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Mikhalkevich N, O’Carroll IP, Tkavc R, Lund K, Sukumar G, Dalgard CL, Johnson KR, Li W, Wang T, Nath A, Iordanskiy S. Response of human macrophages to gamma radiation is mediated via expression of endogenous retroviruses. PLoS Pathog 2021; 17:e1009305. [PMID: 33556144 PMCID: PMC7895352 DOI: 10.1371/journal.ppat.1009305] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 02/19/2021] [Accepted: 01/11/2021] [Indexed: 01/11/2023] Open
Abstract
Ionizing radiation-induced tissue damage recruits monocytes into the exposed area where they are differentiated to macrophages. These implement phagocytic removal of dying cells and elicit an acute inflammatory response, but can also facilitate tumorigenesis due to production of anti-inflammatory cytokines. Using primary human monocyte-derived macrophages (MDMs) and the THP1 monocytic cell line, we demonstrate that gamma radiation triggers monocyte differentiation toward the macrophage phenotype with increased expression of type I interferons (IFN-I) and both pro- and anti-inflammatory macrophage activation markers. We found that these changes correlate with significantly upregulated expression of 622 retroelements from various groups, particularly of several clades of human endogenous retroviruses (HERVs). Elevated transcription was detected in both sense and antisense directions in the HERV subgroups tested, including the most genetically homogeneous clade HML-2. The level of antisense transcription was three- to five-fold higher than of the sense strand levels. Using a proximity ligation assay and immunoprecipitation followed by RNA quantification, we identified an increased amount of the dsRNA receptors MDA-5 and TLR3 bound to an equivalent number of copies of sense and antisense chains of HERVK HML-2 RNA. This binding triggered MAVS-associated signaling pathways resulting in increased expression of IFN-I and inflammation related genes that enhanced the cumulative inflammatory effect of radiation-induced senescence. HML-2 knockdown was accompanied with reduced expression and secretion of IFNα, pro-inflammatory (IL-1β, IL-6, CCL2, CCL3, CCL8, and CCL20) and anti-inflammatory (IL10) modulators in irradiated monocytes and MDMs. Taken together, our data indicate that radiation stress-induced HERV expression enhances the IFN-I and cytokine response and results in increased levels of pro-inflammatory modulators along with expression of anti-inflammatory factors associated with the macrophage tumorigenic phenotype. Ionizing radiation is a powerful stressogenic factor that induces massive cell damage. The signals released from radiation-damaged tissues recruit the monocytes, which are differentiated into macrophages that remove dying cells via phagocytosis and facilitate inflammation but can also contribute to tumorigenesis through anti-inflammatory and regenerative activities. The mechanism of this dual response of macrophages to irradiation is not fully understood. Using primary human macrophages and a monocytic cell line, we demonstrated that gamma radiation doses activate expression of various human endogenous retroviruses (HERVs). At the molecular level, we have shown that increased numbers of sense and antisense transcripts of tested HERV subgroups bind to double-stranded RNA receptors inducing the expression of type I interferons, multiple pro-inflammatory and some anti-inflammatory factors. At the phenotypic level, polarized macrophages exhibit a potent inflammatory response along with potentially tumorigenic characteristics. Our data suggest that endogenous retroviruses represent an important contributor of the macrophage-mediated inflammation in response to radiation-induced stress but may also indirectly influence tumorigenesis via biased macrophage polarization.
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Affiliation(s)
- Natallia Mikhalkevich
- Department of Pharmacology & Molecular Therapeutics, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - Ina P. O’Carroll
- Department of Chemistry, United States Naval Academy, Annapolis, Maryland, United States of America
| | - Rok Tkavc
- The Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland, United States of America
| | - Kateryna Lund
- Biomedical Instrumentation Center, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - Gauthaman Sukumar
- The American Genome Center (TAGC), Collaborative Health Initiative Research Program, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - Clifton L. Dalgard
- The American Genome Center (TAGC), Collaborative Health Initiative Research Program, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
- Department of Anatomy, Physiology & Genetics, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - Kory R. Johnson
- Bioinformatics Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Wenxue Li
- Section of Infections of the Nervous System, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Tongguang Wang
- Section of Infections of the Nervous System, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Avindra Nath
- Section of Infections of the Nervous System, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail: (AN); (SI)
| | - Sergey Iordanskiy
- Department of Pharmacology & Molecular Therapeutics, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
- * E-mail: (AN); (SI)
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Abstract
Reverse transcription is an obligatory step in retrovirus replication in the course of which the retroviral RNA/DNA-dependent DNA polymerase (RT) copies the single-stranded positive sense RNA genome to synthesize the double-stranded viral DNA. At the same time the RT-associated RNaseH activity degrades the genomic RNA template, which has just been copied. The viral nucleocapsid protein NCp7 is an obligatory partner of RT, chaperoning synthesis of the complete viral DNA flanked by the two long-terminal repeats (LTR), required for viral DNA integration into the host genome and its expression. Here we describe assays for in vitro and ex vivo monitoring of reverse transcription and the chaperoning role of the nucleocapsid protein (NC).
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Grigorov B, Bocquin A, Gabus C, Avilov S, Mély Y, Agopian A, Divita G, Gottikh M, Witvrouw M, Darlix JL. Identification of a methylated oligoribonucleotide as a potent inhibitor of HIV-1 reverse transcription complex. Nucleic Acids Res 2011; 39:5586-96. [PMID: 21447560 PMCID: PMC3141241 DOI: 10.1093/nar/gkr117] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Upon HIV-1 infection of a target cell, the viral reverse transcriptase (RT) copies the genomic RNA to synthesize the viral DNA. The genomic RNA is within the incoming HIV-1 core where it is coated by molecules of nucleocapsid (NC) protein that chaperones the reverse transcription process. Indeed, the RT chaperoning properties of NC extend from the initiation of cDNA synthesis to completion of the viral DNA. New and effective drugs against HIV-1 continue to be required, which prompted us to search for compounds aimed at inhibiting NC protein. Here, we report that the NC chaperoning activity is extensively inhibited in vitro by small methylated oligoribonucleotides (mODN). These mODNs were delivered intracellularly using a cell-penetrating-peptide and found to impede HIV-1 replication in primary human cells at nanomolar concentrations. Extensive analysis showed that viral cDNA synthesis was severely impaired by mODNs. Partially resistant viruses with mutations in NC and RT emerged after months of passaging in cell culture. A HIV-1 molecular clone (NL4.3) bearing these mutations was found to replicate at high concentrations of mODN, albeit with a reduced fitness. Small, methylated ODNs such as mODN-11 appear to be a new type of highly potent inhibitor of HIV-1.
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Affiliation(s)
- Boyan Grigorov
- Laboretro, INSERM #758, ENS Lyon, 46 allée d'Italie, 69364 Lyon, Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasboug, Illkirch, France
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Iordanskiy S, Waltke M, Feng Y, Wood C. Subtype-associated differences in HIV-1 reverse transcription affect the viral replication. Retrovirology 2010; 7:85. [PMID: 20939905 PMCID: PMC2964588 DOI: 10.1186/1742-4690-7-85] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Accepted: 10/12/2010] [Indexed: 01/08/2023] Open
Abstract
Background The impact of the products of the pol gene, specifically, reverse transcriptase (RT) on HIV-1 replication, evolution, and acquisition of drug resistance has been thoroughly characterized for subtype B. For subtype C, which accounts of almost 60% of HIV cases worldwide, much less is known. It has been reported that subtype C HIV-1 isolates have a lower replication capacity than B; however, the basis of these differences remains unclear. Results We analyzed the impact of the pol gene products from HIV-1 B and C subtypes on the maturation of HIV virions, accumulation of reverse transcription products, integration of viral DNA, frequency of point mutations in provirus and overall viral replication. Recombinant HIV-1 viruses of B and C subtypes comprising the pol fragments encoding protease, integrase and either the whole RT or a chimeric RT from different isolates of the C and B subtypes, were used for infection of cells expressing CXCR4 or CCR5 co-receptors. The viruses carrying different fragments of pol from the isolates of B and C subtypes did not reveal differences in Gag and GagPol processing and viral RNA incorporation into the virions. However, the presence of the whole RT from subtype C, or the chimeric RT containing either the polymerase or the connection and RNase H domains from C isolates, caused significantly slower viral replication regardless of B or C viral backbone. Subtype C RT carrying viruses displayed lower levels of accumulation of strong-stop cDNA in permeabilized virions during endogenous reverse transcription, and decreased accumulation of both strong-stop and positive strand reverse transcription products in infected cells and in isolated reverse transcription complexes. This decreased accumulation correlated with lower levels of viral DNA integration in cells infected with viruses carrying the whole RT or RT domains from subtype C isolates. The single viral genome assay analysis did not reveal significant differences in the frequency of point mutations between the RT from B or C subtypes. Conclusions These data suggest that the whole RT as well as distinct polymerase and connection-RNase H domains from subtype C HIV-1 confer a lower level of accumulation of reverse transcripts in the virions and reverse transcription complexes as compared to subtype B, resulting in a lower overall level of virus replication.
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Affiliation(s)
- Sergey Iordanskiy
- Nebraska Center for Virology, School of Biological Sciences, University of Nebraska-Lincoln, 4240 Fair Street, East Campus, Lincoln, NE 68583-0900 USA.
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Mougel M, Cimarelli A, Darlix JL. Implications of the nucleocapsid and the microenvironment in retroviral reverse transcription. Viruses 2010; 2:939-960. [PMID: 21994662 PMCID: PMC3185662 DOI: 10.3390/v2040939] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Revised: 03/03/2010] [Accepted: 04/01/2010] [Indexed: 01/21/2023] Open
Abstract
This mini-review summarizes the process of reverse-transcription, an obligatory step in retrovirus replication during which the retroviral RNA/DNA-dependent DNA polymerase (RT) copies the single-stranded genomic RNA to generate the double-stranded viral DNA while degrading the genomic RNA via its associated RNase H activity. The hybridization of complementary viral sequences by the nucleocapsid protein (NC) receives a special focus, since it acts to chaperone the strand transfers obligatory for synthesis of the complete viral DNA and flanking long terminal repeats (LTR). Since the physiological microenvironment can impact on reverse-transcription, this mini-review also focuses on factors present in the intra-cellular or extra-cellular milieu that can drastically influence both the timing and the activity of reverse-transcription and hence virus infectivity.
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Affiliation(s)
- Marylène Mougel
- CPBS, UMR5236 CNRS, UMI, 4 bd Henri IV, 34965 Montpellier, France; E-Mail:
| | - Andrea Cimarelli
- LaboRetro Unité de Virologie humaine INSERM #758, IFR128, ENS Lyon, 46 Allée d’Italie, 69364 Lyon, France; E-Mail:
| | - Jean-Luc Darlix
- LaboRetro Unité de Virologie humaine INSERM #758, IFR128, ENS Lyon, 46 Allée d’Italie, 69364 Lyon, France; E-Mail:
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +33 472728169; Fax: +33 472728137
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