1
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Banchenko S, Krupp F, Gotthold C, Bürger J, Graziadei A, O’Reilly FJ, Sinn L, Ruda O, Rappsilber J, Spahn CMT, Mielke T, Taylor IA, Schwefel D. Structural insights into Cullin4-RING ubiquitin ligase remodelling by Vpr from simian immunodeficiency viruses. PLoS Pathog 2021; 17:e1009775. [PMID: 34339457 PMCID: PMC8360603 DOI: 10.1371/journal.ppat.1009775] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 08/12/2021] [Accepted: 07/02/2021] [Indexed: 12/21/2022] Open
Abstract
Viruses have evolved means to manipulate the host's ubiquitin-proteasome system, in order to down-regulate antiviral host factors. The Vpx/Vpr family of lentiviral accessory proteins usurp the substrate receptor DCAF1 of host Cullin4-RING ligases (CRL4), a family of modular ubiquitin ligases involved in DNA replication, DNA repair and cell cycle regulation. CRL4DCAF1 specificity modulation by Vpx and Vpr from certain simian immunodeficiency viruses (SIV) leads to recruitment, poly-ubiquitylation and subsequent proteasomal degradation of the host restriction factor SAMHD1, resulting in enhanced virus replication in differentiated cells. To unravel the mechanism of SIV Vpr-induced SAMHD1 ubiquitylation, we conducted integrative biochemical and structural analyses of the Vpr protein from SIVs infecting Cercopithecus cephus (SIVmus). X-ray crystallography reveals commonalities between SIVmus Vpr and other members of the Vpx/Vpr family with regard to DCAF1 interaction, while cryo-electron microscopy and cross-linking mass spectrometry highlight a divergent molecular mechanism of SAMHD1 recruitment. In addition, these studies demonstrate how SIVmus Vpr exploits the dynamic architecture of the multi-subunit CRL4DCAF1 assembly to optimise SAMHD1 ubiquitylation. Together, the present work provides detailed molecular insight into variability and species-specificity of the evolutionary arms race between host SAMHD1 restriction and lentiviral counteraction through Vpx/Vpr proteins.
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Affiliation(s)
- Sofia Banchenko
- Charité–Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Berlin, Germany
| | - Ferdinand Krupp
- Charité–Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Berlin, Germany
| | - Christine Gotthold
- Charité–Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Berlin, Germany
| | - Jörg Bürger
- Charité–Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Berlin, Germany
- Microscopy and Cryo-Electron Microscopy Service Group, Max-Planck-Institute for Molecular Genetics, Berlin, Germany
| | - Andrea Graziadei
- Bioanalytics Unit, Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany
| | - Francis J. O’Reilly
- Bioanalytics Unit, Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany
| | - Ludwig Sinn
- Bioanalytics Unit, Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany
| | - Olga Ruda
- Charité–Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Berlin, Germany
| | - Juri Rappsilber
- Bioanalytics Unit, Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany
- Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Christian M. T. Spahn
- Charité–Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Berlin, Germany
| | - Thorsten Mielke
- Microscopy and Cryo-Electron Microscopy Service Group, Max-Planck-Institute for Molecular Genetics, Berlin, Germany
| | - Ian A. Taylor
- Macromolecular Structure Laboratory, The Francis Crick Institute, London, United Kingdom
| | - David Schwefel
- Charité–Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Berlin, Germany
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2
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Wang C, Meng L, Wang J, Zhang K, Duan S, Ren P, Wei Y, Fu X, Yu B, Wu J, Yu X. Role of Intracellular Distribution of Feline and Bovine SAMHD1 Proteins in Lentiviral Restriction. Virol Sin 2021; 36:981-996. [PMID: 33751400 DOI: 10.1007/s12250-021-00351-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 12/28/2020] [Indexed: 11/28/2022] Open
Abstract
Human SAMHD1 (hSAM) restricts lentiviruses at the reverse transcription step through its dNTP triphosphohydrolase (dNTPase) activity. Besides humans, several mammalian species such as cats and cows that carry their own lentiviruses also express SAMHD1. However, the intracellular distribution of feline and bovine SAMHD1 (fSAM and bSAM) and its significance in their lentiviral restriction function is not known. Here, we demonstrated that fSAM and bSAM were both predominantly localized to the nucleus and nuclear localization signal (11KRPR14)-deleted fSAM and bSAM relocalized to the cytoplasm. Both cytoplasmic fSAM and bSAM retained the antiviral function against different lentiviruses and cytoplasmic fSAM could restrict Vpx-encoding SIV and HIV-2 more efficiently than its wild-type (WT) protein as cytoplasmic hSAM. Further investigation revealed that cytoplasmic fSAM was resistant to Vpx-induced degradation like cytoplasmic hSAM, while cytoplasmic bSAM was not, but they all demonstrated the same in vitro dNTPase activity and all could interact with Vpx as their WT proteins, indicating that cytoplasmic hSAM and fSAM can suppress more SIV and HIV-2 by being less sensitive to Vpx-mediated degradation. Our results suggested that fSAM- and bSAM-mediated lentiviral restriction does not require their nuclear localization and that fSAM shares more common features with hSAM. These findings may provide insights for the establishment of alternative animal models to study SAMHD1 in vivo.
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Affiliation(s)
- Chu Wang
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China.,The First Hospital and Institute of Immunology, Jilin University, Changchun, 130012, China
| | - Lina Meng
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China
| | - Jialin Wang
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China
| | - Kaikai Zhang
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China
| | - Sizhu Duan
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China
| | - Pengyu Ren
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China
| | - Yingzhe Wei
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China
| | - Xinyu Fu
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China
| | - Bin Yu
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China.,Key Laboratory for Molecular Enzymology and Engineering, the Ministry of Education, School of Life Sciences, Jilin University, Changchun, 130012, China
| | - Jiaxin Wu
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China. .,Key Laboratory for Molecular Enzymology and Engineering, the Ministry of Education, School of Life Sciences, Jilin University, Changchun, 130012, China.
| | - Xianghui Yu
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China. .,Key Laboratory for Molecular Enzymology and Engineering, the Ministry of Education, School of Life Sciences, Jilin University, Changchun, 130012, China.
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3
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Cingöz O, Arnow ND, Puig Torrents M, Bannert N. Vpx enhances innate immune responses independently of SAMHD1 during HIV-1 infection. Retrovirology 2021; 18:4. [PMID: 33563288 PMCID: PMC7871410 DOI: 10.1186/s12977-021-00548-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 01/25/2021] [Accepted: 01/29/2021] [Indexed: 11/10/2022] Open
Abstract
Background The genomes of HIV-2 and some SIV strains contain the accessory gene vpx, which carries out several functions during infection, including the downregulation of SAMHD1. Vpx is also commonly used in experiments to increase HIV-1 infection efficiency in myeloid cells, particularly in studies that investigate the activation of antiviral pathways. However, the potential effects of Vpx on cellular innate immune signaling is not completely understood. We investigated whether and how Vpx affects ISG responses in monocytic cell lines and MDMs during HIV-1 infection. Results HIV-1 infection at excessively high virus doses can induce ISG activation, although at the expense of high levels of cell death. At equal infection levels, the ISG response is potentiated by the presence of Vpx and requires the initiation of reverse transcription. The interaction of Vpx with the DCAF1 adaptor protein is important for the enhanced response, implicating Vpx-mediated degradation of a host factor. Cells lacking SAMHD1 show similarly augmented responses, suggesting an effect that is independent of SAMHD1 degradation. Overcoming SAMHD1 restriction in MDMs to reach equal infection levels with viruses containing and lacking Vpx reveals a novel function of Vpx in elevating innate immune responses. Conclusions Vpx likely has as yet undefined roles in infected cells. Our results demonstrate that Vpx enhances ISG responses in myeloid cell lines and primary cells independently of its ability to degrade SAMHD1. These findings have implications for innate immunity studies in myeloid cells that use Vpx delivery with HIV-1 infection.
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Affiliation(s)
- Oya Cingöz
- Department of Infectious Diseases HIV and Other Retroviruses, Robert Koch Institute, Berlin, Germany.
| | - Nicolas D Arnow
- Department of Infectious Diseases HIV and Other Retroviruses, Robert Koch Institute, Berlin, Germany
| | - Mireia Puig Torrents
- Department of Infectious Diseases HIV and Other Retroviruses, Robert Koch Institute, Berlin, Germany
| | - Norbert Bannert
- Department of Infectious Diseases HIV and Other Retroviruses, Robert Koch Institute, Berlin, Germany
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4
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Zhang F, Bieniasz PD. HIV-1 Vpr induces cell cycle arrest and enhances viral gene expression by depleting CCDC137. eLife 2020; 9:55806. [PMID: 32538781 PMCID: PMC7295576 DOI: 10.7554/elife.55806] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 05/05/2020] [Indexed: 12/22/2022] Open
Abstract
The HIV-1 Vpr accessory protein induces ubiquitin/proteasome-dependent degradation of many cellular proteins by recruiting them to a cullin4A-DDB1-DCAF1 complex. In so doing, Vpr enhances HIV-1 gene expression and induces (G2/M) cell cycle arrest. However, the identities of Vpr target proteins through which these biological effects are exerted are unknown. We show that a chromosome periphery protein, CCDC137/cPERP-B, is targeted for depletion by HIV-1 Vpr, in a cullin4A-DDB1-DCAF1 dependent manner. CCDC137 depletion caused G2/M cellcycle arrest, while Vpr-resistant CCDC137 mutants conferred resistance to Vpr-induced G2/M arrest. CCDC137 depletion also recapitulated the ability of Vpr to enhance HIV-1 gene expression, particularly in macrophages. Our findings indicate that Vpr promotes cell-cycle arrest and HIV-1 gene expression through depletion of CCDC137.
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Affiliation(s)
- Fengwen Zhang
- Laboratory of Retrovirology, The Rockefeller University, New York, United States
| | - Paul D Bieniasz
- Laboratory of Retrovirology, The Rockefeller University, New York, United States.,Howard Hughes Medical Institute, The Rockefeller University, New York, United States
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5
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Vpr and Its Cellular Interaction Partners: R We There Yet? Cells 2019; 8:cells8111310. [PMID: 31652959 PMCID: PMC6912716 DOI: 10.3390/cells8111310] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 10/22/2019] [Accepted: 10/23/2019] [Indexed: 12/17/2022] Open
Abstract
Vpr is a lentiviral accessory protein that is expressed late during the infection cycle and is packaged in significant quantities into virus particles through a specific interaction with the P6 domain of the viral Gag precursor. Characterization of the physiologically relevant function(s) of Vpr has been hampered by the fact that in many cell lines, deletion of Vpr does not significantly affect viral fitness. However, Vpr is critical for virus replication in primary macrophages and for viral pathogenesis in vivo. It is generally accepted that Vpr does not have a specific enzymatic activity but functions as a molecular adapter to modulate viral or cellular processes for the benefit of the virus. Indeed, many Vpr interacting factors have been described by now, and the goal of this review is to summarize our current knowledge of cellular proteins targeted by Vpr.
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6
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Monit C, Morris ER, Ruis C, Szafran B, Thiltgen G, Tsai MHC, Mitchison NA, Bishop KN, Stoye JP, Taylor IA, Fassati A, Goldstein RA. Positive selection in dNTPase SAMHD1 throughout mammalian evolution. Proc Natl Acad Sci U S A 2019; 116:18647-18654. [PMID: 31451672 PMCID: PMC6744909 DOI: 10.1073/pnas.1908755116] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The vertebrate protein SAMHD1 is highly unusual in having roles in cellular metabolic regulation, antiviral restriction, and regulation of innate immunity. Its deoxynucleoside triphosphohydrolase activity regulates cellular dNTP concentration, reducing levels below those required by lentiviruses and other viruses to replicate. To counter this threat, some primate lentiviruses encode accessory proteins that bind SAMHD1 and induce its degradation; in turn, positive diversifying selection has been observed in regions bound by these lentiviral proteins, suggesting that primate SAMHD1 has coevolved to evade these countermeasures. Moreover, deleterious polymorphisms in human SAMHD1 are associated with autoimmune disease linked to uncontrolled DNA synthesis of endogenous retroelements. Little is known about how evolutionary pressures affect these different SAMHD1 functions. Here, we examine the deeper history of these interactions by testing whether evolutionary signatures in SAMHD1 extend to other mammalian groups and exploring the molecular basis of this coevolution. Using codon-based likelihood models, we find positive selection in SAMHD1 within each mammal lineage for which sequence data are available. We observe positive selection at sites clustered around T592, a residue that is phosphorylated to regulate SAMHD1 activity. We verify experimentally that mutations within this cluster affect catalytic rate and lentiviral restriction, suggesting that virus-host coevolution has required adaptations of enzymatic function. Thus, persistent positive selection may have involved the adaptation of SAMHD1 regulation to balance antiviral, metabolic, and innate immunity functions.
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Affiliation(s)
- Christopher Monit
- Division of Infection and Immunity, University College London, WC1E 6BT London, United Kingdom
| | - Elizabeth R Morris
- Macromolecular Structure Laboratory, The Francis Crick Institute, NW1 1AT London, United Kingdom
| | - Christopher Ruis
- Division of Infection and Immunity, University College London, WC1E 6BT London, United Kingdom
| | - Bart Szafran
- Retrovirus-Host Interactions Laboratory, The Francis Crick Institute, NW1 1AT London, United Kingdom
| | - Grant Thiltgen
- Division of Infection and Immunity, University College London, WC1E 6BT London, United Kingdom
| | - Ming-Han Chloe Tsai
- Retroviral Replication Laboratory, The Francis Crick Institute, NW1 1AT London, United Kingdom
| | - N Avrion Mitchison
- Division of Infection and Immunity, University College London, WC1E 6BT London, United Kingdom
| | - Kate N Bishop
- Retroviral Replication Laboratory, The Francis Crick Institute, NW1 1AT London, United Kingdom
| | - Jonathan P Stoye
- Retrovirus-Host Interactions Laboratory, The Francis Crick Institute, NW1 1AT London, United Kingdom
| | - Ian A Taylor
- Macromolecular Structure Laboratory, The Francis Crick Institute, NW1 1AT London, United Kingdom
| | - Ariberto Fassati
- Division of Infection and Immunity, University College London, WC1E 6BT London, United Kingdom;
| | - Richard A Goldstein
- Division of Infection and Immunity, University College London, WC1E 6BT London, United Kingdom;
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7
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Colomer-Lluch M, Castro-Gonzalez S, Serra-Moreno R. Ubiquitination and SUMOylation in HIV Infection: Friends and Foes. Curr Issues Mol Biol 2019; 35:159-194. [PMID: 31422939 DOI: 10.21775/cimb.035.159] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
As intracellular parasites, viruses hijack the cellular machinery to facilitate their replication and spread. This includes favouring the expression of their viral genes over host genes, appropriation of cellular molecules, and manipulation of signalling pathways, including the post-translational machinery. HIV, the causative agent of AIDS, is notorious for using post-translational modifications to generate infectious particles. Here, we discuss the mechanisms by which HIV usurps the ubiquitin and SUMO pathways to modify both viral and host factors to achieve a productive infection, and also how the host innate sensing system uses these post-translational modifications to hinder HIV replication.
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Affiliation(s)
- Marta Colomer-Lluch
- IrsiCaixa AIDS Research Institute, Hospital Germans Trias i Pujol, Badalona, Spain
| | - Sergio Castro-Gonzalez
- Department of Biological Sciences, College of Arts and Sciences, Texas Tech University, Lubbock, TX, USA
| | - Ruth Serra-Moreno
- Department of Biological Sciences, College of Arts and Sciences, Texas Tech University, Lubbock, TX, USA
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8
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Coggins SA, Holler JM, Kimata JT, Kim DH, Schinazi RF, Kim B. Efficient pre-catalytic conformational change of reverse transcriptases from SAMHD1 non-counteracting primate lentiviruses during dNTP incorporation. Virology 2019; 537:36-44. [PMID: 31442614 DOI: 10.1016/j.virol.2019.08.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 08/10/2019] [Accepted: 08/12/2019] [Indexed: 10/26/2022]
Abstract
Unlike HIV-1, HIV-2 and some SIV strains replicate at high dNTP concentrations even in macrophages due to their accessory proteins, Vpx or Vpr, that target SAMHD1 dNTPase for proteasomal degradation. We previously reported that HIV-1 reverse transcriptase (RT) efficiently synthesizes DNA even at low dNTP concentrations because HIV-1 RT displays faster pre-steady state kpol values than SAMHD1 counteracting lentiviral RTs. Here, since the kpol step consists of two sequential sub-steps post dNTP binding, conformational change and chemistry, we investigated which of the two sub-steps RTs from SAMHD1 non-counteracting viruses accelerate in order to complete reverse transcription in the limited dNTP pools found in macrophages. Our study demonstrates that RTs of SAMHD1 non-counteracting lentiviruses have a faster conformational change rate during dNTP incorporation, supporting that these lentiviruses may have evolved to harbor RTs that can efficiently execute the conformational change step in order to circumvent SAMHD1 restriction and dNTP depletion in macrophages.
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Affiliation(s)
- Si'Ana A Coggins
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, 30322, USA
| | - Jessica M Holler
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, 30322, USA
| | - Jason T Kimata
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, 77030, Texas, USA
| | - Dong-Hyun Kim
- College of Pharmacy, Kyung Hee University, Seoul, 04427, South Korea
| | - Raymond F Schinazi
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, 30322, USA
| | - Baek Kim
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, 30322, USA; College of Pharmacy, Kyung Hee University, Seoul, 04427, South Korea; Children's Healthcare of Atlanta, Atlanta, 30322, USA.
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9
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Mahboubi B, Gavegnano C, Kim DH, Schinazi RF, Kim B. Host SAMHD1 protein restricts endogenous reverse transcription of HIV-1 in nondividing macrophages. Retrovirology 2018; 15:69. [PMID: 30316304 PMCID: PMC6186296 DOI: 10.1186/s12977-018-0452-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 10/06/2018] [Indexed: 12/13/2022] Open
Abstract
Background SAM domain and HD domain containing protein 1 (SAMHD1) is a host anti-HIV-1 restriction factor known to suppress viral reverse transcription in nondividing myeloid cells by its dNTP triphosphorylase activity that depletes cellular dNTPs. However, HIV-2 and some SIV strains rapidly replicate in macrophages due to their accessory protein, viral protein X (Vpx), which proteosomally degrades SAMHD1 and elevates dNTP levels. Endogenous reverse transcription (ERT) of retroviruses is the extra-cellular reverse transcription step that partially synthesizes proviral DNAs within cell-free viral particles before the viruses infect new cells. ERT activity utilizes dNTPs co-packaged during budding from the virus-producing cells, and high ERT activity is known to enhance HIV-1 infectivity in nondividing cells. Here, since Vpx elevates cellular dNTP levels in macrophages, we hypothesize that HIV-2 should contain higher ERT activity than HIV-1 in macrophages, and that the Vpx-mediated dNTP elevation should enhance both ERT activity and infectivity of HIV-1 particles produced in macrophages. Results Here, we demonstrate that HIV-2 produced from human primary monocyte derived macrophages displays higher ERT activity than HIV-1 produced from macrophages. Also, HIV-1 particles produced from macrophages treated with virus like particles (VLPs) containing Vpx, Vpx (+), displayed large increases of ERT activity with the enhanced copy numbers of early, middle and late reverse transcription products within the viral particles, compared to the viruses produced from macrophages treated with Vpx (−) VLPs. Furthermore, upon the infection with an equal p24 amount to fresh macrophages, the viruses produced from the Vpx (+) VLP treated macrophages demonstrated higher infectivity than the viruses from the Vpx (−) VLP treated macrophages. Conclusions This finding identifies the viral ERT step as an additional step of HIV-1 replication cycle that SAMHD1 restricts in nondividing myeloid target cells. Electronic supplementary material The online version of this article (10.1186/s12977-018-0452-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Bijan Mahboubi
- Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, 30322, USA
| | - Christina Gavegnano
- Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, 30322, USA
| | - Dong-Hyun Kim
- School of Pharmacy, Kyung-Hee University, Seoul, South Korea
| | - Raymond F Schinazi
- Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, 30322, USA
| | - Baek Kim
- Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, 30322, USA. .,School of Pharmacy, Kyung-Hee University, Seoul, South Korea. .,Children's Healthcare of Atlanta, Atlanta, GA, USA.
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10
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Mereby SA, Maehigashi T, Holler JM, Kim DH, Schinazi RF, Kim B. Interplay of ancestral non-primate lentiviruses with the virus-restricting SAMHD1 proteins of their hosts. J Biol Chem 2018; 293:16402-16412. [PMID: 30181218 PMCID: PMC6200947 DOI: 10.1074/jbc.ra118.004567] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 08/29/2018] [Indexed: 11/26/2022] Open
Abstract
Lentiviruses infect both dividing CD4+ T cells and nondividing myeloid cells, and the infected myeloid cells serve as long-living viral reservoirs. Host sterile alpha motif– and histidine-aspartate domain–containing protein 1 (SAMHD1) kinetically restricts reverse transcription of primate lentiviruses, including human immunodeficiency virus, type 1 (HIV-1) and simian immunodeficiency virus (SIV), in nondividing myeloid cells. SAMHD1 enforces this restriction through its dNTP triphosphohydrolase (dNTPase) activity that depletes cellular dNTPs. Some primate lentiviruses, such as HIV-2, SIVsm, and SIVagm, counteract SAMHD1 restriction by using their viral accessory proteins (Vpx or Vpr) that induce the proteosomal degradation of SAMHD1 and increase dNTP levels. SAMHD1 is conserved among non-primate mammals such as cats, cows, and horses that also carry their own lentiviruses (feline and bovine immunodeficiency viruses and equine infectious anemia viruses, respectively). However, whether these viruses also target SAMHD1 is unknown. Here, we tested whether these ancestral non-primate lentiviruses also can counteract their host SAMHD1 proteins by promoting their proteosomal degradation. Using biochemical and various cell-based assays, we observed that SAMHD1 proteins from the non-primate host species display dGTP-dependent dNTPase activity, but that the non-primate lentiviruses fail to proteosomally degrade the SAMHD1 proteins of their hosts. Our findings suggest that accessory protein–mediated proteosomal degradation of SAMHD1 did not exist among the ancestral non-primate lentiviruses and was uniquely gained by some primate lentiviruses after their transmission to primate species.
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Affiliation(s)
- Sarah A Mereby
- From the Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia 30322
| | - Tatsuya Maehigashi
- From the Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia 30322
| | - Jessica M Holler
- From the Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia 30322
| | - Dong-Hyun Kim
- Department of Pharmacy, Kyung-Hee University, Seoul 130-701, South Korea, and
| | - Raymond F Schinazi
- From the Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia 30322
| | - Baek Kim
- From the Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia 30322, .,Department of Pharmacy, Kyung-Hee University, Seoul 130-701, South Korea, and.,Center for Drug Discovery, Children's Healthcare of Atlanta, Atlanta, Georgia 30322
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11
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Recurrent Loss of APOBEC3H Activity during Primate Evolution. J Virol 2018; 92:JVI.00971-18. [PMID: 29925657 DOI: 10.1128/jvi.00971-18] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 06/08/2018] [Indexed: 01/01/2023] Open
Abstract
Genes in the APOBEC3 family encode cytidine deaminases that provide a barrier against viral infection and retrotransposition. Of all the APOBEC3 genes in humans, APOBEC3H (A3H) is the most polymorphic: some genes encode stable and active A3H proteins, while others are unstable and poorly antiviral. Such variation in human A3H affects interactions with the lentiviral antagonist Vif, which counteracts A3H via proteasomal degradation. In order to broaden our understanding of A3H-Vif interactions, as well as its evolution in Old World monkeys, we characterized A3H variation within four African green monkey (AGM) subspecies. We found that A3H is highly polymorphic in AGMs and has lost antiviral activity in multiple Old World monkeys. This loss of function was partially related to protein expression levels but was also influenced by amino acid mutations in the N terminus. Moreover, we demonstrate that the evolution of A3H in the primate lineages leading to AGMs was not driven by Vif. Our work suggests that the activity of A3H is evolutionarily dynamic and may have a negative effect on host fitness, resulting in its recurrent loss in primates.IMPORTANCE Adaptation of viruses to their hosts is critical for viral transmission between different species. Previous studies had identified changes in a protein from the APOBEC3 family that influenced the species specificity of simian immunodeficiency viruses (SIVs) in African green monkeys. We studied the evolution of a related protein in the same system, APOBEC3H, which has experienced a loss of function in humans. This evolutionary approach revealed that recurrent loss of APOBEC3H activity has taken place during primate evolution, suggesting that APOBEC3H places a fitness cost on hosts. The variability of APOBEC3H activity between different primates highlights the differential selective pressures on the APOBEC3 gene family.
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12
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Sauter D, Kirchhoff F. Multilayered and versatile inhibition of cellular antiviral factors by HIV and SIV accessory proteins. Cytokine Growth Factor Rev 2018. [PMID: 29526437 DOI: 10.1016/j.cytogfr.2018.02.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
HIV-1, the main causative agent of AIDS, and related primate lentiviruses show a striking ability to efficiently replicate throughout the lifetime of an infected host. In addition to their high variability, the acquisition of several accessory genes has enabled these viruses to efficiently evade or counteract seemingly strong antiviral immune responses. The respective viral proteins, i.e. Vif, Vpr, Vpu, Vpx and Nef, show a stunning functional diversity, acting by various mechanisms and targeting a large variety of cellular factors involved in innate and adaptive immunity. A focus of the present review is the accumulating evidence that Vpr, Vpu and Nef not only directly target cellular antiviral factors at the protein level, but also suppress their expression by modulating the activity of immune-regulatory transcription factors such as NF-κB. Furthermore, we will discuss the ability of accessory proteins to act as versatile adaptors, removing antiviral proteins from their sites of action and/or targeting them for proteasomal or endolysosomal degradation. Here, the main emphasis will be on emerging examples for functional interactions, synergisms and switches between accessory primate lentiviral proteins. A better understanding of this complex interplay between cellular immune defense mechanisms and viral countermeasures might facilitate the development of effective vaccines, help to prevent harmful chronic inflammation, and provide insights into the establishment and maintenance of latent viral reservoirs.
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Affiliation(s)
- Daniel Sauter
- Institute of Molecular Virology, Ulm University Medical Center, Meyerhofstr. 1, 89081 Ulm, Germany.
| | - Frank Kirchhoff
- Institute of Molecular Virology, Ulm University Medical Center, Meyerhofstr. 1, 89081 Ulm, Germany.
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13
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Li W, Gorantla S, Gendelman HE, Poluektova LY. Systemic HIV-1 infection produces a unique glial footprint in humanized mouse brains. Dis Model Mech 2017; 10:1489-1502. [PMID: 29084769 PMCID: PMC5769612 DOI: 10.1242/dmm.031773] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 10/17/2017] [Indexed: 01/22/2023] Open
Abstract
Studies of innate glial cell responses for progressive human immunodeficiency virus type one (HIV-1) infection are limited by a dearth of human disease-relevant small-animal models. To overcome this obstacle, newborn NOD/SCID/IL2Rγc−/− (NSG) mice were reconstituted with a humanized brain and immune system. NSG animals of both sexes were transplanted with human neuroglial progenitor cells (NPCs) and hematopoietic stem cells. Intraventricular injection of NPCs symmetrically repopulated the mouse brain parenchyma with human astrocytes and oligodendrocytes. Human glia were in periventricular areas, white matter tracts, the olfactory bulb and the brain stem. HIV-1 infection led to meningeal and perivascular human leukocyte infiltration into the brain. Species-specific viral-neuroimmune interactions were identified by deep RNA sequencing. In the corpus callosum and hippocampus of infected animals, overlapping human-specific transcriptional alterations for interferon type 1 and 2 signaling pathways (STAT1, STAT2, IRF9, ISG15, IFI6) and a range of host antiviral responses (MX1, OAS1, RSAD2, BST2, SAMHD1) were observed. Glial cytoskeleton reorganization, oligodendrocyte differentiation and myelin ensheathment (MBP, MOBP, PLP1, MAG, ZNF488) were downregulated. The data sets were confirmed by real-time PCR. These viral defense-signaling patterns paralleled neuroimmune communication networks seen in HIV-1-infected human brains. In this manner, this new mouse model of neuroAIDS can facilitate diagnostic, therapeutic and viral eradication strategies for an infected nervous system. Summary: In mice with a humanized brain and immune system, systemic infection led to human-specific transcriptional induction of glial interferon antiviral innate immune pathways and alteration of neuronal progenitor differentiation and myelination.
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Affiliation(s)
- Weizhe Li
- Department of Pharmacology and Experimental Neuroscience, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska 68198-5880, USA
| | - Santhi Gorantla
- Department of Pharmacology and Experimental Neuroscience, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska 68198-5880, USA
| | - Howard E Gendelman
- Department of Pharmacology and Experimental Neuroscience, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska 68198-5880, USA
| | - Larisa Y Poluektova
- Department of Pharmacology and Experimental Neuroscience, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska 68198-5880, USA
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14
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The KT Jeang Retrovirology prize 2017: Michael Emerman. Retrovirology 2017. [PMID: 28637466 PMCID: PMC5480113 DOI: 10.1186/s12977-017-0362-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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15
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Compton AA, Roy N, Porrot F, Billet A, Casartelli N, Yount JS, Liang C, Schwartz O. Natural mutations in IFITM3 modulate post-translational regulation and toggle antiviral specificity. EMBO Rep 2016; 17:1657-1671. [PMID: 27601221 PMCID: PMC5090704 DOI: 10.15252/embr.201642771] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 08/03/2016] [Indexed: 01/14/2023] Open
Abstract
The interferon‐induced transmembrane (IFITM) proteins protect host cells from diverse virus infections. IFITM proteins also incorporate into HIV‐1 virions and inhibit virus fusion and cell‐to‐cell spread, with IFITM3 showing the greatest potency. Here, we report that amino‐terminal mutants of IFITM3 preventing ubiquitination and endocytosis are more abundantly incorporated into virions and exhibit enhanced inhibition of HIV‐1 fusion. An analysis of primate genomes revealed that IFITM3 is the most ancient antiviral family member of the IFITM locus and has undergone a repeated duplication in independent host lineages. Some IFITM3 genes in nonhuman primates, including those that arose following gene duplication, carry amino‐terminal mutations that modify protein localization and function. This suggests that “runaway” IFITM3 variants could be selected for altered antiviral activity. Furthermore, we show that adaptations in IFITM3 result in a trade‐off in antiviral specificity, as variants exhibiting enhanced activity against HIV‐1 poorly restrict influenza A virus. Overall, we provide the first experimental evidence that diversification of IFITM3 genes may boost the antiviral coverage of host cells and provide selective functional advantages.
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Affiliation(s)
| | - Nicolas Roy
- Virus & Immunity Unit, Institut Pasteur, Paris, France
| | | | - Anne Billet
- Virus & Immunity Unit, Institut Pasteur, Paris, France
| | | | - Jacob S Yount
- Department of Microbial Infection & Immunity, The Ohio State University, Columbus, OH, USA
| | - Chen Liang
- Lady Davis Institute, McGill University, Montreal, QC, Canada
| | - Olivier Schwartz
- Virus & Immunity Unit, Institut Pasteur, Paris, France .,CNRS-URA 3015, Paris, France.,Vaccine Research Institute, Creteil, France
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16
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Characterization of the interactions between SIVrcm Vpx and red-capped mangabey SAMHD1. Biochem J 2015; 468:303-13. [DOI: 10.1042/bj20141331] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We have characterized the interactions between SIVrcm Vpx and the N-terminal domain of rcmSAMHD1. The results advance our understanding of the ‘arms race’ between Vpx and SAMHD1.
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17
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Schwefel D, Boucherit VC, Christodoulou E, Walker PA, Stoye JP, Bishop KN, Taylor IA. Molecular determinants for recognition of divergent SAMHD1 proteins by the lentiviral accessory protein Vpx. Cell Host Microbe 2015; 17:489-99. [PMID: 25856754 PMCID: PMC4400269 DOI: 10.1016/j.chom.2015.03.004] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 01/31/2015] [Accepted: 02/27/2015] [Indexed: 11/22/2022]
Abstract
The SAMHD1 triphosphohydrolase inhibits HIV-1 infection of myeloid and resting T cells by depleting dNTPs. To overcome SAMHD1, HIV-2 and some SIVs encode either of two lineages of the accessory protein Vpx that bind the SAMHD1 N or C terminus and redirect the host cullin-4 ubiquitin ligase to target SAMHD1 for proteasomal degradation. We present the ternary complex of Vpx from SIV that infects mandrills (SIVmnd-2) with the cullin-4 substrate receptor, DCAF1, and N-terminal and SAM domains from mandrill SAMHD1. The structure reveals details of Vpx lineage-specific targeting of SAMHD1 N-terminal "degron" sequences. Comparison with Vpx from SIV that infects sooty mangabeys (SIVsmm) complexed with SAMHD1-DCAF1 identifies molecular determinants directing Vpx lineages to N- or C-terminal SAMHD1 sequences. Inspection of the Vpx-DCAF1 interface also reveals conservation of Vpx with the evolutionally related HIV-1/SIV accessory protein Vpr. These data suggest a unified model for how Vpx and Vpr exploit DCAF1 to promote viral replication.
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Affiliation(s)
- David Schwefel
- Division of Molecular Structure, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Virginie C Boucherit
- Division of Virology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Evangelos Christodoulou
- Division of Molecular Structure, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Philip A Walker
- Division of Molecular Structure, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Jonathan P Stoye
- Division of Virology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK; Faculty of Medicine, Imperial College London, London SW7 2AZ, UK
| | - Kate N Bishop
- Division of Virology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK.
| | - Ian A Taylor
- Division of Molecular Structure, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK.
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18
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Berger G, Lawrence M, Hué S, Neil SJD. G2/M cell cycle arrest correlates with primate lentiviral Vpr interaction with the SLX4 complex. J Virol 2015; 89:230-40. [PMID: 25320300 PMCID: PMC4301105 DOI: 10.1128/jvi.02307-14] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 10/06/2014] [Indexed: 01/15/2023] Open
Abstract
UNLABELLED The accessory gene vpr, common to all primate lentiviruses, induces potent G2/M arrest in cycling cells. A recent study showed that human immunodeficiency virus type 1 (HIV-1) viral protein R (Vpr) mediates this through activation of the SLX4/MUS81/EME1 exonuclease complex that forms part of the Fanconi anemia DNA repair pathway. To confirm these observations, we have examined the G2/M arrest phenotypes of a panel of simian immunodeficiency virus (SIV) Vpr proteins. We show that SIV Vpr proteins differ in their ability to promote cell cycle arrest in human cells. While this is dependent on the DCAF1/DDB1/CUL4 ubiquitin ligase complex, interaction with human DCAF1 does not predict G2/M arrest activity of SIV Vpr in human cells. In all cases, SIV Vpr-mediated cell cycle arrest in human cells correlated with interaction with human SLX4 (huSLX4) and could be abolished by small interfering RNA (siRNA) depletion of any member of the SLX4 complex. In contrast, all but one of the HIV/SIV Vpr proteins tested, including those that lacked activity in human cells, were competent for G2/M arrest in grivet cells. Correspondingly, here cell cycle arrest correlated with interaction with the grivet orthologues of the SLX4 complex, suggesting a level of host adaptation in these interactions. Phylogenetic analyses strongly suggest that G2/M arrest/SLX4 interactions are ancestral activities of primate lentiviral Vpr proteins and that the ability to dysregulate the Fanconi anemia DNA repair pathway is an essential function of Vpr in vivo. IMPORTANCE The Vpr protein of HIV-1 and related viruses is essential for the virus in vivo. The ability of Vpr to block the cell cycle at mitotic entry is well known, but the importance of this function for viral replication is unclear. Recent data have shown that HIV-1 Vpr targets the Fanconi anemia DNA repair pathway by interacting with and activating an endonuclease complex, SLX4/MUS81/EME1, that processes interstrand DNA cross-links. Here we show that the ability of a panel of SIV Vpr proteins to mediate cell cycle arrest correlates with species-specific interactions with the SLX4 complex in human and primate cells. The results of these studies suggest that the SLX4 complex is a conserved target of primate lentiviral Vpr proteins and that the ability to dysregulate members of the Fanconi anemia DNA repair pathway is essential for HIV/SIV replication in vivo.
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Affiliation(s)
- Gregory Berger
- Department of Infectious Diseases, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
| | - Madeleine Lawrence
- Department of Infectious Diseases, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
| | - Stephane Hué
- MRC Centre for Medical Molecular Virology, University College London, London, United Kingdom
| | - Stuart J D Neil
- Department of Infectious Diseases, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
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19
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White TE, Brandariz-Nuñez A, Valle-Casuso JC, Knowlton C, Kim B, Sawyer SL, Diaz-Griffero F. Effects of human SAMHD1 polymorphisms on HIV-1 susceptibility. Virology 2014; 460-461:34-44. [PMID: 25010268 DOI: 10.1016/j.virol.2014.04.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 01/11/2014] [Accepted: 04/17/2014] [Indexed: 11/29/2022]
Abstract
SAMHD1 is a human restriction factor that prevents efficient infection of macrophages, dendritic cells and resting CD4+ T cells by HIV-1. Here we explored the antiviral activity and biochemical properties of human SAMHD1 polymorphisms. Our studies focused on human SAMHD1 polymorphisms that were previously identified as evolving under positive selection for rapid amino acid replacement during primate speciation. The different human SAMHD1 polymorphisms were tested for their ability to block HIV-1, HIV-2 and equine infectious anemia virus (EIAV). All studied SAMHD1 variants block HIV-1, HIV-2 and EIAV infection when compared to wild type. We found that these variants did not lose their ability to oligomerize or to bind RNA. Furthermore, all tested variants were susceptible to degradation by Vpx, and localized to the nuclear compartment. We tested the ability of human SAMHD1 polymorphisms to decrease the dNTP cellular levels. In agreement, none of the different SAMHD1 variants lost their ability to reduce cellular levels of dNTPs. Finally, we found that none of the tested human SAMHD1 polymorphisms affected the ability of the protein to block LINE-1 retrotransposition.
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Affiliation(s)
- Tommy E White
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, 1301 Morris Park - Price Center 501, New York, NY 10461, USA
| | - Alberto Brandariz-Nuñez
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, 1301 Morris Park - Price Center 501, New York, NY 10461, USA
| | - Jose Carlos Valle-Casuso
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, 1301 Morris Park - Price Center 501, New York, NY 10461, USA
| | - Caitlin Knowlton
- Department of Microbiology & Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Baek Kim
- Department of Microbiology & Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Sara L Sawyer
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Felipe Diaz-Griffero
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, 1301 Morris Park - Price Center 501, New York, NY 10461, USA.
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20
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Schaller T, Bauby H, Hué S, Malim MH, Goujon C. New insights into an X-traordinary viral protein. Front Microbiol 2014; 5:126. [PMID: 24782834 PMCID: PMC3986551 DOI: 10.3389/fmicb.2014.00126] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 03/11/2014] [Indexed: 11/13/2022] Open
Abstract
Vpx is a protein encoded by members of the HIV-2/SIVsmm and SIVrcm/SIVmnd-2 lineages of primate lentiviruses, and is packaged into viral particles. Vpx plays a critical role during the early steps of the viral life cycle and has been shown to counteract SAMHD1, a restriction factor in myeloid and resting T cells. However, it is becoming evident that Vpx is a multifunctional protein in that SAMHD1 antagonism is likely not its sole role. This review summarizes the current knowledge on this X-traordinary protein.
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Affiliation(s)
- Torsten Schaller
- Department of Infectious Diseases, King's College London London, UK
| | - Hélène Bauby
- Department of Infectious Diseases, King's College London London, UK
| | - Stéphane Hué
- Department of Infection, Division of Infection and Immunity, Centre for Medical Molecular Virology, University College London London, UK
| | - Michael H Malim
- Department of Infectious Diseases, King's College London London, UK
| | - Caroline Goujon
- Department of Infectious Diseases, King's College London London, UK
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21
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Dendritic cell-lymphocyte cross talk downregulates host restriction factor SAMHD1 and stimulates HIV-1 replication in dendritic cells. J Virol 2014; 88:5109-21. [PMID: 24574390 DOI: 10.1128/jvi.03057-13] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
UNLABELLED Human immunodeficiency virus type 1 (HIV-1) replication in dendritic cells (DCs) is restricted by SAMHD1. This factor is counteracted by the viral protein Vpx; Vpx is found in HIV-2 and simian immunodeficiency virus (SIV) from sooty mangabeys (SIVsm) or from macaques (SIVmac) but is absent from HIV-1. We previously observed that HIV-1 replication in immature DCs is stimulated by cocultivation with primary T and B lymphocytes, suggesting that HIV-1 restriction in DCs may be overcome under coculture conditions. Here, we aimed to decipher the mechanism of SAMHD1-mediated restriction in DC-lymphocyte coculture. We found that coculture with lymphocytes downregulated SAMHD1 expression and was associated with increased HIV-1 replication in DCs. Moreover, in infected DC-T lymphocyte cocultures, DCs acquired maturation status and secreted type 1 interferon (alpha interferon [IFN-α]). The blockade of DC-lymphocyte cross talk by anti-ICAM-1 antibody markedly inhibited the stimulation of HIV-1 replication and prevented the downregulation of SAMHD1 expression in cocultured DCs. These results demonstrate that, in contrast to purified DCs, cross talk with lymphocytes downregulates SAMHD1 expression in DCs, triggering HIV-1 replication and an antiviral immune response. Therefore, HIV-1 replication and immune sensing by DCs should be investigated in more physiologically relevant models of DC/lymphocyte coculture. IMPORTANCE SAMHD1 restricts HIV-1 replication in dendritic cells (DCs). Here, we demonstrate that, in a coculture model of DCs and lymphocytes mimicking early mucosal HIV-1 infection, stimulation of HIV-1 replication in DCs is associated with downregulation of SAMHD1 expression and activation of innate immune sensing by DCs. We propose that DC-lymphocyte cross talk occurring in vivo modulates host restriction factor SAMHD1, promoting HIV-1 replication in cellular reservoirs and stimulating immune sensing.
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