNAs in vitro we focused on SNORD113. Using multiple methods for defining the 5'-phosphorylation state, we find that activation of PKR by SNORD113 does not require a 5'-triphosphate. Gel purification from a native gel followed by analysis using analytical ultracentrifugation showed that dimerization was also not responsible for activation. We isolated distinct conformers of SNORD113 from a native polyacrylamide gel and tracked the activating species to dsRNA formed from antisense RNA synthesized during in vitro transcription with T7 RNA polymerase. Similar studies with additional snoRNAs and small RNAs showed the generality of our results. Our studies suggest that a 5' triphosphate is not an activating ligand for PKR, and emphasize the insidious nature of antisense contamination.
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Affiliation(s)
- Sarah A Safran
- Department of Biochemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Debra M Eckert
- Department of Biochemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Evan A Leslie
- Department of Biochemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Brenda L Bass
- Department of Biochemistry, University of Utah, Salt Lake City, Utah 84112, USA
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32
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Mohibi S, Chen X, Zhang J. Cancer the'RBP'eutics-RNA-binding proteins as therapeutic targets for cancer. Pharmacol Ther 2019; 203:107390. [PMID: 31302171 DOI: 10.1016/j.pharmthera.2019.07.001] [Citation(s) in RCA: 119] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 07/02/2019] [Indexed: 12/11/2022]
Abstract
RNA-binding proteins (RBPs) play a critical role in the regulation of various RNA processes, including splicing, cleavage and polyadenylation, transport, translation and degradation of coding RNAs, non-coding RNAs and microRNAs. Recent studies indicate that RBPs not only play an instrumental role in normal cellular processes but have also emerged as major players in the development and spread of cancer. Herein, we review the current knowledge about RNA binding proteins and their role in tumorigenesis as well as the potential to target RBPs for cancer therapeutics.
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Affiliation(s)
- Shakur Mohibi
- Comparative Oncology Laboratory, Schools of Veterinary Medicine and Medicine, University of California at Davis, United States
| | - Xinbin Chen
- Comparative Oncology Laboratory, Schools of Veterinary Medicine and Medicine, University of California at Davis, United States
| | - Jin Zhang
- Comparative Oncology Laboratory, Schools of Veterinary Medicine and Medicine, University of California at Davis, United States.
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33
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Lee YS, Kunkeaw N, Lee YS. Protein kinase R and its cellular regulators in cancer: An active player or a surveillant? WILEY INTERDISCIPLINARY REVIEWS-RNA 2019; 11:e1558. [PMID: 31231984 DOI: 10.1002/wrna.1558] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 05/24/2019] [Accepted: 05/28/2019] [Indexed: 12/12/2022]
Abstract
Protein kinase R (PKR), originally known as an antiviral protein, senses various stresses as well as pathogen-driven double-stranded RNAs. Thereby activated PKR provokes diverse downstream events, including eIF2α phosphorylation and nuclear factor kappa-light-chain-enhancer of activated B cells activation. Consequently, PKR induces apoptosis and inflammation, both of which are highly important in cancer as much as its original antiviral role. Therefore, cellular proteins and RNAs should tightly control PKR activity. PKR and its regulators are often dysregulated in cancer and it is undoubted that such dysregulation contributes to tumorigenesis. However, PKR's precise role in cancer is still in debate, due to incomprehensible and even contradictory data. In this review, we introduce important cellular PKR regulators and discuss about their roles in cancer. Among them, we pay particular attention to nc886, a PKR repressor noncoding RNA that has been identified relatively recently, because its expression pattern in cancer can explain interesting yet obscure oncologic aspects of PKR. Based on nc886 and its regulation of PKR, we have proposed a tumor surveillance model, which reconciles contradictory data about PKR in cancer. This article is categorized under: Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.
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Affiliation(s)
- Yong Sun Lee
- Department of Cancer Biomedical Science, Graduate School of Cancer Science and Policy, National Cancer Center, Goyang, Korea
| | - Nawapol Kunkeaw
- Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, Thailand
| | - Yeon-Su Lee
- Division of Clinical Research, Research Institute, National Cancer Center, Goyang, Korea
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34
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Olejnik J, Hume AJ, Leung DW, Amarasinghe GK, Basler CF, Mühlberger E. Filovirus Strategies to Escape Antiviral Responses. Curr Top Microbiol Immunol 2019; 411:293-322. [PMID: 28685291 PMCID: PMC5973841 DOI: 10.1007/82_2017_13] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
This chapter describes the various strategies filoviruses use to escape host immune responses with a focus on innate immune and cell death pathways. Since filovirus replication can be efficiently blocked by interferon (IFN), filoviruses have evolved mechanisms to counteract both type I IFN induction and IFN response signaling pathways. Intriguingly, marburg- and ebolaviruses use different strategies to inhibit IFN signaling. This chapter also summarizes what is known about the role of IFN-stimulated genes (ISGs) in filovirus infection. These fall into three categories: those that restrict filovirus replication, those whose activation is inhibited by filoviruses, and those that have no measurable effect on viral replication. In addition to innate immunity, mammalian cells have evolved strategies to counter viral infections, including the induction of cell death and stress response pathways, and we summarize our current knowledge of how filoviruses interact with these pathways. Finally, this chapter delves into the interaction of EBOV with myeloid dendritic cells and macrophages and the associated inflammatory response, which differs dramatically between these cell types when they are infected with EBOV. In summary, we highlight the multifaceted nature of the host-viral interactions during filoviral infections.
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Affiliation(s)
- Judith Olejnik
- Department of Microbiology and National Emerging Infectious Diseases Laboratories, Boston University School of Medicine, 620 Albany Street, Boston, MA, 02118, USA
| | - Adam J Hume
- Department of Microbiology and National Emerging Infectious Diseases Laboratories, Boston University School of Medicine, 620 Albany Street, Boston, MA, 02118, USA
| | - Daisy W Leung
- Department of Pathology and Immunology, Washington University School of Medicine in St. Louis, St. Louis, MO, 63110, USA
| | - Gaya K Amarasinghe
- Department of Pathology and Immunology, Washington University School of Medicine in St. Louis, St. Louis, MO, 63110, USA
| | - Christopher F Basler
- Microbial Pathogenesis, Georgia State University, Institute for Biomedical Sciences, Atlanta, GA, 30303, USA
| | - Elke Mühlberger
- Department of Microbiology and National Emerging Infectious Diseases Laboratories, Boston University School of Medicine, 620 Albany Street, Boston, MA, 02118, USA.
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35
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Bou-Nader C, Gordon JM, Henderson FE, Zhang J. The search for a PKR code-differential regulation of protein kinase R activity by diverse RNA and protein regulators. RNA (NEW YORK, N.Y.) 2019; 25:539-556. [PMID: 30770398 PMCID: PMC6467004 DOI: 10.1261/rna.070169.118] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The interferon-inducible protein kinase R (PKR) is a key component of host innate immunity that restricts viral replication and propagation. As one of the four eIF2α kinases that sense diverse stresses and direct the integrated stress response (ISR) crucial for cell survival and proliferation, PKR's versatile roles extend well beyond antiviral defense. Targeted by numerous host and viral regulators made of RNA and proteins, PKR is subject to multiple layers of endogenous control and external manipulation, driving its rapid evolution. These versatile regulators include not only the canonical double-stranded RNA (dsRNA) that activates the kinase activity of PKR, but also highly structured viral, host, and artificial RNAs that exert a full spectrum of effects. In this review, we discuss our deepening understanding of the allosteric mechanism that connects the regulatory and effector domains of PKR, with an emphasis on diverse structured RNA regulators in comparison to their protein counterparts. Through this analysis, we conclude that much of the mechanistic details that underlie this RNA-regulated kinase await structural and functional elucidation, upon which we can then describe a "PKR code," a set of structural and chemical features of RNA that are both descriptive and predictive for their effects on PKR.
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Affiliation(s)
- Charles Bou-Nader
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA
| | - Jackson M Gordon
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA
| | - Frances E Henderson
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA
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36
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Pottash AE, Kuffner C, Noonan-Shueh M, Jay SM. Protein-based vehicles for biomimetic RNAi delivery. J Biol Eng 2019; 13:19. [PMID: 30891095 PMCID: PMC6390323 DOI: 10.1186/s13036-018-0130-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 12/09/2018] [Indexed: 12/30/2022] Open
Abstract
Broad translational success of RNA interference (RNAi) technology depends on the development of effective delivery approaches. To that end, researchers have developed a variety of strategies, including chemical modification of RNA, viral and non-viral transfection approaches, and incorporation with delivery vehicles such as polymer- and lipid-based nanoparticles, engineered and native proteins, extracellular vesicles (EVs), and others. Among these, EVs and protein-based vehicles stand out as biomimetically-inspired approaches, as both proteins (e.g. Apolipoprotein A-1, Argonaute 2, and Arc) and EVs mediate intercellular RNA transfer physiologically. Proteins specifically offer significant therapeutic potential due to their biophysical and biochemical properties as well as their ability to facilitate and tolerate manipulation; these characteristics have made proteins highly successful translational therapeutic molecules in the last two decades. This review covers engineered protein vehicles for RNAi delivery along with what is currently known about naturally-occurring extracellular RNA carriers towards uncovering design rules that will inform future engineering of protein-based vehicles.
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Affiliation(s)
- Alex Eli Pottash
- 1Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742 USA
| | - Christopher Kuffner
- 1Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742 USA
| | - Madeleine Noonan-Shueh
- 1Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742 USA
| | - Steven M Jay
- 1Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742 USA.,2Marlene and Stewart Greenebaum Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201 USA.,3Program in Molecular and Cellular Biology, University of Maryland, College Park, MD 20742 USA
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37
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Bober P, Tomková Z, Alexovič M, Ropovik I, Sabo J. The unfolded protein response controls endoplasmic reticulum stress-induced apoptosis of MCF-7 cells via a high dose of vitamin C treatment. Mol Biol Rep 2019; 46:1275-1284. [PMID: 30694453 DOI: 10.1007/s11033-019-04598-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 01/07/2019] [Indexed: 12/11/2022]
Abstract
Recent in vitro studies have shown that vitamin C (Vit C) with pro-oxidative properties causes cytotoxicity of breast cancer cells by selective oxidative stress. However, the effect of Vit C in itself at different concentration levels on MCF-7 breast cancer cell line after 24 h, has not yet been described. We aimed to examine the effect of Vit C on the viability and signalling response of MCF-7/WT (MCF-7 wild-type) cells that were exposed to various concentrations (0.125-4 mM) of Vit C during 24 h. The cytotoxic effect of Vit C on MCF-7/VitC (MCF-7/WT after added 2 mM Vit C) was observed, resulting in a decrease of cell index after 12 h. Also, the cytotoxicity of Vit C (2 mM) after 24 h was confirmed by flow cytometry, i.e., increase of dead, late apoptotic, and depolarized dead MCF-7/VitC cells compared to MCF-7/WT cells. Moreover, changes in proteomic profile of MCF-7/VitC cells compared to the control group were investigated via label-free quantitative mass spectrometry and post-translational modification. Using bioinformatics assessment (i.e., iPathwayGuide and SPIA R packages), a significantly impacted pathway in MCF-7/VitC was identified, namely the protein processing in endoplasmic reticulum. The semi-quantitative change (log2fold change = 4.5) and autophosphorylation at Thr-446 of protein kinase (PKR) (involved in this pathway) indicates that PKR protein could be responsible for the unfolded protein response and inhibition of the cell translation during endoplasmic reticulum stress, and eventually, for cell apoptosis. These results suggest that increased activity of PKR (Thr-446 autophosphorylation) related to cytotoxic effect of Vit C (2 mM) may cause the MCF-7 cells death.
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Affiliation(s)
- Peter Bober
- Department of Medical and Clinical Biophysics, Faculty of Medicine, University of P.J. Šafárik in Košice, Trieda SNP 1, 04011, Košice, Slovakia.
| | - Zuzana Tomková
- Department of Medical and Clinical Biophysics, Faculty of Medicine, University of P.J. Šafárik in Košice, Trieda SNP 1, 04011, Košice, Slovakia
| | - Michal Alexovič
- Department of Medical and Clinical Biophysics, Faculty of Medicine, University of P.J. Šafárik in Košice, Trieda SNP 1, 04011, Košice, Slovakia
| | - Ivan Ropovik
- Department of Pre-school and Elementary Education and Psychology, Faculty of Education, University of Presov, 17. novembra 15, 08001, Presov, Slovakia
| | - Ján Sabo
- Department of Medical and Clinical Biophysics, Faculty of Medicine, University of P.J. Šafárik in Košice, Trieda SNP 1, 04011, Košice, Slovakia
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38
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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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39
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Innate Immune Responses to Avian Influenza Viruses in Ducks and Chickens. Vet Sci 2019; 6:vetsci6010005. [PMID: 30634569 PMCID: PMC6466002 DOI: 10.3390/vetsci6010005] [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: 11/02/2018] [Revised: 12/26/2018] [Accepted: 01/04/2019] [Indexed: 02/06/2023] Open
Abstract
Mallard ducks are important natural hosts of low pathogenic avian influenza (LPAI) viruses and many strains circulate in this reservoir and cause little harm. Some strains can be transmitted to other hosts, including chickens, and cause respiratory and systemic disease. Rarely, these highly pathogenic avian influenza (HPAI) viruses cause disease in mallards, while chickens are highly susceptible. The long co-evolution of mallard ducks with influenza viruses has undoubtedly fine-tuned many immunological host–pathogen interactions to confer resistance to disease, which are poorly understood. Here, we compare innate responses to different avian influenza viruses in ducks and chickens to reveal differences that point to potential mechanisms of disease resistance. Mallard ducks are permissive to LPAI replication in their intestinal tissues without overtly compromising their fitness. In contrast, the mallard response to HPAI infection reflects an immediate and robust induction of type I interferon and antiviral interferon stimulated genes, highlighting the importance of the RIG-I pathway. Ducks also appear to limit the duration of the response, particularly of pro-inflammatory cytokine expression. Chickens lack RIG-I, and some modulators of the signaling pathway and may be compromised in initiating an early interferon response, allowing more viral replication and consequent damage. We review current knowledge about innate response mediators to influenza infection in mallard ducks compared to chickens to gain insight into protective immune responses, and open questions for future research.
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40
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Abou Elela S, Ji X. Structure and function of Rnt1p: An alternative to RNAi for targeted RNA degradation. WILEY INTERDISCIPLINARY REVIEWS-RNA 2018; 10:e1521. [PMID: 30548404 DOI: 10.1002/wrna.1521] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 10/30/2018] [Accepted: 11/15/2018] [Indexed: 12/27/2022]
Abstract
The double-stranded RNA-binding protein (dsRBP) family controls RNA editing, stability, and function in all eukaryotes. The central feature of this family is the recognition of a generic RNA duplex using highly conserved double-stranded RNA-binding domain (dsRBD) that recognizes the characteristic distance between the minor grooves created by the RNA helix. Variations on this theme that confer species and functional specificities have been reported but most dsRBPs retain their capacity to bind generic dsRNA. The ribonuclease III (RNase III) family members fall into four classes, represented by bacterial RNase III, yeast Rnt1p, human Drosha, and human Dicer, respectively. Like all dsRBPs and most members of the RNase III family, Rnt1p has a dsRBD, but unlike most of its kin, it poorly binds to generic RNA helices. Instead, Rnt1p, the only known RNase III expressed in Saccharomyces cerevisiae that lacks the RNAi (RNA interference) machinery, recognizes a specific class of stem-loop structures. To recognize the specific substrates, the dsRBD of Rnt1p is specialized, featuring a αβββααα topology and a sequence-specific RNA-binding motif at the C-terminus. Since the discovery of Rnt1p in 1996, significant progress has been made in studies of its genetics, function, structure, and mechanism of action, explaining the reasons and mechanisms for the increased specificity of this enzyme and its impact on the mechanism of RNA degradation. This article is categorized under: RNA Turnover and Surveillance > Turnover/Surveillance Mechanisms RNA Interactions with Proteins and Other Molecules > Protein-RNA Recognition RNA Processing > Processing of Small RNAs RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes.
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Affiliation(s)
- Sherif Abou Elela
- Microbiology and Infectiology Department, University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Xinhua Ji
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, Maryland
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41
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Faust O, Grunhaus D, Shimshon O, Yavin E, Friedler A. Protein Regulation by Intrinsically Disordered Regions: A Role for Subdomains in the IDR of the HIV-1 Rev Protein. Chembiochem 2018; 19:1618-1624. [PMID: 29791766 DOI: 10.1002/cbic.201800192] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2018] [Indexed: 11/06/2022]
Abstract
Intrinsically disordered regions (IDRs) in proteins are highly abundant, but they are still commonly viewed as long stretches of polar, solvent-accessible residues. Here we show that the disordered C-terminal domain (CTD) of HIV-1 Rev has two subregions that carry out two distinct complementary roles of regulating protein oligomerization and contributing to stability. We propose that this takes place through a delicate balance between charged and hydrophobic residues within the IDR. This means that mutations in this region, as well as the known mutations in the structured region of the protein, can affect protein function. We suggest that IDRs in proteins should be divided into subdomains similarly to structured regions, rather than being viewed as long flexible stretches.
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Affiliation(s)
- Ofrah Faust
- The Institute of Chemistry, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem, 91904, Israel
| | - Dana Grunhaus
- The Institute of Chemistry, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem, 91904, Israel
| | - Odelia Shimshon
- The School of Pharmacy, The Hebrew University of Jerusalem, Hadassah Ein Kerem, Jerusalem, 91120, Israel
| | - Eylon Yavin
- The School of Pharmacy, The Hebrew University of Jerusalem, Hadassah Ein Kerem, Jerusalem, 91120, Israel
| | - Assaf Friedler
- The Institute of Chemistry, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem, 91904, Israel
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42
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Melzer AM, Palanisamy N. Deleterious single nucleotide polymorphisms of protein kinase R identified by the computational approach. Mol Immunol 2018; 101:65-73. [PMID: 29879548 DOI: 10.1016/j.molimm.2018.05.026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 05/14/2018] [Accepted: 05/28/2018] [Indexed: 10/14/2022]
Abstract
The human protein kinase R (PKR) recognizes invading RNA viruses and mediates the antiviral immune response by phosphorylating the eukaryotic translation initiation factor 2α (eIF-2α), thus blocking protein translation in infected cells and thus preventing viral replication. The observation that individuals show different degrees of susceptibility to viral infections gives rise to the hypothesis that single nucleotide polymorphisms (SNPs) in the protein kinase R may alter the response to an infection. Using different available servers (e.g. SIFT, PROVEAN, Polyphen2, SNAP2, SNP&GOs, SNP-PhD, I-Mutant Suite), 14 SNPs were identified that were predicted to have deleterious effects on the protein kinase R. Five SNPs, namely D266Y, Y323D, I398 K, Y465C and Y472C, were selected for homology modeling and the generated models were investigated with regard to their secondary structure, residue fluctuations and eIF-2α binding. Analysis with computational tools POLYVIEW-MM, SAAPdap, SRIDE, CMView, elNémo, NMsim and PatchDock revealed structural changes in all mutants yielding a more stable structure at the cost of reduced flexibility (except Y465C) and less conformational freedom compared to the native protein. The conformational changes in the mutant protein structures and the displacement of functional residues from their strategic positions are predicted to affect the functionality of PKR, and consequently will affect the efficiency of the individual's antiviral immune response negatively. This study will aid the physicians in precision medicine field to tailor optimal treatment for the patients.
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Affiliation(s)
- Anna Maria Melzer
- Faculty of Biosciences, University of Heidelberg, Heidelberg, Germany
| | - Navaneethan Palanisamy
- Faculty of Biosciences, University of Heidelberg, Heidelberg, Germany; HBIGS, University of Heidelberg, Heidelberg, Germany; Institute of Biology II, University of Freiburg, Freiburg, Germany.
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43
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Dzananovic E, McKenna SA, Patel TR. Viral proteins targeting host protein kinase R to evade an innate immune response: a mini review. Biotechnol Genet Eng Rev 2018; 34:33-59. [PMID: 29716441 DOI: 10.1080/02648725.2018.1467151] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The innate immune system offers a first line of defense by neutralizing foreign pathogens such as bacteria, fungi, and viruses. These pathogens express molecules (RNA and proteins) that have discrete structures, known as the pathogen-associated molecular patterns that are recognized by a highly specialized class of host proteins called pattern recognition receptors to facilitate the host's immune response against infection. The RNA-dependent Protein Kinase R (PKR) is one of the host's pattern recognition receptors that is a key component of an innate immune system. PKR recognizes imperfectly double-stranded non-coding viral RNA molecules via its N-terminal double-stranded RNA binding motifs, undergoes phosphorylation of the C-terminal kinase domain, ultimately resulting in inhibition of viral protein translation by inhibiting the guanine nucleotide exchange activity of eukaryotic initiation factor 2α. Not surprisingly, viruses have evolved mechanisms by which viral non-coding RNA or protein molecules inhibit PKR's activation and/or its downstream activity to allow viral replication. In this review, we will highlight the role of viral proteins in inhibiting PKR's activity and summarize currently known mechanisms by which viral proteins execute such inhibitory activity.
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Affiliation(s)
- Edis Dzananovic
- a Plant Pathology, Plant Protection and Molecular Biology , Agriculture and Agri-Food Canada , Saskatoon , Canada
| | - Sean A McKenna
- b Department of Chemistry, Manitoba Institute for Materials, Department of Biochemistry and Medical Genetics , University of Manitoba , Winnipeg , Canada
| | - Trushar R Patel
- c Department of Chemistry and Biochemistry , Alberta RNA Research and Training Institute, University of Lethbridge , Lethbridge , Canada.,d DiscoveryLab, Faculty of Medicine & Dentistry , University of Alberta , Edmonton , Canada.,e Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine , University of Calgary , Calgary , Canada
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44
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Tai W, Li J, Corey E, Gao X. A ribonucleoprotein octamer for targeted siRNA delivery. Nat Biomed Eng 2018; 2:326-337. [PMID: 30936447 PMCID: PMC6136846 DOI: 10.1038/s41551-018-0214-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2017] [Accepted: 03/02/2018] [Indexed: 01/09/2023]
Abstract
Hurdles in cell-specific delivery of small interfering RNA (siRNA) in vivo hinder the clinical translation of RNA interference (RNAi). A fundamental problem concerns conflicting requirements for the design of the delivery vehicles: cationic materials facilitate cargo condensation and endosomolysis, yet hinder in vivo targeting and colloidal stability. Here, we describe a self-assembled, compact (~30 nm) and biocompatible ribonucleoprotein-octamer nanoparticle that achieves endosomal destabilization and targeted delivery. The protein octamer consists of a poly(ethylene glycol) scaffold, a sterically masked endosomolytic peptide and a double-stranded RNA-binding domain, providing a discrete number of siRNA loading sites and a high siRNA payload (>30 wt%), and offering flexibility in both siRNA and targeting-ligand selection. We show that a ribonucleoprotein octamer against the polo-like kinase 1 gene and bearing a ligand that binds to prostate-specific membrane antigen leads to efficient gene silencing in prostate tumour cells in vitro and when intravenously injected in mouse models of prostate cancer. The octamer's versatile nanocarrier design should offer opportunities for the clinical translation of therapies based on intracellularly acting biologics.
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Affiliation(s)
- Wanyi Tai
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Junwei Li
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Eva Corey
- Department of Urology, University of Washington, Seattle, WA, USA
| | - Xiaohu Gao
- Department of Bioengineering, University of Washington, Seattle, WA, USA.
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45
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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: 28] [Impact Index Per Article: 4.7] [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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46
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Heyam A, Coupland CE, Dégut C, Haley RA, Baxter NJ, Jakob L, Aguiar PM, Meister G, Williamson MP, Lagos D, Plevin MJ. Conserved asymmetry underpins homodimerization of Dicer-associated double-stranded RNA-binding proteins. Nucleic Acids Res 2017; 45:12577-12584. [PMID: 29045748 PMCID: PMC5716075 DOI: 10.1093/nar/gkx928] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 10/09/2017] [Indexed: 11/14/2022] Open
Abstract
Double-stranded RNA-binding domains (dsRBDs) are commonly found in modular proteins that interact with RNA. Two varieties of dsRBD exist: canonical Type A dsRBDs interact with dsRNA, while non-canonical Type B dsRBDs lack RNA-binding residues and instead interact with other proteins. In higher eukaryotes, the microRNA biogenesis enzyme Dicer forms a 1:1 association with a dsRNA-binding protein (dsRBP). Human Dicer associates with HIV TAR RNA-binding protein (TRBP) or protein activator of PKR (PACT), while Drosophila Dicer-1 associates with Loquacious (Loqs). In each case, the interaction involves a region of the protein that contains a Type B dsRBD. All three dsRBPs are reported to homodimerize, with the Dicer-binding region implicated in self-association. We report that these dsRBD homodimers display structural asymmetry and that this unusual self-association mechanism is conserved from flies to humans. We show that the core dsRBD is sufficient for homodimerization and that mutation of a conserved leucine residue abolishes self-association. We attribute differences in the self-association properties of Loqs, TRBP and PACT to divergence of the composition of the homodimerization interface. Modifications that make TRBP more like PACT enhance self-association. These data are examined in the context of miRNA biogenesis and the protein/protein interaction properties of Type B dsRBDs.
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Affiliation(s)
- Alex Heyam
- Department of Biology, University of York, York, YO10 5DD, UK
| | | | - Clément Dégut
- Department of Biology, University of York, York, YO10 5DD, UK
| | - Ruth A Haley
- Department of Biology, University of York, York, YO10 5DD, UK
| | - Nicola J Baxter
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, UK
| | - Leonhard Jakob
- Biochemistry Center Regensburg (BZR), Laboratory for RNA Biology, University of Regensburg, 93053 Regensburg, Germany
| | - Pedro M Aguiar
- Department of Chemistry, University of York, York, YO10 5DD, UK
| | - Gunter Meister
- Biochemistry Center Regensburg (BZR), Laboratory for RNA Biology, University of Regensburg, 93053 Regensburg, Germany
| | - Michael P Williamson
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, 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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47
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Tants JN, Fesser S, Kern T, Stehle R, Geerlof A, Wunderlich C, Juen M, Hartlmüller C, Böttcher R, Kunzelmann S, Lange O, Kreutz C, Förstemann K, Sattler M. Molecular basis for asymmetry sensing of siRNAs by the Drosophila Loqs-PD/Dcr-2 complex in RNA interference. Nucleic Acids Res 2017; 45:12536-12550. [PMID: 29040648 PMCID: PMC5716069 DOI: 10.1093/nar/gkx886] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 09/22/2017] [Accepted: 09/22/2017] [Indexed: 12/26/2022] Open
Abstract
RNA interference defends against RNA viruses and retro-elements within an organism's genome. It is triggered by duplex siRNAs, of which one strand is selected to confer sequence-specificity to the RNA induced silencing complex (RISC). In Drosophila, Dicer-2 (Dcr-2) and the double-stranded RNA binding domain (dsRBD) protein R2D2 form the RISC loading complex (RLC) and select one strand of exogenous siRNAs according to the relative thermodynamic stability of base-pairing at either end. Through genome editing we demonstrate that Loqs-PD, the Drosophila homolog of human TAR RNA binding protein (TRBP) and a paralog of R2D2, forms an alternative RLC with Dcr-2 that is required for strand choice of endogenous siRNAs in S2 cells. Two canonical dsRBDs in Loqs-PD bind to siRNAs with enhanced affinity compared to miRNA/miRNA* duplexes. Structural analysis, NMR and biophysical experiments indicate that the Loqs-PD dsRBDs can slide along the RNA duplex to the ends of the siRNA. A moderate but notable binding preference for the thermodynamically more stable siRNA end by Loqs-PD alone is greatly amplified in complex with Dcr-2 to initiate strand discrimination by asymmetry sensing in the RLC.
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Affiliation(s)
- Jan-Niklas Tants
- Institute of Structural Biology, Helmholtz Zentrum München, 85764 Neuherberg, Germany
- Center for Integrated Protein Science Munich at Chair of Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, 85748 Garching, Germany
| | - Stephanie Fesser
- Genzentrum & Department Biochemie, Ludwig-Maximilians-Universität, 81377 München, Germany
| | - Thomas Kern
- Institute of Structural Biology, Helmholtz Zentrum München, 85764 Neuherberg, Germany
- Center for Integrated Protein Science Munich at Chair of Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, 85748 Garching, Germany
| | - Ralf Stehle
- Institute of Structural Biology, Helmholtz Zentrum München, 85764 Neuherberg, Germany
- Center for Integrated Protein Science Munich at Chair of Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, 85748 Garching, Germany
| | - Arie Geerlof
- Institute of Structural Biology, Helmholtz Zentrum München, 85764 Neuherberg, Germany
| | - Christoph Wunderlich
- Institute of Organic Chemistry and Center for Molecular Biosciences CMBI, Universität Innsbruck, 6020 Innsbruck, Austria
| | - Michael Juen
- Institute of Organic Chemistry and Center for Molecular Biosciences CMBI, Universität Innsbruck, 6020 Innsbruck, Austria
| | - Christoph Hartlmüller
- Institute of Structural Biology, Helmholtz Zentrum München, 85764 Neuherberg, Germany
- Center for Integrated Protein Science Munich at Chair of Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, 85748 Garching, Germany
| | - Romy Böttcher
- Genzentrum & Department Biochemie, Ludwig-Maximilians-Universität, 81377 München, Germany
| | - Stefan Kunzelmann
- Genzentrum & Department Biochemie, Ludwig-Maximilians-Universität, 81377 München, Germany
| | - Oliver Lange
- Center for Integrated Protein Science Munich at Chair of Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, 85748 Garching, Germany
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences CMBI, Universität Innsbruck, 6020 Innsbruck, Austria
| | - Klaus Förstemann
- Genzentrum & Department Biochemie, Ludwig-Maximilians-Universität, 81377 München, Germany
| | - Michael Sattler
- Institute of Structural Biology, Helmholtz Zentrum München, 85764 Neuherberg, Germany
- Center for Integrated Protein Science Munich at Chair of Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, 85748 Garching, Germany
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48
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Impact of the structural integrity of the three-way junction of adenovirus VAI RNA on PKR inhibition. PLoS One 2017; 12:e0186849. [PMID: 29053745 PMCID: PMC5650172 DOI: 10.1371/journal.pone.0186849] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 10/09/2017] [Indexed: 02/06/2023] Open
Abstract
Highly structured RNA derived from viral genomes is a key cellular indicator of viral infection. In response, cells produce the interferon inducible RNA-dependent protein kinase (PKR) that, when bound to viral dsRNA, phosphorylates eukaryotic initiation factor 2α and attenuates viral protein translation. Adenovirus can evade this line of defence through transcription of a non-coding RNA, VAI, an inhibitor of PKR. VAI consists of three base-paired regions that meet at a three-way junction; an apical stem responsible for the interaction with PKR, a central stem required for inhibition, and a terminal stem. Recent studies have highlighted the potential importance of the tertiary structure of the three-way junction to PKR inhibition by enabling interaction between regions of the central and terminal stems. To further investigate the role of the three-way junction, we characterized the binding affinity and inhibitory potential of central stem mutants designed to introduce subtle alterations. These results were then correlated with small-angle X-ray scattering solution studies and computational tertiary structural models. Our results demonstrate that while mutations to the central stem have no observable effect on binding affinity to PKR, mutations that appear to disrupt the structure of the three-way junction prevent inhibition of PKR. Therefore, we propose that instead of simply sequestering PKR, a specific structural conformation of the PKR-VAI complex may be required for inhibition.
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49
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Vivarini ÁDC, Calegari-Silva TC, Saliba AM, Boaventura VS, França-Costa J, Khouri R, Dierckx T, Dias-Teixeira KL, Fasel N, Barral AMP, Borges VM, Van Weyenbergh J, Lopes UG. Systems Approach Reveals Nuclear Factor Erythroid 2-Related Factor 2/Protein Kinase R Crosstalk in Human Cutaneous Leishmaniasis. Front Immunol 2017; 8:1127. [PMID: 28959260 PMCID: PMC5605755 DOI: 10.3389/fimmu.2017.01127] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Accepted: 08/28/2017] [Indexed: 01/15/2023] Open
Abstract
Leishmania parasites infect macrophages, causing a wide spectrum of human diseases, from cutaneous to visceral forms. In search of novel therapeutic targets, we performed comprehensive in vitro and ex vivo mapping of the signaling pathways upstream and downstream of antioxidant transcription factor [nuclear factor erythroid 2-related factor 2 (Nrf2)] in cutaneous leishmaniasis (CL), by combining functional assays in human and murine macrophages with a systems biology analysis of in situ (skin biopsies) CL patient samples. First, we show the PKR pathway controls the expression and activation of Nrf2 in Leishmania amazonensis infection in vitro. Nrf2 activation also required PI3K/Akt signaling and autophagy mechanisms. Nrf2- or PKR/Akt-deficient macrophages exhibited increased levels of ROS/RNS and reduced expression of Sod1 Nrf2-dependent gene and reduced parasite load. L. amazonensis counteracted the Nrf2 inhibitor Keap1 through the upregulation of p62 via PKR. This Nrf2/Keap1 observation was confirmed in situ in skin biopsies from Leishmania-infected patients. Next, we explored the ex vivo transcriptome in CL patients, as compared to healthy controls. We found the antioxidant response element/Nrf2 signaling pathway was significantly upregulated in CL, including downstream target p62. In silico enrichment analysis confirmed upstream signaling by interferon and PI3K/Akt, and validated our in vitro findings. Our integrated in vitro, ex vivo, and in silico approach establish Nrf2 as a central player in human cutaneous leishmaniasis and reveal Nrf2/PKR crosstalk and PI3K/Akt pathways as potential therapeutic targets.
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Affiliation(s)
- Áislan de Carvalho Vivarini
- Laboratory of Molecular Parasitology, Carlos Chagas Filho Biophysics Institute, Center of Health Science, Federal University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Teresa Cristina Calegari-Silva
- Laboratory of Molecular Parasitology, Carlos Chagas Filho Biophysics Institute, Center of Health Science, Federal University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Alessandra Mattos Saliba
- Department of Microbiology, Immunology and Parasitology - FCM/UERJ, State University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Viviane Sampaio Boaventura
- Integrated Laboratory of Microbiology and Immunoregulation, Gonçalo Moniz Research Center, Oswaldo Cruz Foundation, Salvador, Bahia, Brazil
| | - Jaqueline França-Costa
- Integrated Laboratory of Microbiology and Immunoregulation, Gonçalo Moniz Research Center, Oswaldo Cruz Foundation, Salvador, Bahia, Brazil
| | - Ricardo Khouri
- Integrated Laboratory of Microbiology and Immunoregulation, Gonçalo Moniz Research Center, Oswaldo Cruz Foundation, Salvador, Bahia, Brazil
| | - Tim Dierckx
- Department of Microbiology and Immunology, Rega Institute for Medical Research, KU Leuven, Leuven, Belgium
| | - Karina Luiza Dias-Teixeira
- Laboratory of Molecular Parasitology, Carlos Chagas Filho Biophysics Institute, Center of Health Science, Federal University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Nicolas Fasel
- Faculty of Biology and Medicine, Department of Biochemistry, University of Lausanne, Lausanne, Switzerland
| | - Aldina Maria Prado Barral
- Integrated Laboratory of Microbiology and Immunoregulation, Gonçalo Moniz Research Center, Oswaldo Cruz Foundation, Salvador, Bahia, Brazil
| | - Valéria Matos Borges
- Integrated Laboratory of Microbiology and Immunoregulation, Gonçalo Moniz Research Center, Oswaldo Cruz Foundation, Salvador, Bahia, Brazil
| | - Johan Van Weyenbergh
- Department of Microbiology and Immunology, Rega Institute for Medical Research, KU Leuven, Leuven, Belgium
| | - Ulisses Gazos Lopes
- Laboratory of Molecular Parasitology, Carlos Chagas Filho Biophysics Institute, Center of Health Science, Federal University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
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50
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Abstract
Although the antiviral kinase PKR was originally characterized as a double-stranded RNA activated enzyme it can be stimulated by RNAs containing limited secondary structure. Single-stranded regions in such RNAs contribute to binding and activation but the mechanism is not understood. Here, we demonstrate that single-stranded RNAs bind to PKR with micromolar dissociation constants and can induce activation. Addition of a 5'-triphosphate slightly enhances binding affinity. Single-stranded RNAs also activate PKR constructs lacking the double-stranded RNA binding domain and bind to a basic region adjacent to the N-terminus of the kinase. However, the isolated kinase is not activated by and does not bind single-stranded RNA. Photocrosslinking measurements demonstrate that that the basic region interacts with RNA in the context of full length PKR. We propose that bivalent interactions with the double stranded RNA binding domain and the basic region underlie the ability of RNAs containing limited structure to activate PKR by enhancing binding affinity and thereby increasing the population of productive complexes containing two PKRs bound to a single RNA.
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