scholarly journals Contribution of the Cytoplasmic Determinants of Vpu to the Expansion of Virus-Containing Compartments in HIV-1-Infected Macrophages

2019 ◽  
Vol 93 (11) ◽  
Author(s):  
Olivier Leymarie ◽  
Leslie Lepont ◽  
Margaux Versapuech ◽  
Delphine Judith ◽  
Sophie Abelanet ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Viral Particle ◽  
Transmembrane Domain ◽  
Immune Surveillance ◽  
Restriction Factor ◽  
Viral Particles ◽  
Protein Functions ◽  
Specific Accumulation ◽  
Model Cell ◽  
Hiv 1

ABSTRACTHIV-1 infection of macrophages leads to the sequestration of newly formed viruses in intracellular plasma membrane-connected structures termed virus-containing compartments (VCCs), where virions remain infectious and hidden from immune surveillance. The cellular restriction factor bone marrow stromal cell antigen 2 (BST2), which prevents HIV-1 dissemination by tethering budding viral particles at the plasma membrane, can be found in VCCs. The HIV-1 accessory protein Vpu counteracts the restriction factor BST2 by downregulating its expression and removing it from viral budding sites. Numerous studies described these Vpu countermeasures in CD4+T cells or model cell lines, but the interplay between Vpu and BST2 in VCC formation and HIV-1 production in macrophages is less explored. Here, we show that Vpu expression in HIV-1-infected macrophages enhances viral release. This effect is related to Vpu’s ability to circumvent BST2 antiviral activity. We show that in absence of Vpu, BST2 is enriched in VCCs and colocalizes with capsid p24, whereas Vpu expression significantly reduces the presence of BST2 in these compartments. Furthermore, our data reveal that BST2 is dispensable for the formation of VCCs and that Vpu expression impacts the volume of these compartments. This Vpu activity partly depends on BST2 expression and requires the integrity of the Vpu transmembrane domain, the dileucine-like motif E59XXXLV64and phosphoserines 52 and 56 of Vpu. Altogether, these results highlight that Vpu controls the volume of VCCs and promotes HIV-1 release from infected macrophages.IMPORTANCEHIV-1 infection of macrophages leads to the sequestration of newly formed viruses in virus-containing compartments (VCCs), where virions remain infectious and hidden from immune surveillance. The restriction factor BST2, which prevents HIV-1 dissemination by tethering budding viral particles, can be found in VCCs. The HIV-1 Vpu protein counteracts BST2. This study explores the interplay between Vpu and BST2 in the viral protein functions on HIV-1 release and viral particle sequestration in VCCs in macrophages. The results show that Vpu controls the volume of VCCs and favors viral particle release. These Vpu functions partly depend on Vpu’s ability to antagonize BST2. This study highlights that the transmembrane domain of Vpu and two motifs of the Vpu cytoplasmic domain are required for these functions. These motifs were notably involved in the control of the volume of VCCs by Vpu but were dispensable for the prevention of the specific accumulation of BST2 in these structures.

scholarly journals Identification of SERINC5-001 as the Predominant Spliced Isoform for HIV-1 Restriction

2017 ◽  
Vol 91 (10) ◽  
Author(s):  
Xianfeng Zhang ◽  
Tao Zhou ◽  
Jie Yang ◽  
Yumei Lin ◽  
Jing Shi ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Transmembrane Domain ◽  
The Other ◽  
Stable Expression ◽  
Membrane Localization ◽  
Plasma Membrane Localization ◽  
Immunodeficiency Virus ◽  
Alternatively Spliced ◽  
Anti Hiv ◽  
Hiv 1

ABSTRACT Among the five serine incorporator (SERINC) family members, SERINC5 (Ser5) was reported to strongly inhibit HIV-1 replication, which is counteracted by Nef. Ser5 produces 5 alternatively spliced isoforms: Ser5-001 has 10 putative transmembrane domains, whereas Ser5-004, -005, -008a, and -008b do not have the last one. Here, we confirmed the strong Ser5 anti-HIV-1 activity and investigated its isoforms' expression and antiviral activities. It was found that Ser5-001 transcripts were detected at least 10-fold more than the other isoforms by real-time quantitative PCR. When Ser5-001 and its two isoforms Ser5-005 and Ser5-008a were expressed from the same mammalian expression vector, only Ser5-001 was stably expressed, whereas the others were poorly expressed due to rapid degradation. In addition, unlike the other isoforms, which are located mainly in the cytoplasm, Ser5-001 is localized primarily to the plasma membrane. To map the critical determinant, Ser5 mutants bearing C-terminal deletions were created. It was found that the 10th transmembrane domain is required for Ser5 stable expression and plasma membrane localization. As expected, only Ser5-001 strongly inhibits HIV-1 infectivity, whereas the other Ser5 isoforms and mutants that do not have the 10th transmembrane domain show very poor activity. It was also observed that the Nef counteractive activity could be easily saturated by Ser5 overexpression. Thus, we conclude that Ser5-001 is the predominant antiviral isoform that restricts HIV-1, and the 10th transmembrane domain plays a critical role in this process by regulating its protein stability and plasma membrane targeting. IMPORTANCE Human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) express a small protein, Nef, to enhance viral pathogenesis in vivo. Nef has an important in vitro function, which is to make virus particles more infectious, but the mechanism has been unclear. Recently, Nef was reported to counteract a novel anti-HIV host protein, SERINC5 (Ser5). Ser5 has five alternatively spliced isoforms, Ser5-001, -004, -005, -008a, and -008b, and only Ser5-001 has an extra C-terminal transmembrane domain. We now show that the Ser5-001 transcripts are produced at least 10-fold more than the others, and only Ser5-001 produces stable proteins that are targeted to the plasma membrane. Importantly, only Ser5-001 shows strong anti-HIV-1 activity. We further demonstrate that the extra transmembrane domain is required for Ser5 stable expression and plasma membrane localization. These results suggest that plasma membrane localization is required for Ser5 antiviral activity, and Ser5-001 is the predominant isoform that contributes to the activity.

scholarly journals The host-cell restriction factor SERINC5 restricts HIV-1 infectivity without altering the lipid composition and organization of viral particles

2017 ◽  
Vol 292 (33) ◽  
pp. 13702-13713 ◽  
Author(s):  
Birthe Trautz ◽  
Hannah Wiedemann ◽  
Christian Lüchtenborg ◽  
Virginia Pierini ◽  
Jan Kranich ◽  
...  
Keyword(s):  
Host Cell ◽  
Lipid Composition ◽  
Restriction Factor ◽  
Viral Particles ◽  
Hiv 1

scholarly journals Plasma Membrane-Associated Restriction Factors and Their Counteraction by HIV-1 Accessory Proteins

Cells ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 1020 ◽  
Author(s):  
Ramirez ◽  
Sharma ◽  
Singh ◽  
Stoneham ◽  
Vollbrecht ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Trafficking ◽  
Immune Surveillance ◽  
Viral Envelope ◽  
Accessory Proteins ◽  
Host Defenses ◽  
Restriction Factors ◽  
Associated Proteins ◽  
Infected Cells ◽  
Hiv 1

The plasma membrane is a site of conflict between host defenses and many viruses. One aspect of this conflict is the host’s attempt to eliminate infected cells using innate and adaptive cell-mediated immune mechanisms that recognize features of the plasma membrane characteristic of viral infection. Another is the expression of plasma membrane-associated proteins, so-called restriction factors, which inhibit enveloped virions directly. HIV-1 encodes two countermeasures to these host defenses: The membrane-associated accessory proteins Vpu and Nef. In addition to inhibiting cell-mediated immune-surveillance, Vpu and Nef counteract membrane-associated restriction factors. These include BST-2, which traps newly formed virions at the plasma membrane unless counteracted by Vpu, and SERINC5, which decreases the infectivity of virions unless counteracted by Nef. Here we review key features of these two antiviral proteins, and we review Vpu and Nef, which deplete them from the plasma membrane by co-opting specific cellular proteins and pathways of membrane trafficking and protein-degradation. We also discuss other plasma membrane proteins modulated by HIV-1, particularly CD4, which, if not opposed in infected cells by Vpu and Nef, inhibits viral infectivity and increases the sensitivity of the viral envelope glycoprotein to host immunity.

scholarly journals Upregulation of BST-2 by Type I Interferons Reduces the Capacity of Vpu To Protect HIV-1-Infected Cells from NK Cell Responses

mBio ◽  
2019 ◽  
Vol 10 (3) ◽  
Author(s):  
Jérémie Prévost ◽  
Suzanne Pickering ◽  
Mitchell J. Mumby ◽  
Halima Medjahed ◽  
Gabrielle Gendron-Lepage ◽  
...  
Keyword(s):  
Transmembrane Domain ◽  
Nk Cell ◽  
Restriction Factor ◽  
Type I ◽  
Cell Responses ◽  
Viral Release ◽  
Type I Ifns ◽  
Infected Cells ◽  
Ifn Treatment ◽  
Hiv 1

ABSTRACTThe HIV-1 accessory protein Vpu enhances viral release by counteracting the restriction factor BST-2. Furthermore, Vpu promotes NK cell evasion by downmodulating cell surface NTB-A and PVR, known ligands of the NK cell receptors NTB-A and DNAM-1, respectively. While it has been established that Vpu’s transmembrane domain (TMD) is required for the interaction and intracellular sequestration of BST-2, NTB-A, and PVR, it remains unclear how Vpu manages to target these proteins simultaneously. In this study, we show that upon upregulation, BST-2 is preferentially downregulated by Vpu over its other TMD substrates. We found that type I interferon (IFN)-mediated BST-2 upregulation greatly impairs the ability of Vpu to downregulate NTB-A and PVR. Our results suggest that occupation of Vpu by BST-2 affects its ability to downregulate other TMD substrates. Accordingly, knockdown of BST-2 increases Vpu’s potency to downmodulate NTB-A and PVR in the presence of type I IFN treatment. Moreover, we show that expression of human BST-2, but not that of the macaque orthologue, decreases Vpu’s capacity to downregulate NTB-A. Importantly, we show that type I IFNs efficiently sensitize HIV-1-infected cells to NTB-A- and DNAM-1-mediated direct and antibody-dependent NK cell responses. Altogether, our results reveal that type I IFNs decrease Vpu’s polyfunctionality, thus reducing its capacity to protect HIV-1-infected cells from NK cell responses.IMPORTANCEThe restriction factor BST-2 and the NK cell ligands NTB-A and PVR are among a growing list of membrane proteins found to be downregulated by HIV-1 Vpu. BST-2 antagonism enhances viral release, while NTB-A and PVR downmodulation contributes to NK cell evasion. However, it remains unclear how Vpu can target multiple cellular factors simultaneously. Here we provide evidence that under physiological conditions, BST-2 is preferentially targeted by Vpu over NTB-A and PVR. Specifically, we show that type I IFNs decrease Vpu’s polyfunctionality by upregulating BST-2, thus reducing its capacity to protect HIV-1-infected cells from NK cell responses. This indicates that there is a hierarchy of Vpu substrates upon IFN treatment, revealing that for the virus, targeting BST-2 as part of its resistance to IFN takes precedence over evading NK cell responses. This reveals a potential weakness in HIV-1’s immunoevasion mechanisms that may be exploited therapeutically to harness NK cell responses against HIV-1.

scholarly journals HIV-1 Vpu Antagonizes CD317/Tetherin by Adaptor Protein-1-Mediated Exclusion from Virus Assembly Sites

2016 ◽  
Vol 90 (15) ◽  
pp. 6709-6723 ◽  
Author(s):  
François M. Pujol ◽  
Vibor Laketa ◽  
Florian Schmidt ◽  
Markus Mukenhirn ◽  
Barbara Müller ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Virus Assembly ◽  
Adaptor Protein ◽  
Restriction Factor ◽  
Dependent Manner ◽  
Anterograde Transport ◽  
Particle Release ◽  
Hiv 1 ◽  
Tetherin Antagonism

ABSTRACTThe host cell restriction factor CD317/tetherin traps virions at the surface of producer cells to prevent their release. The HIV-1 accessory protein Vpu antagonizes this restriction. Vpu reduces the cell surface density of the restriction factor and targets it for degradation; however, these activities are dispensable for enhancing particle release. Instead, Vpu has been suggested to antagonize CD317/tetherin by preventing recycling of internalized CD317/tetherin to the cell surface, blocking anterograde transport of newly synthesized CD317/tetherin, and/or displacing the restriction factor from virus assembly sites at the plasma membrane. At the molecular level, antagonism relies on the physical interaction of Vpu with CD317/tetherin. Recent findings suggested that phosphorylation of a diserine motif enables Vpu to bind to adaptor protein 1 (AP-1) trafficking complexes via two independent interaction motifs and to couple CD317/tetherin to the endocytic machinery. Here, we used a panel of Vpu proteins with specific mutations in individual interaction motifs to define which interactions are required for antagonism of CD317/tetherin. Impairing recycling or anterograde transport of CD317/tetherin to the plasma membrane was insufficient for antagonism. In contrast, excluding CD317/tetherin from HIV-1 assembly sites depended on Vpu motifs for interaction with AP-1 and CD317/tetherin and correlated with antagonism of the particle release restriction. Consistently, interference with AP-1 function or its expression blocked these Vpu activities. Our results define displacement from HIV-1 assembly sites as active principle of CD317/tetherin antagonism by Vpu and support a role of tripartite complexes between Vpu, AP-1, and CD317/tetherin in this process.IMPORTANCECD317/tetherin poses an intrinsic barrier to human immunodeficiency virus type 1 (HIV-1) replication in human cells by trapping virus particles at the surface of producer cells and thereby preventing their release. The viral protein Vpu antagonizes this restriction, and molecular interactions with the restriction factor and adaptor protein complex 1 (AP-1) were suggested to mediate this activity. Vpu modulates intracellular trafficking of CD317/tetherin and excludes the restriction factor from HIV-1 assembly sites at the plasma membrane, but the relative contribution of these effects to antagonism remain elusive. Using a panel of Vpu mutants, as well as interference with AP-1 function and expression, we show here that Vpu antagonizes CD317/tetherin by blocking its recruitment to viral assembly sites in an AP-1-dependent manner. These results refine our understanding of the molecular mechanisms of CD317/tetherin antagonism and suggest complexes of Vpu with the restriction factor and AP-1 as targets for potential therapeutic intervention.

scholarly journals Correction: The host-cell restriction factor SERINC5 restricts HIV-1 infectivity without altering the lipid composition and organization of viral particles.

2019 ◽  
Vol 294 (49) ◽  
pp. 18951-18951
Author(s):  
Birthe Trautz ◽  
Hanna Wiedemann ◽  
Christian Lüchtenborg ◽  
Virginia Pierini ◽  
Jan Kranich ◽  
...  
Keyword(s):  
Host Cell ◽  
Lipid Composition ◽  
Restriction Factor ◽  
Viral Particles ◽  
Hiv 1

scholarly journals HIV-1 specifically traps CD9 and CD81 tetraspanins within viral buds and induces their membrane depletion

2018 ◽  
Author(s):  
Selma Dahmane ◽  
Christine Doucet ◽  
Antoine Le Gall ◽  
Célia Chamontin ◽  
Patrice Dosset ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Plasma Membrane ◽  
Super Resolution ◽  
Induced Membrane ◽  
Force Microscopy ◽  
Atomic Force ◽  
Membrane Topography ◽  
Viral Particles ◽  
Super Resolution Microscopy ◽  
Hiv 1

SUMMARYHIV-1 assembly specifically alters both partitioning and dynamics of the tetraspanins CD9 and CD81 forming enriched areas where the virus buds. Importantly the presence of these proteins at exit sites and in viral particles inhibits virus-induced membrane fusion. To get molecular insights into tetraspanins partitioning in this viral context, we correlated nanoscale CD9 mapping obtained by super resolution microscopy to membrane topography probed by Atomic Force Microscopy (AFM). We demonstrated that CD9 is specifically trapped within the nascent viral particles, especially at buds tips, and that Gag mediate CD9 and CD81 depletion from cellular surfaces, even in the absence of Vpu and Nef, resulting from tetraspanins escaping from the plasma membrane during HIV-1 release. In addition, we showed that CD9 is organized as small membrane assemblies of few tens of nanometers that can coalesce upon Gag expression. Our results support a functional redundancy among tetraspanins during HIV release.

scholarly journals G2-S16 Polyanionic Carbosilane Dendrimer Can Reduce HIV-1 Reservoir Formation by Inhibiting Macrophage Cell to Cell Transmission

2021 ◽  
Vol 22 (16) ◽  
pp. 8366
Author(s):  
Ignacio Relaño-Rodríguez ◽  
María de la Sierra Espinar-Buitrago ◽  
Vanessa Martín-Cañadilla ◽  
Rafael Gómez-Ramírez ◽  
María Ángeles Muñoz-Fernández
Keyword(s):  
T Cells ◽  
Developed Countries ◽  
Main Role ◽  
Viral Particles ◽  
Carbosilane Dendrimer ◽  
Science Community ◽  
New Compounds ◽  
Hiv 1

Human immunodeficiency virus (HIV-1) is still a major problem, not only in developing countries but is also re-emerging in several developed countries, thus the development of new compounds able to inhibit the virus, either for prophylaxis or treatment, is still needed. Nanotechnology has provided the science community with several new tools for biomedical applications. G2-S16 is a polyanionic carbosilane dendrimer capable of inhibiting HIV-1 in vitro and in vivo by interacting directly with viral particles. One of the main barriers for HIV-1 eradication is the reservoirs created in primoinfection. These reservoirs, mainly in T cells, are untargetable by actual drugs or immune system. Thus, one approach is inhibiting HIV-1 from reaching these reservoir cells. In this context, macrophages play a main role as they can deliver viral particles to T cells establishing reservoirs. We showed that G2-S16 dendrimer is capable of inhibiting the infection from infected macrophages to healthy T CD4/CD8 lymphocytes by eliminating HIV-1 infectivity inside macrophages, so they are not able to carry infectious particles to other body locations, thus preventing the reservoirs from forming.

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