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Fert A, Richard J, Marchand LR, Planas D, Routy JP, Chomont N, Finzi A, Ancuta P. Metformin Enhances Antibody-Mediated Recognition of HIV-Infected CD4 + T-Cells by Decreasing Viral Release. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.15.580166. [PMID: 38464135 PMCID: PMC10925111 DOI: 10.1101/2024.02.15.580166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
The mechanistic target of rapamycin (mTOR) positively regulates multiple steps of the HIV-1 replication cycle. We previously reported that a 12-weeks supplementation of antiretroviral therapy (ART) with metformin, an indirect mTOR inhibitor used in type-2 diabetes treatment, reduced mTOR activation and HIV transcription in colon-infiltrating CD4+ T-cells, together with systemic inflammation in nondiabetic people with HIV-1 (PWH). Herein, we investigated the antiviral mechanisms of metformin. In a viral outgrowth assay performed with CD4+ T-cells from ART-treated PWH, and upon infection in vitro with replication-competent and VSV-G-pseudotyped HIV-1, metformin decreased virion release, but increased the frequency of productively infected CD4lowHIV-p24+ T-cells. These observations coincided with increased BST2/Tetherin (HIV release inhibitor) and Bcl-2 (pro-survival factor) expression, and improved recognition of productively infected T-cells by HIV-1 Envelope antibodies. Thus, metformin exerts pleiotropic effects on post-transcription/translation steps of the HIV-1 replication cycle and may be used to accelerate viral reservoir decay in ART-treated PWH.
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Affiliation(s)
- Augustine Fert
- Centre de recherche du Centre hospitalier de l’Université de Montréal, Montréal, QC, H2X 0A9, Canada
- Département de microbiologie, infectiologie et immunologie, Faculté de médecine, Université de Montréal, Montréal, QC, H3C 3J7, Canada
| | - Jonathan Richard
- Centre de recherche du Centre hospitalier de l’Université de Montréal, Montréal, QC, H2X 0A9, Canada
- Département de microbiologie, infectiologie et immunologie, Faculté de médecine, Université de Montréal, Montréal, QC, H3C 3J7, Canada
| | - Laurence Raymond Marchand
- Centre de recherche du Centre hospitalier de l’Université de Montréal, Montréal, QC, H2X 0A9, Canada
| | - Delphine Planas
- Centre de recherche du Centre hospitalier de l’Université de Montréal, Montréal, QC, H2X 0A9, Canada
- Département de microbiologie, infectiologie et immunologie, Faculté de médecine, Université de Montréal, Montréal, QC, H3C 3J7, Canada
| | - Jean-Pierre Routy
- Infectious Diseases and Immunity in Global Health Program, Research Institute, McGill University Health Centre, Montréal, QC, Canada
- Chronic Viral Illness Service, McGill University Health Centre, Montréal, QC, Canada
- Division of Hematology, McGill University Health Centre, Montreal, QC, Canada
| | - Nicolas Chomont
- Centre de recherche du Centre hospitalier de l’Université de Montréal, Montréal, QC, H2X 0A9, Canada
- Département de microbiologie, infectiologie et immunologie, Faculté de médecine, Université de Montréal, Montréal, QC, H3C 3J7, Canada
| | - Andrés Finzi
- Centre de recherche du Centre hospitalier de l’Université de Montréal, Montréal, QC, H2X 0A9, Canada
- Département de microbiologie, infectiologie et immunologie, Faculté de médecine, Université de Montréal, Montréal, QC, H3C 3J7, Canada
| | - Petronela Ancuta
- Centre de recherche du Centre hospitalier de l’Université de Montréal, Montréal, QC, H2X 0A9, Canada
- Département de microbiologie, infectiologie et immunologie, Faculté de médecine, Université de Montréal, Montréal, QC, H3C 3J7, Canada
- Lead Contact
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2
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Pickering S, Sumner J, Kerridge C, Perera M, Neil S. Differential dysregulation of β-TrCP1 and -2 by HIV-1 Vpu leads to inhibition of canonical and non-canonical NF-κB pathways in infected cells. mBio 2023; 14:e0329322. [PMID: 37341489 PMCID: PMC10470808 DOI: 10.1128/mbio.03293-22] [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: 11/25/2022] [Accepted: 04/03/2023] [Indexed: 06/22/2023] Open
Abstract
The HIV-1 Vpu protein is expressed late in the virus lifecycle to promote infectious virus production and avoid innate and adaptive immunity. This includes the inhibition of the NF-κB pathway which, when activated, leads to the induction of inflammatory responses and the promotion of antiviral immunity. Here we demonstrate that Vpu can inhibit both canonical and non-canonical NF-κB pathways, through the direct inhibition of the F-box protein β-TrCP, the substrate recognition portion of the Skp1-Cul1-F-box (SCF)β-TrCP ubiquitin ligase complex. There are two paralogues of β-TrCP (β-TrCP1/BTRC and β-TrCP2/FBXW11), encoded on different chromosomes, which appear to be functionally redundant. Vpu, however, is one of the few β-TrCP substrates to differentiate between the two paralogues. We have found that patient-derived alleles of Vpu, unlike those from lab-adapted viruses, trigger the degradation of β-TrCP1 while co-opting its paralogue β-TrCP2 for the degradation of cellular targets of Vpu, such as CD4. The potency of this dual inhibition correlates with stabilization of the classical IκBα and the phosphorylated precursors of the mature DNA-binding subunits of canonical and non-canonical NF-κB pathways, p105/NFκB1 and p100/NFκB2, in HIV-1 infected CD4+ T cells. Both precursors act as alternative IκBs in their own right, thus reinforcing NF-κB inhibition at steady state and upon activation with either selective canonical or non-canonical NF-κB stimuli. These data reveal the complex regulation of NF-κB late in the viral replication cycle, with consequences for both the pathogenesis of HIV/AIDS and the use of NF-κB-modulating drugs in HIV cure strategies. IMPORTANCE The NF-κB pathway regulates host responses to infection and is a common target of viral antagonism. The HIV-1 Vpu protein inhibits NF-κB signaling late in the virus lifecycle, by binding and inhibiting β-TrCP, the substrate recognition portion of the ubiquitin ligase responsible for inducing IκB degradation. Here we demonstrate that Vpu simultaneously inhibits and exploits the two different paralogues of β-TrCP by triggering the degradation of β-TrCP1 and co-opting β-TrCP2 for the destruction of its cellular targets. In so doing, it has a potent inhibitory effect on both the canonical and non-canonical NF-κB pathways. This effect has been underestimated in previous mechanistic studies due to the use of Vpu proteins from lab-adapted viruses. Our findings reveal previously unappreciated differences in the β-TrCP paralogues, revealing functional insights into the regulation of these proteins. This study also raises important implications for the role of NF-κB inhibition in the immunopathogenesis of HIV/AIDS and the way that this may impact on HIV latency reversal strategies based on the activation of the non-canonical NF-κB pathway.
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Affiliation(s)
- Suzanne Pickering
- Department of Infectious Diseases, School of Immunology and Microbial Sciences, King’s College London, London, United Kingdom
| | - Jonathan Sumner
- Department of Infectious Diseases, School of Immunology and Microbial Sciences, King’s College London, London, United Kingdom
| | - Claire Kerridge
- Department of Infectious Diseases, School of Immunology and Microbial Sciences, King’s College London, London, United Kingdom
| | - Marianne Perera
- Department of Infectious Diseases, School of Immunology and Microbial Sciences, King’s College London, London, United Kingdom
| | - Stuart Neil
- Department of Infectious Diseases, School of Immunology and Microbial Sciences, King’s College London, London, United Kingdom
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Marchitto L, Benlarbi M, Prévost J, Laumaea A, Descôteaux-Dinelle J, Medjahed H, Bourassa C, Gendron-Lepage G, Kirchhoff F, Sauter D, Hahn BH, Finzi A, Richard J. Impact of HIV-1 Vpu-mediated downregulation of CD48 on NK-cell-mediated antibody-dependent cellular cytotoxicity. mBio 2023; 14:e0078923. [PMID: 37404017 PMCID: PMC10470595 DOI: 10.1128/mbio.00789-23] [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: 03/28/2023] [Accepted: 05/18/2023] [Indexed: 07/06/2023] Open
Abstract
HIV-1 evades antibody-dependent cellular cytotoxicity (ADCC) responses not only by controlling Env conformation and quantity at the cell surface but also by altering NK cell activation via the downmodulation of several ligands of activating and co-activating NK cell receptors. The signaling lymphocyte activation molecule (SLAM) family of receptors, which includes NTB-A and 2B4, act as co-activating receptors to sustain NK cell activation and cytotoxic responses. These receptors cooperate with CD16 (FcγRIII) and other activating receptors to trigger NK cell effector functions. In that context, Vpu-mediated downregulation of NTB-A on HIV-1-infected CD4 T cells was shown to prevent NK cell degranulation via an homophilic interaction, thus contributing to ADCC evasion. However, less is known on the capacity of HIV-1 to evade 2B4-mediated NK cell activation and ADCC. Here, we show that HIV-1 downregulates the ligand of 2B4, CD48, from the surface of infected cells in a Vpu-dependent manner. This activity is conserved among Vpu proteins from the HIV-1/SIVcpz lineage and depends on conserved residues located in its transmembrane domain and dual phosphoserine motif. We show that NTB-A and 2B4 stimulate CD16-mediated NK cell degranulation and contribute to ADCC responses directed to HIV-1-infected cells to the same extent. Our results suggest that HIV-1 has evolved to downmodulate the ligands of both SLAM receptors to evade ADCC. IMPORTANCE Antibody-dependent cellular cytotoxicity (ADCC) can contribute to the elimination of HIV-1-infected cells and HIV-1 reservoirs. An in-depth understanding of the mechanisms used by HIV-1 to evade ADCC might help develop novel approaches to reduce the viral reservoirs. Members of the signaling lymphocyte activation molecule (SLAM) family of receptors, such as NTB-A and 2B4, play a key role in stimulating NK cell effector functions, including ADCC. Here, we show that Vpu downmodulates CD48, the ligand of 2B4, and this contributes to protect HIV-1-infected cells from ADCC. Our results highlight the importance of the virus to prevent the triggering of the SLAM receptors to evade ADCC.
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Affiliation(s)
- Lorie Marchitto
- Centre de Recherche du CHUM, Montreal, Quebec, Canada
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, Quebec, Canada
| | - Mehdi Benlarbi
- Centre de Recherche du CHUM, Montreal, Quebec, Canada
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, Quebec, Canada
| | - Jérémie Prévost
- Centre de Recherche du CHUM, Montreal, Quebec, Canada
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, Quebec, Canada
| | - Annemarie Laumaea
- Centre de Recherche du CHUM, Montreal, Quebec, Canada
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, Quebec, Canada
| | - Jade Descôteaux-Dinelle
- Centre de Recherche du CHUM, Montreal, Quebec, Canada
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, Quebec, Canada
| | | | | | | | - Frank Kirchhoff
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | - Daniel Sauter
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
- Institute for Medical Virology and Epidemiology of Viral Diseases, University Hospital Tübingen, Tübingen, Germany
| | - Beatrice H. Hahn
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Andrés Finzi
- Centre de Recherche du CHUM, Montreal, Quebec, Canada
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, Quebec, Canada
| | - Jonathan Richard
- Centre de Recherche du CHUM, Montreal, Quebec, Canada
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, Quebec, Canada
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Abstract
The biology of a cell, whether it is a unicellular organism or part of a multicellular network, is influenced by cell type, temporal changes in cell state, and the cell's environment. Spatial cues play a critical role in the regulation of microbial pathogenesis strategies. Information about where the pathogen is-in a tissue or in proximity to a host cell-regulates gene expression and the compartmentalization of gene products in the microbe and the host. Our understanding of host and pathogen identity has bloomed with the accessibility of transcriptomics and proteomics techniques. A missing piece of the puzzle has been our ability to evaluate global transcript and protein expression in the context of the subcellular niche, primary cell, or native tissue environment during infection. This barrier is now lower with the advent of new spatial omics techniques to understand how location regulates cellular functions. This review will discuss how recent advances in spatial proteomics and transcriptomics approaches can address outstanding questions in microbial pathogenesis.
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Affiliation(s)
- Samantha Lempke
- Department of Microbiology, Immunology, and Cancer Biology at the Carter Immunology Center, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Dana May
- Department of Microbiology, Immunology, and Cancer Biology at the Carter Immunology Center, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Sarah E. Ewald
- Department of Microbiology, Immunology, and Cancer Biology at the Carter Immunology Center, University of Virginia School of Medicine, Charlottesville, Virginia, USA
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Judith D, Versapuech M, Bejjani F, Palaric M, Verlhac P, Kuster A, Lepont L, Gallois-Montbrun S, Janvier K, Berlioz-Torrent C. ATG5 selectively engages virus-tethered BST2/tetherin in an LC3C-associated pathway. Proc Natl Acad Sci U S A 2023; 120:e2217451120. [PMID: 37155854 PMCID: PMC10193943 DOI: 10.1073/pnas.2217451120] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 03/15/2023] [Indexed: 05/10/2023] Open
Abstract
Bone marrow stromal antigen 2 (BST2)/tetherin is a restriction factor that reduces HIV-1 dissemination by tethering virus at the cell surface. BST2 also acts as a sensor of HIV-1 budding, establishing a cellular antiviral state. The HIV-1 Vpu protein antagonizes BST2 antiviral functions via multiple mechanisms, including the subversion of an LC3C-associated pathway, a key cell intrinsic antimicrobial mechanism. Here, we describe the first step of this viral-induced LC3C-associated process. This process is initiated at the plasma membrane through the recognition and internalization of virus-tethered BST2 by ATG5, an autophagy protein. ATG5 and BST2 assemble as a complex, independently of the viral protein Vpu and ahead of the recruitment of the ATG protein LC3C. The conjugation of ATG5 with ATG12 is dispensable for this interaction. ATG5 recognizes cysteine-linked homodimerized BST2 and specifically engages phosphorylated BST2 tethering viruses at the plasma membrane, in an LC3C-associated pathway. We also found that this LC3C-associated pathway is used by Vpu to attenuate the inflammatory responses mediated by virion retention. Overall, we highlight that by targeting BST2 tethering viruses, ATG5 acts as a signaling scaffold to trigger an LC3C-associated pathway induced by HIV-1 infection.
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Affiliation(s)
- Delphine Judith
- Université Paris Cité, Institut Cochin, INSERM, CNRS, F-75014Paris, France
| | - Margaux Versapuech
- Université Paris Cité, Institut Cochin, INSERM, CNRS, F-75014Paris, France
| | - Fabienne Bejjani
- Université Paris Cité, Institut Cochin, INSERM, CNRS, F-75014Paris, France
| | - Marjory Palaric
- Université Paris Cité, Institut Cochin, INSERM, CNRS, F-75014Paris, France
| | - Pauline Verlhac
- Université Paris Cité, Institut Cochin, INSERM, CNRS, F-75014Paris, France
| | - Aurelia Kuster
- Université Paris Cité, Institut Cochin, INSERM, CNRS, F-75014Paris, France
| | - Leslie Lepont
- Université Paris Cité, Institut Cochin, INSERM, CNRS, F-75014Paris, France
| | | | - Katy Janvier
- Université Paris Cité, Institut Cochin, INSERM, CNRS, F-75014Paris, France
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Lin X, Ahmad A, Ivanov AI, Simhadri J, Wang S, Kumari N, Ammosova T, Nekhai S. HIV-1 Transcription Inhibitor 1E7-03 Decreases Nucleophosmin Phosphorylation. Mol Cell Proteomics 2023; 22:100488. [PMID: 36563749 PMCID: PMC9975258 DOI: 10.1016/j.mcpro.2022.100488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 12/07/2022] [Accepted: 12/18/2022] [Indexed: 12/25/2022] Open
Abstract
Transcription activation of latent human immunodeficiency virus-1 (HIV-1) occurs due to HIV-1 rebound, the interruption of combination antiretroviral therapy, or development of drug resistance. Thus, novel HIV-1 inhibitors, targeting HIV-1 transcription are needed. We previously developed an HIV-1 transcription inhibitor, 1E7-03, that binds to the noncatalytic RVxF-accommodating site of protein phosphatase 1 and inhibits HIV-1 replication in cultured cells and HIV-1-infected humanized mice by impeding protein phosphatase 1 interaction with HIV-1 Tat protein. However, host proteins and regulatory pathways targeted by 1E7-03 that contribute to its overall HIV-1 inhibitory activity remain to be identified. To address this issue, we performed label-free quantitative proteome and phosphoproteome analyses of noninfected and HIV-1-infected CEM T cells that were untreated or treated with 1E7-03. 1E7-03 significantly reprogramed the phosphorylation profile of proteins including PPARα/RXRα, TGF-β, and PKR pathways. Phosphorylation of nucleophosmin (NPM1) at Ser-125 residue in PPARα/RXRα pathway was significantly reduced (>20-fold, p = 1.37 × 10-9), followed by the reduced phosphorylation of transforming growth factor-beta 2 at Ser-46 (TGF-β2, >12-fold, p = 1.37 × 10-3). Downregulation of NPM1's Ser-125 phosphorylation was further confirmed using Western blot. Phosphorylation mimicking NPM1 S125D mutant activated Tat-induced HIV-1 transcription and exhibited enhanced NPM1-Tat interaction compared to NPM1 S125A mutant. Inhibition of Aurora A or Aurora B kinases that phosphorylate NPM1 on Ser-125 residue inhibited HIV-1, further supporting the role of NPM1 in HIV-1 infection. Taken together, 1E7-03 reprogrammed PPARα/RXRα and TGF-β pathways that contribute to the inhibition of HIV-1 transcription. Our findings suggest that NPM1 phosphorylation is a plausible target for HIV-1 transcription inhibition.
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Key Words
- actn4, alpha-actinin-1
- asl, argininosuccinate lyase
- aspm, abnormal spindle-like microcephaly-associated protein
- cart, combination antiretroviral therapy
- cdk2, cell cycle-dependent kinase 2
- ck2, casein kinase 2
- dmso, dimethyl sulfoxide
- egln1, egl-9 family hypoxia inducible factor 1
- erk/p38, extracellular signal-regulated kinase p38
- fa, formic acid
- gadd34, growth arrest and dna damage-inducible protein
- hif-1α, hypoxia-inducible factor 1α
- hiv-1 vif protein, viral infectivity factor, an hiv-1 accessory protein
- hiv-1, human immunodeficiency virus-1
- hsp90, heat shock protein 90
- ipa, ingenuity pathway analysis
- lc-ft/ms, tandem liquid chromatography-fourier transform mass spectrometry
- mapk, mitogen-activated protein kinase
- map3k4, mitogen-activated protein kinase kinase kinase 4
- mita, mediator of interferon response factor 3 activation
- nfat, nuclear factor of activated t cells
- nf-κb, nuclear factor kappa-light-chain-enhancer of activated b cell
- npm1, nucleophosmin
- oa, okadaic acid
- pi3k/akt, phosphoinositide 3-kinase/ ak strain transforming or protein kinase b
- pp, protein phosphatase
- pparα/rxrα, peroxisome proliferator-activated receptor α/ retinoid x receptor α
- ptm, posttranslational modification
- rnr2, ribonucleotide reductase 2
- rt, reverse transcription
- samhd1, sam domain and hd domain-containing protein 1
- smad7, mothers against decapentaplegic homolog 7
- stat5, signal transducer and activator of transcription 5 taf4
- taf4, transcription factor tfiid subunit tata-box-binding protein (tbp)-associated factor 4
- tgf-β2, transforming growth factor-beta
- tp53, tumor protein p53
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Affiliation(s)
- Xionghao Lin
- Center for Sickle Cell Disease, College of Medicine, Howard University, Washington, District of Columbia, USA; College of Dentistry, Howard University, Washington, District of Columbia, USA
| | - Asrar Ahmad
- Center for Sickle Cell Disease, College of Medicine, Howard University, Washington, District of Columbia, USA
| | - Andrey I Ivanov
- Center for Sickle Cell Disease, College of Medicine, Howard University, Washington, District of Columbia, USA
| | - Jyothirmai Simhadri
- Center for Sickle Cell Disease, College of Medicine, Howard University, Washington, District of Columbia, USA
| | - Songping Wang
- Center for Sickle Cell Disease, College of Medicine, Howard University, Washington, District of Columbia, USA
| | - Namita Kumari
- Center for Sickle Cell Disease, College of Medicine, Howard University, Washington, District of Columbia, USA; Department of Microbiology, College of Medicine, Howard University, Washington, District of Columbia, USA
| | - Tatiana Ammosova
- Center for Sickle Cell Disease, College of Medicine, Howard University, Washington, District of Columbia, USA; Department of Medicine, College of Medicine, Howard University, Washington, District of Columbia, USA
| | - Sergei Nekhai
- Center for Sickle Cell Disease, College of Medicine, Howard University, Washington, District of Columbia, USA; Department of Microbiology, College of Medicine, Howard University, Washington, District of Columbia, USA; Department of Medicine, College of Medicine, Howard University, Washington, District of Columbia, USA.
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7
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Robinson CA, Lyddon TD, Gil HM, Evans DT, Kuzmichev YV, Richard J, Finzi A, Welbourn S, Rasmussen L, Nebane NM, Gupta VV, Ananthan S, Cai Z, Wonderlich ER, Augelli-Szafran CE, Bostwick R, Ptak RG, Schader SM, Johnson MC. Novel Compound Inhibitors of HIV-1 NL4-3 Vpu. Viruses 2022; 14:v14040817. [PMID: 35458546 PMCID: PMC9024541 DOI: 10.3390/v14040817] [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: 03/15/2022] [Revised: 04/06/2022] [Accepted: 04/09/2022] [Indexed: 12/14/2022] Open
Abstract
HIV-1 Vpu targets the host cell proteins CD4 and BST-2/Tetherin for degradation, ultimately resulting in enhanced virus spread and host immune evasion. The discovery and characterization of small molecules that antagonize Vpu would further elucidate the contribution of Vpu to pathogenesis and lay the foundation for the study of a new class of novel HIV-1 therapeutics. To identify novel compounds that block Vpu activity, we have developed a cell-based ‘gain of function’ assay that produces a positive signal in response to Vpu inhibition. To develop this assay, we took advantage of the viral glycoprotein, GaLV Env. In the presence of Vpu, GaLV Env is not incorporated into viral particles, resulting in non-infectious virions. Vpu inhibition restores infectious particle production. Using this assay, a high throughput screen of >650,000 compounds was performed to identify inhibitors that block the biological activity of Vpu. From this screen, we identified several positive hits but focused on two compounds from one structural family, SRI-41897 and SRI-42371. We developed independent counter-screens for off target interactions of the compounds and found no off target interactions. Additionally, these compounds block Vpu-mediated modulation of CD4, BST-2/Tetherin and antibody dependent cell-mediated toxicity (ADCC). Unfortunately, both SRI-41897 and SRI-42371 were shown to be specific to the N-terminal region of NL4-3 Vpu and did not function against other, more clinically relevant, strains of Vpu; however, this assay may be slightly modified to include more significant Vpu strains in the future.
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Affiliation(s)
- Carolyn A. Robinson
- Department of Molecular Microbiology and Immunology, University of Missouri, School of Medicine and the Christopher S. Bond Life Sciences Center, Columbia, MO 65211, USA; (C.A.R.); (T.D.L.); (S.W.)
| | - Terri D. Lyddon
- Department of Molecular Microbiology and Immunology, University of Missouri, School of Medicine and the Christopher S. Bond Life Sciences Center, Columbia, MO 65211, USA; (C.A.R.); (T.D.L.); (S.W.)
| | - Hwi Min Gil
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, WI 53705, USA; (H.M.G.); (D.T.E.)
| | - David T. Evans
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, WI 53705, USA; (H.M.G.); (D.T.E.)
| | - Yury V. Kuzmichev
- Infectious Disease Research, Drug Development Division, Southern Research, Frederick, MD 21701, USA; (Y.V.K.); (Z.C.); (E.R.W.); (R.G.P.); (S.M.S.)
| | - Jonathan Richard
- Centre de Recherche du CHUM, Montréal, QC HX2 0A9, Canada; (J.R.); (A.F.)
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montréal, QC HX2 0A9, Canada
| | - Andrés Finzi
- Centre de Recherche du CHUM, Montréal, QC HX2 0A9, Canada; (J.R.); (A.F.)
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montréal, QC HX2 0A9, Canada
| | - Sarah Welbourn
- Department of Molecular Microbiology and Immunology, University of Missouri, School of Medicine and the Christopher S. Bond Life Sciences Center, Columbia, MO 65211, USA; (C.A.R.); (T.D.L.); (S.W.)
| | - Lynn Rasmussen
- High-Throughput Screening Center, Drug Discovery Division, Southern Research, Birmingham, AL 35205, USA; (L.R.); (N.M.N.); (R.B.)
| | - N. Miranda Nebane
- High-Throughput Screening Center, Drug Discovery Division, Southern Research, Birmingham, AL 35205, USA; (L.R.); (N.M.N.); (R.B.)
| | - Vandana V. Gupta
- Department of Chemistry, Drug Discovery Division, Southern Research, Birmingham, AL 35205, USA; (V.V.G.); (S.A.); (C.E.A.-S.)
| | - Sam Ananthan
- Department of Chemistry, Drug Discovery Division, Southern Research, Birmingham, AL 35205, USA; (V.V.G.); (S.A.); (C.E.A.-S.)
| | - Zhaohui Cai
- Infectious Disease Research, Drug Development Division, Southern Research, Frederick, MD 21701, USA; (Y.V.K.); (Z.C.); (E.R.W.); (R.G.P.); (S.M.S.)
| | - Elizabeth R. Wonderlich
- Infectious Disease Research, Drug Development Division, Southern Research, Frederick, MD 21701, USA; (Y.V.K.); (Z.C.); (E.R.W.); (R.G.P.); (S.M.S.)
| | - Corinne E. Augelli-Szafran
- Department of Chemistry, Drug Discovery Division, Southern Research, Birmingham, AL 35205, USA; (V.V.G.); (S.A.); (C.E.A.-S.)
| | - Robert Bostwick
- High-Throughput Screening Center, Drug Discovery Division, Southern Research, Birmingham, AL 35205, USA; (L.R.); (N.M.N.); (R.B.)
| | - Roger G. Ptak
- Infectious Disease Research, Drug Development Division, Southern Research, Frederick, MD 21701, USA; (Y.V.K.); (Z.C.); (E.R.W.); (R.G.P.); (S.M.S.)
| | - Susan M. Schader
- Infectious Disease Research, Drug Development Division, Southern Research, Frederick, MD 21701, USA; (Y.V.K.); (Z.C.); (E.R.W.); (R.G.P.); (S.M.S.)
| | - Marc C. Johnson
- Department of Molecular Microbiology and Immunology, University of Missouri, School of Medicine and the Christopher S. Bond Life Sciences Center, Columbia, MO 65211, USA; (C.A.R.); (T.D.L.); (S.W.)
- Correspondence:
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Prévost J, Richard J, Gasser R, Medjahed H, Kirchhoff F, Hahn BH, Kappes JC, Ochsenbauer C, Duerr R, Finzi A. Detection of the HIV-1 Accessory Proteins Nef and Vpu by Flow Cytometry Represents a New Tool to Study Their Functional Interplay within a Single Infected CD4 + T Cell. J Virol 2022; 96:e0192921. [PMID: 35080425 PMCID: PMC8941894 DOI: 10.1128/jvi.01929-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 01/16/2022] [Indexed: 11/20/2022] Open
Abstract
The HIV-1 Nef and Vpu accessory proteins are known to protect infected cells from antibody-dependent cellular cytotoxicity (ADCC) responses by limiting exposure of CD4-induced (CD4i) envelope (Env) epitopes at the cell surface. Although both proteins target the host receptor CD4 for degradation, the extent of their functional redundancy is unknown. Here, we developed an intracellular staining technique that permits the intracellular detection of both Nef and Vpu in primary CD4+ T cells by flow cytometry. Using this method, we show that the combined expression of Nef and Vpu predicts the susceptibility of HIV-1-infected primary CD4+ T cells to ADCC by HIV+ plasma. We also show that Vpu cannot compensate for the absence of Nef, thus providing an explanation for why some infectious molecular clones that carry a LucR reporter gene upstream of Nef render infected cells more susceptible to ADCC responses. Our method thus represents a new tool to dissect the biological activity of Nef and Vpu in the context of other host and viral proteins within single infected CD4+ T cells. IMPORTANCE HIV-1 Nef and Vpu exert several biological functions that are important for viral immune evasion, release, and replication. Here, we developed a new method allowing simultaneous detection of these accessory proteins in their native form together with some of their cellular substrates. This allowed us to show that Vpu cannot compensate for the lack of a functional Nef, which has implications for studies that use Nef-defective viruses to study ADCC responses.
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Affiliation(s)
- Jérémie Prévost
- Centre de Recherche du CHUM, Montreal, Quebec, Canada
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, Quebec, Canada
| | - Jonathan Richard
- Centre de Recherche du CHUM, Montreal, Quebec, Canada
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, Quebec, Canada
| | - Romain Gasser
- Centre de Recherche du CHUM, Montreal, Quebec, Canada
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, Quebec, Canada
| | | | - Frank Kirchhoff
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | - Beatrice H. Hahn
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - John C. Kappes
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Christina Ochsenbauer
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Ralf Duerr
- Department of Microbiology, New York University School of Medicine, New York, New York, USA
| | - Andrés Finzi
- Centre de Recherche du CHUM, Montreal, Quebec, Canada
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, Quebec, Canada
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
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Stoneham CA, Langer S, De Jesus PD, Wozniak JM, Lapek J, Deerinck T, Thor A, Pache L, Chanda SK, Gonzalez DJ, Ellisman M, Guatelli J. A combined EM and proteomic analysis places HIV-1 Vpu at the crossroads of retromer and ESCRT complexes: PTPN23 is a Vpu-cofactor. PLoS Pathog 2021; 17:e1009409. [PMID: 34843601 PMCID: PMC8659692 DOI: 10.1371/journal.ppat.1009409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 12/09/2021] [Accepted: 10/08/2021] [Indexed: 11/21/2022] Open
Abstract
The HIV-1 accessory protein Vpu modulates membrane protein trafficking and degradation to provide evasion of immune surveillance. Targets of Vpu include CD4, HLAs, and BST-2. Several cellular pathways co-opted by Vpu have been identified, but the picture of Vpu's itinerary and activities within membrane systems remains incomplete. Here, we used fusion proteins of Vpu and the enzyme ascorbate peroxidase (APEX2) to compare the ultrastructural locations and the proximal proteomes of wild type Vpu and Vpu-mutants. The proximity-omes of the proteins correlated with their ultrastructural locations and placed wild type Vpu near both retromer and ESCRT-0 complexes. Hierarchical clustering of protein abundances across the mutants was essential to interpreting the data and identified Vpu degradation-targets including CD4, HLA-C, and SEC12 as well as Vpu-cofactors including HGS, STAM, clathrin, and PTPN23, an ALIX-like protein. The Vpu-directed degradation of BST-2 was supported by STAM and PTPN23 and to a much lesser extent by the retromer subunits Vps35 and SNX3. PTPN23 also supported the Vpu-directed decrease in CD4 at the cell surface. These data suggest that Vpu directs targets from sorting endosomes to degradation at multi-vesicular bodies via ESCRT-0 and PTPN23.
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Affiliation(s)
- Charlotte A. Stoneham
- Department of Medicine, University of California, San Diego School of Medicine and Veterans Affairs San Diego Healthcare System, La Jolla, California, United States of America
| | - Simon Langer
- Infectious and Inflammatory Disease Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, United States of America
| | - Paul D. De Jesus
- Infectious and Inflammatory Disease Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, United States of America
| | - Jacob M. Wozniak
- Department of Pharmacology, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California, United States of America
| | - John Lapek
- Department of Pharmacology, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California, United States of America
| | - Thomas Deerinck
- National Center for Microscopy and Imaging Research, Center for Research on Biological Systems, University of California, San Diego, School of Medicine, La Jolla, California, United States of America
| | - Andrea Thor
- National Center for Microscopy and Imaging Research, Center for Research on Biological Systems, University of California, San Diego, School of Medicine, La Jolla, California, United States of America
| | - Lars Pache
- Infectious and Inflammatory Disease Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, United States of America
| | - Sumit K. Chanda
- Infectious and Inflammatory Disease Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, United States of America
| | - David J. Gonzalez
- Department of Pharmacology, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California, United States of America
| | - Mark Ellisman
- National Center for Microscopy and Imaging Research, Center for Research on Biological Systems, University of California, San Diego, School of Medicine, La Jolla, California, United States of America
- Department of Neurosciences, University of California, San Diego School of Medicine, La Jolla, California, United States of America
| | - John Guatelli
- Department of Medicine, University of California, San Diego School of Medicine and Veterans Affairs San Diego Healthcare System, La Jolla, California, United States of America
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Abstract
Human immunodeficiency virus (HIV) remodels the cell surface of infected cells to facilitate viral dissemination and promote immune evasion. The membrane-associated viral protein U (Vpu) accessory protein encoded by HIV-1 plays a key role in this process by altering cell surface levels of multiple host proteins. Using an unbiased quantitative plasma membrane profiling approach, we previously identified CD47 as a putative host target downregulated by Vpu. CD47 is a ubiquitously expressed cell surface protein that interacts with the myeloid cell inhibitory receptor signal regulatory protein-alpha (SIRPα) to deliver a "don't-eat-me" signal, thus protecting cells from phagocytosis. In this study, we investigate whether CD47 modulation by HIV-1 Vpu might promote the susceptibility of macrophages to viral infection via phagocytosis of infected CD4+ T cells. Indeed, we find that Vpu downregulates CD47 expression on infected CD4+ T cells, leading to enhanced capture and phagocytosis by macrophages. We further provide evidence that this Vpu-dependent process allows a C-C chemokine receptor type 5 (CCR5)-tropic transmitted/founder (T/F) virus, which otherwise poorly infects macrophages in its cell-free form, to efficiently infect macrophages. Importantly, we show that HIV-1-infected cells expressing a Vpu-resistant CD47 mutant are less prone to infecting macrophages through phagocytosis. Mechanistically, Vpu forms a physical complex with CD47 through its transmembrane domain and targets the latter for lysosomal degradation. These results reveal a novel role of Vpu in modulating macrophage infection, which has important implications for HIV-1 transmission in early stages of infection and the establishment of viral reservoir. IMPORTANCE Macrophages play critical roles in human immunodeficiency virus (HIV) transmission, viral spread early in infection, and as a reservoir of virus. Selective capture and engulfment of HIV-1-infected T cells was shown to drive efficient macrophage infection, suggesting that this mechanism represents an important mode of infection notably for weakly macrophage-tropic T/F viruses. In this study, we provide insight into the signals that regulate this process. We show that the HIV-1 accessory protein viral protein U (Vpu) downregulates cell surface levels of CD47, a host protein that interacts with the inhibitory receptor signal regulatory protein-alpha (SIRPα), to deliver a "don't-eat-me" signal to macrophages. This allows for enhanced capture and phagocytosis of infected T cells by macrophages, ultimately leading to their productive infection even with transmitted/founder (T/F) virus. These findings provide new insights into the mechanisms governing the intercellular transmission of HIV-1 to macrophages with implications for the establishment of the macrophage reservoir and early HIV-1 dissemination in vivo.
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Viral Interactions with Adaptor-Protein Complexes: A Ubiquitous Trait among Viral Species. Int J Mol Sci 2021; 22:ijms22105274. [PMID: 34067854 PMCID: PMC8156722 DOI: 10.3390/ijms22105274] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 05/10/2021] [Accepted: 05/12/2021] [Indexed: 12/22/2022] Open
Abstract
Numerous viruses hijack cellular protein trafficking pathways to mediate cell entry or to rearrange membrane structures thereby promoting viral replication and antagonizing the immune response. Adaptor protein complexes (AP), which mediate protein sorting in endocytic and secretory transport pathways, are one of the conserved viral targets with many viruses possessing AP-interacting motifs. We present here different mechanisms of viral interference with AP complexes and the functional consequences that allow for efficient viral propagation and evasion of host immune defense. The ubiquity of this phenomenon is evidenced by the fact that there are representatives for AP interference in all major viral families, covered in this review. The best described examples are interactions of human immunodeficiency virus and human herpesviruses with AP complexes. Several other viruses, like Ebola, Nipah, and SARS-CoV-2, are pointed out as high priority disease-causative agents supporting the need for deeper understanding of virus-AP interplay which can be exploited in the design of novel antiviral therapies.
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12
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Zapatero-Belinchón FJ, Carriquí-Madroñal B, Gerold G. Proximity labeling approaches to study protein complexes during virus infection. Adv Virus Res 2021; 109:63-104. [PMID: 33934830 DOI: 10.1016/bs.aivir.2021.02.001] [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] [Indexed: 12/20/2022]
Abstract
Cellular compartmentalization of proteins and protein complex formation allow cells to tightly control biological processes. Therefore, understanding the subcellular localization and interactions of a specific protein is crucial to uncover its biological function. The advent of proximity labeling (PL) has reshaped cellular proteomics in infection biology. PL utilizes a genetically modified enzyme that generates a "labeling cloud" by covalently labeling proteins in close proximity to the enzyme. Fusion of a PL enzyme to a specific antibody or a "bait" protein of interest in combination with affinity enrichment mass spectrometry (AE-MS) enables the isolation and identification of the cellular proximity proteome, or proxisome. This powerful methodology has been paramount for the mapping of membrane or membraneless organelles as well as for the understanding of hard-to-purify protein complexes, such as those of transmembrane proteins. Unsurprisingly, more and more infection biology research groups have recognized the potential of PL for the identification of host-pathogen interactions. In this chapter, we introduce the enzymes commonly used for PL labeling as well as recent promising advancements and summarize the major achievements in organelle mapping and nucleic acid PL. Moreover, we comprehensively describe the research on host-pathogen interactions using PL, giving special attention to studies in the field of virology.
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Affiliation(s)
- Francisco José Zapatero-Belinchón
- Department of Biochemistry & Research Center for Emerging Infections and Zoonoses (RIZ), University of Veterinary Medicine Hannover, Hannover, Germany; Institute for Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a Joint Venture Between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany; Department of Clinical Microbiology, Virology, Umeå University, Umeå, Sweden; Wallenberg Centre for Molecular Medicine (WCMM), Umeå University, Umeå, Sweden.
| | - Belén Carriquí-Madroñal
- Department of Biochemistry & Research Center for Emerging Infections and Zoonoses (RIZ), University of Veterinary Medicine Hannover, Hannover, Germany; Institute for Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a Joint Venture Between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany
| | - Gisa Gerold
- Department of Biochemistry & Research Center for Emerging Infections and Zoonoses (RIZ), University of Veterinary Medicine Hannover, Hannover, Germany; Institute for Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a Joint Venture Between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany; Department of Clinical Microbiology, Virology, Umeå University, Umeå, Sweden; Wallenberg Centre for Molecular Medicine (WCMM), Umeå University, Umeå, Sweden.
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13
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Proximity labeling in mammalian cells with TurboID and split-TurboID. Nat Protoc 2020; 15:3971-3999. [PMID: 33139955 DOI: 10.1038/s41596-020-0399-0] [Citation(s) in RCA: 153] [Impact Index Per Article: 38.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Accepted: 08/18/2020] [Indexed: 12/19/2022]
Abstract
This protocol describes the use of TurboID and split-TurboID in proximity labeling applications for mapping protein-protein interactions and subcellular proteomes in live mammalian cells. TurboID is an engineered biotin ligase that uses ATP to convert biotin into biotin-AMP, a reactive intermediate that covalently labels proximal proteins. Optimized using directed evolution, TurboID has substantially higher activity than previously described biotin ligase-related proximity labeling methods, such as BioID, enabling higher temporal resolution and broader application in vivo. Split-TurboID consists of two inactive fragments of TurboID that can be reconstituted through protein-protein interactions or organelle-organelle interactions, which can facilitate greater targeting specificity than full-length enzymes alone. Proteins biotinylated by TurboID or split-TurboID are then enriched with streptavidin beads and identified by mass spectrometry. Here, we describe fusion construct design and characterization (variable timing), proteomic sample preparation (5-7 d), mass spectrometric data acquisition (2 d), and proteomic data analysis (1 week).
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Proulx J, Borgmann K, Park IW. Post-translational modifications inducing proteasomal degradation to counter HIV-1 infection. Virus Res 2020; 289:198142. [PMID: 32882242 DOI: 10.1016/j.virusres.2020.198142] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 08/20/2020] [Accepted: 08/21/2020] [Indexed: 12/14/2022]
Abstract
Post-translational modifications (PTMs) are integral to regulating a wide variety of cellular processes in eukaryotic cells, such as regulation of protein stability, alteration of celluar location, protein activity modulation, and regulation of protein interactions. HIV-1, like other eukaryotic viruses, and its infected host exploit the proteasomal degradation system for their respective proliferation and survival, using various PTMs, including but not limited to ubiquitination, SUMOylation, NEDDylation, interferon-stimulated gene (ISG)ylation. Essentially all viral proteins within the virions -- and in the HIV-1-infected cells -- interact with their cellular counterparts for this degradation, utilizing ubiquitin (Ub), and the Ub-like (Ubl) modifiers less frequently, to eliminate the involved proteins throughout the virus life cycle, from the entry step to release of the assembled virus particles. Such interplay is pivotal for, on the one hand, the cell to restrict proliferation of the infecting virus, and on the other, for molecular counteraction by the virus to overcome this cellular protein-imposed restriction. Recent reports indicate that not only viral/cellular proteins but also viral/viral protein interactions play vital roles in regulating viral protein stability. We hence give an overview of the molecular processes of PTMs involved in proteasomal degradation of the viral and cellular proteins, and the viral/viral and viral/cellular protein interplay in restriction and competition for HIV-1 vs. host cell survival. Insights in this realm could open new avenues for developing therapeutics against HIV-1 via targeting specific steps of the proteasome degradation pathway during the HIV-1 life cycle.
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Affiliation(s)
- Jessica Proulx
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, 76107, United States
| | - Kathleen Borgmann
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, 76107, United States
| | - In-Woo Park
- Microbiology, Immunology, and Genetics, University of North Texas Health Science Center, Fort Worth, TX, 76107, United States.
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15
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Hopfensperger K, Richard J, Stürzel CM, Bibollet-Ruche F, Apps R, Leoz M, Plantier JC, Hahn BH, Finzi A, Kirchhoff F, Sauter D. Convergent Evolution of HLA-C Downmodulation in HIV-1 and HIV-2. mBio 2020; 11:e00782-20. [PMID: 32665270 PMCID: PMC7360927 DOI: 10.1128/mbio.00782-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 06/11/2020] [Indexed: 12/13/2022] Open
Abstract
HLA-C-mediated antigen presentation induces the killing of human immunodeficiency virus (HIV)-infected CD4+ T cells by cytotoxic T lymphocytes (CTLs). To evade killing, many HIV-1 group M strains decrease HLA-C surface levels using their accessory protein Vpu. However, some HIV-1 group M isolates lack this activity, possibly to prevent the activation of natural killer (NK) cells. Analyzing diverse primate lentiviruses, we found that Vpu-mediated HLA-C downregulation is not limited to pandemic group M but is also found in HIV-1 groups O and P as well as several simian immunodeficiency viruses (SIVs). We show that Vpu targets HLA-C primarily at the protein level, independently of its ability to suppress NF-κB-driven gene expression, and that in some viral lineages, HLA-C downregulation may come at the cost of efficient counteraction of the restriction factor tetherin. Remarkably, HIV-2, which does not carry a vpu gene, uses its accessory protein Vif to decrease HLA-C surface expression. This Vif activity requires intact binding sites for the Cullin5/Elongin ubiquitin ligase complex but is separable from its ability to counteract APOBEC3G. Similar to HIV-1 Vpu, the degree of HIV-2 Vif-mediated HLA-C downregulation varies considerably among different virus isolates. In agreement with opposing selection pressures in vivo, we show that the reduction of HLA-C surface levels by HIV-2 Vif is accompanied by increased NK cell-mediated killing. In summary, our results highlight the complex role of HLA-C in lentiviral infections and demonstrate that HIV-1 and HIV-2 have evolved at least two independent mechanisms to decrease HLA-C levels on infected cells.IMPORTANCE Genome-wide association studies suggest that HLA-C expression is a major determinant of viral load set points and CD4+ T cell counts in HIV-infected individuals. On the one hand, efficient HLA-C expression enables the killing of infected cells by cytotoxic T lymphocytes (CTLs). On the other hand, HLA-C sends inhibitory signals to natural killer (NK) cells and enhances the infectivity of newly produced HIV particles. HIV-1 group M viruses modulate HLA-C expression using the accessory protein Vpu, possibly to balance CTL- and NK cell-mediated immune responses. Here, we show that the second human immunodeficiency virus, HIV-2, can use its accessory protein Vif to evade HLA-C-mediated restriction. Furthermore, our mutational analyses provide insights into the underlying molecular mechanisms. In summary, our results reveal how the two human AIDS viruses modulate HLA-C, a key component of the antiviral immune response.
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Affiliation(s)
| | - Jonathan Richard
- Centre de Recherche du CHUM, Montreal, Canada
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, Canada
| | - Christina M Stürzel
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | - Frederic Bibollet-Ruche
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Richard Apps
- NIH Center for Human Immunology, National Institutes of Health, Bethesda, Maryland, USA
| | - Marie Leoz
- Normandie Université, UNIROUEN, UNICAEN, GRAM 2.0, Rouen, France
| | - Jean-Christophe Plantier
- Normandie Université, UNIROUEN, UNICAEN, GRAM 2.0, Rouen University Hospital, Department of Virology, Laboratory Associated with the National Reference Center on HIV, Rouen, France
| | - Beatrice H Hahn
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Andrés Finzi
- Centre de Recherche du CHUM, Montreal, Canada
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, Canada
- Department of Microbiology and Immunology, McGill University, Montreal, Canada
| | - Frank Kirchhoff
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | - Daniel Sauter
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
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16
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Identification of Host Trafficking Genes Required for HIV-1 Virological Synapse Formation in Dendritic Cells. J Virol 2020; 94:JVI.01597-19. [PMID: 32075937 PMCID: PMC7163131 DOI: 10.1128/jvi.01597-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 02/04/2020] [Indexed: 01/15/2023] Open
Abstract
The lentivirus human immunodeficiency virus (HIV) targets and destroys CD4+ T cells, leaving the host vulnerable to life-threatening opportunistic infections associated with AIDS. Dendritic cells (DCs) form a virological synapse (VS) with CD4+ T cells, enabling the efficient transfer of virus between the two cells. We have identified cellular factors that are critical in the induction of the VS. We show that ADP-ribosylation factor 1 (ARF1), bridging integrator 1 (BIN1), and Rab GTPases RAB7L1 and RAB8A are important regulators of HIV-1 trafficking to the VS and therefore the infection of CD4+ T cells. We found these cellular factors were essential for endosomal protein trafficking and formation of the VS and that depletion of target proteins prevented virus trafficking to the plasma membrane by retaining virus in intracellular vesicles. Identification of key regulators in HIV-1 trans-infection between DC and CD4+ T cells has the potential for the development of targeted therapy to reduce trans-infection of HIV-1 in vivo. Dendritic cells (DCs) are one of the earliest targets of HIV-1 infection acting as a “Trojan horse,” concealing the virus from the innate immune system and delivering it to T cells via virological synapses (VS). To explicate how the virus is trafficked through the cell to the VS and evades degradation, a high-throughput small interfering RNA screen targeting membrane trafficking proteins was performed in monocyte-derived DCs. We identified several proteins including BIN-1 and RAB7L1 that share common roles in transport from endosomal compartments. Depletion of target proteins resulted in an accumulation of virus in intracellular compartments and significantly reduced viral trans-infection via the VS. By targeting endocytic trafficking and retromer recycling to the plasma membrane, we were able to reduce the virus’s ability to accumulate at budding microdomains and the VS. Thus, we identify key genes involved in a pathway within DCs that is exploited by HIV-1 to traffic to the VS. IMPORTANCE The lentivirus human immunodeficiency virus (HIV) targets and destroys CD4+ T cells, leaving the host vulnerable to life-threatening opportunistic infections associated with AIDS. Dendritic cells (DCs) form a virological synapse (VS) with CD4+ T cells, enabling the efficient transfer of virus between the two cells. We have identified cellular factors that are critical in the induction of the VS. We show that ADP-ribosylation factor 1 (ARF1), bridging integrator 1 (BIN1), and Rab GTPases RAB7L1 and RAB8A are important regulators of HIV-1 trafficking to the VS and therefore the infection of CD4+ T cells. We found these cellular factors were essential for endosomal protein trafficking and formation of the VS and that depletion of target proteins prevented virus trafficking to the plasma membrane by retaining virus in intracellular vesicles. Identification of key regulators in HIV-1 trans-infection between DC and CD4+ T cells has the potential for the development of targeted therapy to reduce trans-infection of HIV-1 in vivo.
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17
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Prévost J, Edgar CR, Richard J, Trothen SM, Jacob RA, Mumby MJ, Pickering S, Dubé M, Kaufmann DE, Kirchhoff F, Neil SJD, Finzi A, Dikeakos JD. HIV-1 Vpu Downregulates Tim-3 from the Surface of Infected CD4 + T Cells. J Virol 2020; 94:e01999-19. [PMID: 31941771 PMCID: PMC7081912 DOI: 10.1128/jvi.01999-19] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 01/12/2020] [Indexed: 01/26/2023] Open
Abstract
Along with other immune checkpoints, T cell immunoglobulin and mucin domain-containing protein 3 (Tim-3) is expressed on exhausted CD4+ and CD8+ T cells and is upregulated on the surface of these cells upon infection by human immunodeficiency virus type 1 (HIV-1). Recent reports have suggested an antiviral role for Tim-3. However, the molecular determinants of HIV-1 which modulate cell surface Tim-3 levels have yet to be determined. Here, we demonstrate that HIV-1 Vpu downregulates Tim-3 from the surface of infected primary CD4+ T cells, thus attenuating HIV-1-induced upregulation of Tim-3. We also provide evidence that the transmembrane domain of Vpu is required for Tim-3 downregulation. Using immunofluorescence microscopy, we determined that Vpu is in close proximity to Tim-3 and alters its subcellular localization by directing it to Rab 5-positive (Rab 5+) vesicles and targeting it for sequestration within the trans- Golgi network (TGN). Intriguingly, Tim-3 knockdown and Tim-3 blockade increased HIV-1 replication in primary CD4+ T cells, thereby suggesting that Tim-3 expression might represent a natural immune mechanism limiting viral spread.IMPORTANCE HIV infection modulates the surface expression of Tim-3, but the molecular determinants remain poorly understood. Here, we show that HIV-1 Vpu downregulates Tim-3 from the surface of infected primary CD4+ T cells through its transmembrane domain and alters its subcellular localization. Tim-3 blockade increases HIV-1 replication, suggesting a potential negative role of this protein in viral spread that is counteracted by Vpu.
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Affiliation(s)
- Jérémie Prévost
- Centre de Recherche du CHUM, Montreal, Quebec, Canada
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, Quebec, Canada
| | - Cassandra R Edgar
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Jonathan Richard
- Centre de Recherche du CHUM, Montreal, Quebec, Canada
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, Quebec, Canada
| | - Steven M Trothen
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Rajesh Abraham Jacob
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Mitchell J Mumby
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Suzanne Pickering
- Department of Infectious Disease, King's College London School of Life Sciences and Medicine, Guy's Hospital, London, United Kingdom
| | - Mathieu Dubé
- Centre de Recherche du CHUM, Montreal, Quebec, Canada
| | - Daniel E Kaufmann
- Centre de Recherche du CHUM, Montreal, Quebec, Canada
- Department of Medicine, Université de Montréal, Montreal, Quebec, Canada
| | - Frank Kirchhoff
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | - Stuart J D Neil
- Department of Infectious Disease, King's College London School of Life Sciences and Medicine, Guy's Hospital, London, United Kingdom
| | - Andrés Finzi
- Centre de Recherche du CHUM, Montreal, Quebec, Canada
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, Quebec, Canada
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
| | - Jimmy D Dikeakos
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
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Ramirez PW, Sharma S, Singh R, Stoneham CA, Vollbrecht T, Guatelli J. Plasma Membrane-Associated Restriction Factors and Their Counteraction by HIV-1 Accessory Proteins. Cells 2019; 8:E1020. [PMID: 31480747 PMCID: PMC6770538 DOI: 10.3390/cells8091020] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 08/29/2019] [Accepted: 08/30/2019] [Indexed: 02/07/2023] Open
Abstract
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.
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Affiliation(s)
- Peter W Ramirez
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
- VA San Diego Healthcare System, San Diego, CA 92161, USA
| | - Shilpi Sharma
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
- VA San Diego Healthcare System, San Diego, CA 92161, USA
| | - Rajendra Singh
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
- VA San Diego Healthcare System, San Diego, CA 92161, USA
| | - Charlotte A Stoneham
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
- VA San Diego Healthcare System, San Diego, CA 92161, USA
| | - Thomas Vollbrecht
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
- VA San Diego Healthcare System, San Diego, CA 92161, USA
| | - John Guatelli
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA.
- VA San Diego Healthcare System, San Diego, CA 92161, USA.
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19
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Buffalo CZ, Stürzel CM, Heusinger E, Kmiec D, Kirchhoff F, Hurley JH, Ren X. Structural Basis for Tetherin Antagonism as a Barrier to Zoonotic Lentiviral Transmission. Cell Host Microbe 2019; 26:359-368.e8. [PMID: 31447307 DOI: 10.1016/j.chom.2019.08.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 07/05/2019] [Accepted: 07/31/2019] [Indexed: 12/25/2022]
Abstract
Tetherin is a host defense factor that physically prevents virion release from the plasma membrane. The Nef accessory protein of simian immunodeficiency virus (SIV) engages the clathrin adaptor AP-2 to downregulate tetherin via its DIWK motif. As human tetherin lacks DIWK, antagonism of tetherin by Nef is a barrier to simian-human transmission of non-human primate lentiviruses. To determine the molecular basis for tetherin counteraction, we reconstituted the AP-2 complex with a simian tetherin and SIV Nef and determined its structure by cryoelectron microscopy (cryo-EM). Nef refolds the first α-helix of the β2 subunit of AP-2 to a β hairpin, creating a binding site for the DIWK sequence. The tetherin binding site in Nef is distinct from those of most other Nef substrates, including MHC class I, CD3, and CD4 but overlaps with the site for the restriction factor SERINC5. This structure explains the dependence of SIVs on tetherin DIWK and consequent barrier to human transmission.
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Affiliation(s)
- Cosmo Z Buffalo
- Department of Molecular and Cell Biology and California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Christina M Stürzel
- Institute of Molecular Virology, Ulm University Medical Center, 89081 Ulm, Germany
| | - Elena Heusinger
- Institute of Molecular Virology, Ulm University Medical Center, 89081 Ulm, Germany
| | - Dorota Kmiec
- Institute of Molecular Virology, Ulm University Medical Center, 89081 Ulm, Germany
| | - Frank Kirchhoff
- Institute of Molecular Virology, Ulm University Medical Center, 89081 Ulm, Germany
| | - James H Hurley
- Department of Molecular and Cell Biology and California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA; Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
| | - Xuefeng Ren
- Department of Molecular and Cell Biology and California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA.
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20
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Rojas VK, Park IW. Role of the Ubiquitin Proteasome System (UPS) in the HIV-1 Life Cycle. Int J Mol Sci 2019; 20:ijms20122984. [PMID: 31248071 PMCID: PMC6628307 DOI: 10.3390/ijms20122984] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 06/10/2019] [Accepted: 06/11/2019] [Indexed: 01/18/2023] Open
Abstract
Given that the ubiquitin proteasome system (UPS) is the major protein degradation process in the regulation of a wide variety of cellular processes in eukaryotic cells, including alteration of cellular location, modulation of protein activity, and regulation of protein interaction, it is reasonable to suggest that the infecting HIV-1 and the invaded hosts exploit the UPS in a contest for survival and proliferation. However, to date, regulation of the HIV-1 life cycle has been mainly explained by the stage-specific expression of HIV-1 viral genes, not by elimination processes of the synthesized proteins after completion of their duties in the infected cells, which is also quintessential for understanding the molecular processes of the virus life cycle and thereby HIV-1 pathogenesis. In fact, several previous publications have indicated that the UPS plays a critical role in the regulation of the proteasomal degradation of viral and cellular counterparts at every step of the HIV-1 life cycle, from the virus entry to release of the assembled virus particles, which is integral for the regulation of survival and proliferation of the infecting HIV-1 and to replication restriction of the invading virus in the host. However, it is unknown whether and how these individual events taking place at different stages of the HIV-1 life cycle are orchestrated as an overall strategy to overcome the restrictions conferred by the host cells. Thus, in this review, we overview the interplay between HIV-1 viral and cellular proteins for restrictions/competitions for proliferation of the virus in the infected cell, which could open a new avenue for the development of therapeutics against HIV-1 via targeting a specific step of the proteasome degradation pathway during the HIV-1 life cycle.
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Affiliation(s)
- Vivian K Rojas
- Department of Microbiology, Immunology, and Genetics, University of North Texas, Health Science Center, Fort Worth, TX 76107, USA.
| | - In-Woo Park
- Department of Microbiology, Immunology, and Genetics, University of North Texas, Health Science Center, Fort Worth, TX 76107, USA.
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21
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Prévost J, Pickering S, Mumby MJ, Medjahed H, Gendron-Lepage G, Delgado GG, Dirk BS, Dikeakos JD, Stürzel CM, Sauter D, Kirchhoff F, Bibollet-Ruche F, Hahn BH, Dubé M, Kaufmann DE, Neil SJD, Finzi A, Richard J. 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; 10:e01113-19. [PMID: 31213558 PMCID: PMC6581860 DOI: 10.1128/mbio.01113-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 05/09/2019] [Indexed: 01/03/2023] Open
Abstract
The 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.IMPORTANCE The 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.
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Affiliation(s)
- Jérémie Prévost
- Centre de Recherche du CHUM, Montreal, Quebec, Canada
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, Québec, Canada
| | - Suzanne Pickering
- Department of Infectious Disease, King's College London School of Life Sciences and Medicine, Guy's Hospital, London, United Kingdom
| | - Mitchell J Mumby
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada
| | | | | | | | - Brennan S Dirk
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada
| | - Jimmy D Dikeakos
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada
| | - Christina M Stürzel
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | - Daniel Sauter
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | - Frank Kirchhoff
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | - Frederic Bibollet-Ruche
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Beatrice H Hahn
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Mathieu Dubé
- Centre de Recherche du CHUM, Montreal, Quebec, Canada
| | - Daniel E Kaufmann
- Centre de Recherche du CHUM, Montreal, Quebec, Canada
- Department of Medicine, Université de Montréal, Montreal, Quebec, Canada
- Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery, The Scripps Research Institute, La Jolla, California, USA
| | - Stuart J D Neil
- Department of Infectious Disease, King's College London School of Life Sciences and Medicine, Guy's Hospital, London, United Kingdom
| | - Andrés Finzi
- Centre de Recherche du CHUM, Montreal, Quebec, Canada
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, Québec, Canada
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
| | - Jonathan Richard
- Centre de Recherche du CHUM, Montreal, Quebec, Canada
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, Québec, Canada
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22
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Sharma S, Jafari M, Bangar A, William K, Guatelli J, Lewinski MK. The C-Terminal End of HIV-1 Vpu Has a Clade-Specific Determinant That Antagonizes BST-2 and Facilitates Virion Release. J Virol 2019; 93:e02315-18. [PMID: 30867310 PMCID: PMC6532089 DOI: 10.1128/jvi.02315-18] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Accepted: 03/06/2019] [Indexed: 12/12/2022] Open
Abstract
The cellular protein bone marrow stromal antigen-2 (BST-2)/tetherin acts against a variety of enveloped viruses by restricting their release from the plasma membrane. The HIV-1 accessory protein Vpu counteracts BST-2 by downregulating it from the cell surface and displacing it from virion assembly sites. Previous comparisons of Vpus from transmitted/founder viruses and between viruses isolated during acute and chronic infection led to the identification of a tryptophan at position 76 in Vpu (W76) as a key determinant for the displacement of BST-2 from virion assembly sites. Although present in Vpus from clades B, D, and G, W76 is absent from Vpus from clades A, C, and H. Mutagenesis of the C-terminal region of Vpu from two clade C viruses led to the identification of a conserved LL sequence that is functionally analogous to W76 of clade B. Alanine substitution of these leucines partially impaired virion release. This impairment was even greater when the mutations were combined with mutations of the Vpu β-TrCP binding site, resulting in Vpu proteins that induced high surface levels of BST-2 and reduced the efficiency of virion release to less than that of virus lacking vpu Microscopy confirmed that these C-terminal leucines in clade C Vpu, like W76 in clade B, contribute to virion release by supporting the displacement of BST-2 from virion assembly sites. These results suggest that although encoded differently, the ability of Vpu to displace BST-2 from sites of virion assembly on the plasma membrane is evolutionarily conserved among clade B and C HIV-1 isolates.IMPORTANCE Although targeted by a variety of restriction mechanisms, HIV-1 establishes chronic infection in most cases, in part due to the counteraction of these host defenses by viral accessory proteins. Using conserved motifs, the accessory proteins exploit the cellular machinery to degrade or mistraffic host restriction factors, thereby counteracting them. The Vpu protein counteracts the virion-tethering factor BST-2 in part by displacing it from virion assembly sites along the plasma membrane, but a previously identified determinant of that activity is clade specific at the level of protein sequence and not found in the clade C viruses that dominate the pandemic. Here, we show that clade C Vpu provides this activity via a leucine-containing sequence rather than the tryptophan-containing sequence found in clade B Vpu. This difference seems likely to reflect the different evolutionary paths taken by clade B and clade C HIV-1 in human populations.
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Affiliation(s)
- Shilpi Sharma
- Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Moein Jafari
- Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Amandip Bangar
- Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Karen William
- Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - John Guatelli
- Department of Medicine, University of California San Diego, La Jolla, California, USA
- VA San Diego Healthcare System, San Diego, California, USA
| | - Mary K Lewinski
- Department of Medicine, University of California San Diego, La Jolla, California, USA
- VA San Diego Healthcare System, San Diego, California, USA
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23
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Contribution of the Cytoplasmic Determinants of Vpu to the Expansion of Virus-Containing Compartments in HIV-1-Infected Macrophages. J Virol 2019; 93:JVI.00020-19. [PMID: 30867316 DOI: 10.1128/jvi.00020-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 03/09/2019] [Indexed: 12/30/2022] Open
Abstract
HIV-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 E59XXXLV64 and 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.IMPORTANCE HIV-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.
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24
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Morris KL, Buffalo CZ, Stürzel CM, Heusinger E, Kirchhoff F, Ren X, Hurley JH. HIV-1 Nefs Are Cargo-Sensitive AP-1 Trimerization Switches in Tetherin Downregulation. Cell 2019; 174:659-671.e14. [PMID: 30053425 DOI: 10.1016/j.cell.2018.07.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 04/27/2018] [Accepted: 07/03/2018] [Indexed: 01/08/2023]
Abstract
The HIV accessory protein Nef counteracts immune defenses by subverting coated vesicle pathways. The 3.7 Å cryo-EM structure of a closed trimer of the clathrin adaptor AP-1, the small GTPase Arf1, HIV-1 Nef, and the cytosolic tail of the restriction factor tetherin suggested a mechanism for inactivating tetherin by Golgi retention. The 4.3 Å structure of a mutant Nef-induced dimer of AP-1 showed how the closed trimer is regulated by the dileucine loop of Nef. HDX-MS and mutational analysis were used to show how cargo dynamics leads to alternative Arf1 trimerization, directing Nef targets to be either retained at the trans-Golgi or sorted to lysosomes. Phosphorylation of the NL4-3 M-Nef was shown to regulate AP-1 trimerization, explaining how O-Nefs lacking this phosphosite counteract tetherin but most M-Nefs do not. These observations show how the higher-order organization of a vesicular coat can be allosterically modulated to direct cargoes to distinct fates.
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Affiliation(s)
- Kyle L Morris
- Department of Molecular and Cell Biology and California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Cosmo Z Buffalo
- Department of Molecular and Cell Biology and California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Christina M Stürzel
- Institute of Molecular Virology, Ulm University Medical Center, 89081 Ulm, Germany
| | - Elena Heusinger
- Institute of Molecular Virology, Ulm University Medical Center, 89081 Ulm, Germany
| | - Frank Kirchhoff
- Institute of Molecular Virology, Ulm University Medical Center, 89081 Ulm, Germany
| | - Xuefeng Ren
- Department of Molecular and Cell Biology and California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA.
| | - James H Hurley
- Department of Molecular and Cell Biology and California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA; Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
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25
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Lata S, Mishra R, Banerjea AC. Proteasomal Degradation Machinery: Favorite Target of HIV-1 Proteins. Front Microbiol 2018; 9:2738. [PMID: 30524389 PMCID: PMC6262318 DOI: 10.3389/fmicb.2018.02738] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2018] [Accepted: 10/26/2018] [Indexed: 12/17/2022] Open
Abstract
Proteasomal degradation pathways play a central role in regulating a variety of protein functions by controlling not only their turnover but also the physiological behavior of the cell. This makes it an attractive target for the pathogens, especially viruses which rely on the host cellular machinery for their propagation and pathogenesis. Viruses have evolutionarily developed various strategies to manipulate the host proteasomal machinery thereby creating a cellular environment favorable for their own survival and replication. Human immunodeficiency virus-1 (HIV-1) is one of the most dreadful viruses which has rapidly spread throughout the world and caused high mortality due to its high evolution rate. Here, we review the various mechanisms adopted by HIV-1 to exploit the cellular proteasomal machinery in order to escape the host restriction factors and components of host immune system for supporting its own multiplication, and successfully created an infection.
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Affiliation(s)
- Sneh Lata
- Virology Lab II, National Institute of Immunology, New Delhi, India
| | - Ritu Mishra
- Virology Lab II, National Institute of Immunology, New Delhi, India
| | - Akhil C Banerjea
- Virology Lab II, National Institute of Immunology, New Delhi, India
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26
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βTrCP is Required for HIV-1 Vpu Modulation of CD4, GaLV Env, and BST-2/Tetherin. Viruses 2018; 10:v10100573. [PMID: 30347660 PMCID: PMC6212966 DOI: 10.3390/v10100573] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 10/10/2018] [Accepted: 10/16/2018] [Indexed: 12/27/2022] Open
Abstract
The Human immunodeficiency virus-1 (HIV-1) accessory protein Vpu modulates numerous proteins, including the host proteins CD4 and BST-2/tetherin. Vpu interacts with the Skp, Cullin, F-Box (SCF) ubiquitin ligase through interactions with the F-Box protein βTrCP (1 and/or 2). This interaction is dependent on phosphorylation of S52,56 in Vpu. Mutation of S52,56, or inhibition of the SCF, abolishes most Vpu activity against CD4 and partly reduces activity against BST-2/tetherin. Recently, Vpu has also been reported to interact with the clathrin adapter proteins AP-1 and AP-2, and these interactions were also found to be required for BST-2/tetherin antagonism in an S52,56 -dependent manner. In assays where HIV-1 is pseudotyped with gibbon ape leukemia virus (GaLV Env), Vpu has also been found to prevent GaLV Env from being incorporated into viral particles, but the mechanism for this antagonism is not fully understood. To clarify the role of the βTrCPs in Vpu function we used CRISPR/Cas9 to generate a clonal cell line lacking both βTrCP-1 and -2. Vpu activity against CD4 and GaLV Env was abolished in this cell line, and activity against BST-2/tetherin reduced significantly. Mutation of the S52,56 residues no longer affected Vpu activity against BST-2/tetherin in this cell line. These data suggest that the primary role of the S52,56 residues in antagonism of CD4, GaLV Env, and BST-2/tetherin is to recruit the SCF/βTrCP ubiquitin ligase.
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27
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Chen L, Keppler OT, Schölz C. Post-translational Modification-Based Regulation of HIV Replication. Front Microbiol 2018; 9:2131. [PMID: 30254620 PMCID: PMC6141784 DOI: 10.3389/fmicb.2018.02131] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 08/20/2018] [Indexed: 12/13/2022] Open
Abstract
Human immunodeficiency virus (HIV) relies heavily on the host cellular machinery for production of viral progeny. To exploit cellular proteins for replication and to overcome host factors with antiviral activity, HIV has evolved a set of regulatory and accessory proteins to shape an optimized environment for its replication and to facilitate evasion from the immune system. Several cellular pathways are hijacked by the virus to modulate critical steps during the viral life cycle. Thereby, post-translational modifications (PTMs) of viral and cellular proteins gain increasingly attention as modifying enzymes regulate virtually every step of the viral replication cycle. This review summarizes the current knowledge of HIV-host interactions influenced by PTMs with a special focus on acetylation, ubiquitination, and phosphorylation of proteins linked to cellular signaling and viral replication. Insights into these interactions are surmised to aid development of new intervention strategies.
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Affiliation(s)
- Lin Chen
- Max von Pettenkofer-Institute and Gene Center, Virology, National Reference Center for Retroviruses, Faculty of Medicine, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Oliver T Keppler
- Max von Pettenkofer-Institute and Gene Center, Virology, National Reference Center for Retroviruses, Faculty of Medicine, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Christian Schölz
- Max von Pettenkofer-Institute and Gene Center, Virology, National Reference Center for Retroviruses, Faculty of Medicine, Ludwig-Maximilians-University Munich, Munich, Germany
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28
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Singh R, Stoneham C, Lim C, Jia X, Guenaga J, Wyatt R, Wertheim JO, Xiong Y, Guatelli J. Phosphoserine acidic cluster motifs bind distinct basic regions on the μ subunits of clathrin adaptor protein complexes. J Biol Chem 2018; 293:15678-15690. [PMID: 30135209 DOI: 10.1074/jbc.ra118.003080] [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: 03/22/2018] [Revised: 08/17/2018] [Indexed: 12/14/2022] Open
Abstract
Protein trafficking in the endosomal system involves the recognition of specific signals within the cytoplasmic domains (CDs) of transmembrane proteins by clathrin adaptors. One such signal is the phosphoserine acidic cluster (PSAC), the prototype of which is in the endoprotease furin. How PSACs are recognized by clathrin adaptors has been controversial. We reported previously that HIV-1 Vpu, which modulates cellular immunoreceptors, contains a PSAC that binds to the μ subunits of clathrin adaptor protein (AP) complexes. Here, we show that the CD of furin binds the μ subunits of AP-1 and AP-2 in a phosphorylation-dependent manner. Moreover, we identify a potential PSAC in a cytoplasmic loop of the cellular transmembrane Serinc3, an inhibitor of the infectivity of retroviruses. The two serines within the PSAC of Serinc3 are phosphorylated by casein kinase II and mediate interaction with the μ subunits in vitro The sites of these serines vary among mammals in a manner suggesting host-pathogen conflict, yet the Serinc3 PSAC seems dispensable for anti-HIV activity and for counteraction by HIV-1 Nef. The CDs of Vpu and furin and the PSAC-containing loop of Serinc3 each bind the μ subunit of AP-2 (μ2) with similar affinities, but they appear to utilize different basic regions on μ2. The Serinc3 loop requires a region previously reported to bind the acidic plasma membrane lipid phosphatidylinositol 4,5-bisphosphate. These data suggest that the PSACs within different proteins recognize different basic regions on the μ surface, providing the potential to inhibit the activity of viral proteins without necessarily affecting cellular protein trafficking.
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Affiliation(s)
- Rajendra Singh
- From the Department of Medicine, University of California San Diego, La Jolla, California 92093,
| | - Charlotte Stoneham
- From the Department of Medicine, University of California San Diego, La Jolla, California 92093
| | - Christopher Lim
- the Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06510
| | - Xiaofei Jia
- the Department of Chemistry and Biochemistry, University of Massachusetts, Dartmouth, Massachusetts 02747
| | - Javier Guenaga
- the Department of Immunology and Microbiology, Scripps Research Institute, La Jolla, California 92037, and
| | - Richard Wyatt
- the Department of Immunology and Microbiology, Scripps Research Institute, La Jolla, California 92037, and
| | - Joel O Wertheim
- From the Department of Medicine, University of California San Diego, La Jolla, California 92093
| | - Yong Xiong
- the Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06510
| | - John Guatelli
- From the Department of Medicine, University of California San Diego, La Jolla, California 92093, .,the Veterans Affairs San Diego Healthcare System, San Diego, California 92161
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Abstract
Viroporins are short polypeptides encoded by viruses. These small membrane proteins assemble into oligomers that can permeabilize cellular lipid bilayers, disrupting the physiology of the host to the advantage of the virus. Consequently, efforts during the last few decades have been focused towards the discovery of viroporin channel inhibitors, but in general these have not been successful to produce licensed drugs. Viroporins are also involved in viral pathogenesis by engaging in critical interactions with viral proteins, or disrupting normal host cellular pathways through coordinated interactions with host proteins. These protein-protein interactions (PPIs) may become alternative attractive drug targets for the development of antivirals. In this sense, while thus far most antiviral molecules have targeted viral proteins, focus is moving towards targeting host proteins that are essential for virus replication. In principle, this largely would overcome the problem of resistance, with the possibility of using repositioned existing drugs. The precise role of these PPIs, their strain- and host- specificities, and the structural determination of the complexes involved, are areas that will keep the fields of virology and structural biology occupied for years to come. In the present review, we provide an update of the efforts in the characterization of the main PPIs for most viroporins, as well as the role of viroporins in these PPIs interactions.
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Affiliation(s)
| | - David Bhella
- MRC-University of Glasgow Centre for Virus Research, Glasgow, UK
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30
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Pawlak EN, Dirk BS, Jacob RA, Johnson AL, Dikeakos JD. The HIV-1 accessory proteins Nef and Vpu downregulate total and cell surface CD28 in CD4 + T cells. Retrovirology 2018; 15:6. [PMID: 29329537 PMCID: PMC5767034 DOI: 10.1186/s12977-018-0388-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 12/20/2017] [Indexed: 12/20/2022] Open
Abstract
Background The HIV-1 accessory proteins Nef and Vpu alter cell surface levels of multiple host proteins to modify the immune response and increase viral persistence. Nef and Vpu can downregulate cell surface levels of the co-stimulatory molecule CD28, however the mechanism of this function has not been completely elucidated. Results Here, we provide evidence that Nef and Vpu decrease cell surface and total cellular levels of CD28. Moreover, using inhibitors we implicate the cellular degradation machinery in the downregulation of CD28. We shed light on the mechanisms of CD28 downregulation by implicating the Nef LL165 and DD175 motifs in decreasing cell surface CD28 and Nef DD175 in decreasing total cellular CD28. Moreover, the Vpu LV64 and S52/56 motifs were required for cell surface CD28 downregulation, while, unlike for CD4 downregulation, Vpu W22 was dispensable. The Vpu S52/56 motif was also critical for Vpu-mediated decreases in total CD28 protein level. Finally, the ability of Vpu to downregulate CD28 is conserved between multiple group M Vpu proteins and infection with viruses encoding or lacking Nef and Vpu have differential effects on activation upon stimulation. Conclusions We report that Nef and Vpu downregulate cell surface and total cellular CD28 levels. We identified inhibitors and mutations within Nef and Vpu that disrupt downregulation, shedding light on the mechanisms utilized to downregulate CD28. The conservation and redundancy between the abilities of two HIV-1 proteins to downregulate CD28 highlight the importance of this function, which may contribute to the development of latently infected cells. Electronic supplementary material The online version of this article (10.1186/s12977-018-0388-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Emily N Pawlak
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, Dental Sciences Building, Room 3007J, London, ON, N6A 5C1, Canada
| | - Brennan S Dirk
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, Dental Sciences Building, Room 3007J, London, ON, N6A 5C1, Canada
| | - Rajesh Abraham Jacob
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, Dental Sciences Building, Room 3007J, London, ON, N6A 5C1, Canada
| | - Aaron L Johnson
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, Dental Sciences Building, Room 3007J, London, ON, N6A 5C1, Canada
| | - Jimmy D Dikeakos
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, Dental Sciences Building, Room 3007J, London, ON, N6A 5C1, Canada.
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31
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Foster TL, Pickering S, Neil SJD. Inhibiting the Ins and Outs of HIV Replication: Cell-Intrinsic Antiretroviral Restrictions at the Plasma Membrane. Front Immunol 2018; 8:1853. [PMID: 29354117 PMCID: PMC5758531 DOI: 10.3389/fimmu.2017.01853] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 12/07/2017] [Indexed: 01/01/2023] Open
Abstract
Like all viruses, human immunodeficiency viruses (HIVs) and their primate lentivirus relatives must enter cells in order to replicate and, once produced, new virions need to exit to spread to new targets. These processes require the virus to cross the plasma membrane of the cell twice: once via fusion mediated by the envelope glycoprotein to deliver the viral core into the cytosol; and secondly by ESCRT-mediated scission of budding virions during release. This physical barrier thus presents a perfect location for host antiviral restrictions that target enveloped viruses in general. In this review we will examine the current understanding of innate host antiviral defences that inhibit these essential replicative steps of primate lentiviruses associated with the plasma membrane, the mechanism by which these viruses have adapted to evade such defences, and the role that this virus/host battleground plays in the transmission and pathogenesis of HIV/AIDS.
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Affiliation(s)
- Toshana L Foster
- Department of Infectious Disease, School of Immunology and Microbial Sciences, King's College London, London, United Kingdom
| | - Suzanne Pickering
- Department of Infectious Disease, School of Immunology and Microbial Sciences, King's College London, London, United Kingdom
| | - Stuart J D Neil
- Department of Infectious Disease, School of Immunology and Microbial Sciences, King's College London, London, United Kingdom
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32
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Hijacking of the Ubiquitin/Proteasome Pathway by the HIV Auxiliary Proteins. Viruses 2017; 9:v9110322. [PMID: 29088112 PMCID: PMC5707529 DOI: 10.3390/v9110322] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 10/26/2017] [Accepted: 10/30/2017] [Indexed: 02/08/2023] Open
Abstract
The ubiquitin-proteasome system (UPS) ensures regulation of the protein pool in the cell by ubiquitination of proteins followed by their degradation by the proteasome. It plays a central role in the cell under normal physiological conditions as well as during viral infections. On the one hand, the UPS can be used by the cell to degrade viral proteins, thereby restricting the viral infection. On the other hand, it can also be subverted by the virus to its own advantage, notably to induce degradation of cellular restriction factors. This makes the UPS a central player in viral restriction and counter-restriction. In this respect, the human immunodeficiency viruses (HIV-1 and 2) represent excellent examples. Indeed, many steps of the HIV life cycle are restricted by cellular proteins, some of which are themselves components of the UPS. However, HIV itself hijacks the UPS to mediate defense against several cellular restriction factors. For example, the HIV auxiliary proteins Vif, Vpx and Vpu counteract specific restriction factors by the recruitment of cellular UPS components. In this review, we describe the interplay between HIV and the UPS to illustrate its role in the restriction of viral infections and its hijacking by viral proteins for counter-restriction.
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33
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Canonical and Non-Canonical Autophagy in HIV-1 Replication Cycle. Viruses 2017; 9:v9100270. [PMID: 28946621 PMCID: PMC5691622 DOI: 10.3390/v9100270] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Revised: 09/19/2017] [Accepted: 09/21/2017] [Indexed: 12/11/2022] Open
Abstract
Autophagy is a lysosomal-dependent degradative process essential for maintaining cellular homeostasis, and is a key player in innate and adaptive immune responses to intracellular pathogens such as human immunodeficiency virus type 1 (HIV-1). In HIV-1 target cells, autophagy mechanisms can (i) selectively direct viral proteins and viruses for degradation; (ii) participate in the processing and presentation of viral-derived antigens through major histocompatibility complexes; and (iii) contribute to interferon production in response to HIV-1 infection. As a consequence, HIV-1 has evolved different strategies to finely regulate the autophagy pathway to favor its replication and dissemination. HIV-1 notably encodes accessory genes encoding Tat, Nef and Vpu proteins, which are able to perturb and hijack canonical and non-canonical autophagy mechanisms. This review outlines the current knowledge on the complex interplay between autophagy and HIV-1 replication cycle, providing an overview of the autophagy-mediated molecular processes deployed both by infected cells to combat the virus and by HIV-1 to evade antiviral response.
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34
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Stoneham CA, Singh R, Jia X, Xiong Y, Guatelli J. Endocytic activity of HIV-1 Vpu: Phosphoserine-dependent interactions with clathrin adaptors. Traffic 2017; 18:545-561. [PMID: 28504462 DOI: 10.1111/tra.12495] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 05/09/2017] [Accepted: 05/10/2017] [Indexed: 10/19/2022]
Abstract
HIV-1 Vpu modulates cellular transmembrane proteins to optimize viral replication and provide immune-evasion, triggering ubiquitin-mediated degradation of some targets but also modulating endosomal trafficking to deplete them from the plasma membrane. Interactions between Vpu and the heterotetrameric clathrin adaptor protein (AP) complexes AP-1 and AP-2 have been described, yet the molecular basis and functional roles of such interactions are incompletely defined. To investigate the trafficking signals encoded by Vpu, we fused the cytoplasmic domain (CD) of Vpu to the extracellular and transmembrane domains of the CD8 α-chain. CD8-VpuCD was rapidly endocytosed in a clathrin- and AP-2-dependent manner. Multiple determinants within the Vpu CD contributed to endocytic activity, including phosphoserines of the β-TrCP binding site and a leucine-based ExxxLV motif. Using recombinant proteins, we confirmed ExxxLV-dependent binding of the Vpu CD to the α/σ2 subunit hemicomplex of AP-2 and showed that this is enhanced by serine-phosphorylation. Remarkably, the Vpu CD also bound directly to the medium (μ) subunits of AP-2 and AP-1; this interaction was dependent on serine-phosphorylation of Vpu and on basic residues in the μ subunits. We propose that the flexibility with which Vpu binds AP complexes broadens the range of cellular targets that it can misdirect to the virus' advantage.
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Affiliation(s)
- Charlotte A Stoneham
- Department of Medicine, University of California at San Diego, La Jolla, California.,VA San Diego Healthcare System, San Diego, California
| | - Rajendra Singh
- Department of Medicine, University of California at San Diego, La Jolla, California.,VA San Diego Healthcare System, San Diego, California
| | - Xiaofei Jia
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut
| | - Yong Xiong
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut
| | - John Guatelli
- Department of Medicine, University of California at San Diego, La Jolla, California.,VA San Diego Healthcare System, San Diego, California
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35
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HIV-1 Vpu Downmodulates ICAM-1 Expression, Resulting in Decreased Killing of Infected CD4 + T Cells by NK Cells. J Virol 2017; 91:JVI.02442-16. [PMID: 28148794 DOI: 10.1128/jvi.02442-16] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 01/26/2017] [Indexed: 12/20/2022] Open
Abstract
HIV-1 Vpu is known to alter the expression of numerous cell surface molecules. Given the ever-increasing list of Vpu targets identified to date, we undertook a proteomic screen to discover novel cell membrane proteins modulated by this viral protein. Plasma membrane proteome isolates from Vpu-inducible T cells were subjected to stable isotope labeling of amino acids in cell culture (SILAC)-based mass spectrometry analysis, and putative targets were validated by infection of primary CD4+ T cells. We report here that while intercellular adhesion molecule 1 (ICAM-1) and ICAM-3 are upregulated by HIV-1 infection, expression of Vpu offsets this increase by downregulating these molecules from the cell surface. Specifically, we show that Vpu is sufficient to downregulate and deplete ICAM-1 in a manner requiring the Vpu transmembrane domain and a dual-serine (S52/S56) motif necessary for recruitment of the beta-transducin repeat-containing E3 ubiquitin protein ligase (β-TrCP) component of the Skp, Cullin, F-box (SCFβ-TrCP) E3 ubiquitin ligase. Vpu interacts with ICAM-1 to induce its proteasomal degradation. Interestingly, the E3 ubiquitin ligase component β-TrCP-1 is dispensable for ICAM-1 surface downregulation yet is necessary for ICAM-1 degradation. Functionally, Vpu-mediated ICAM-1 downregulation lowers packaging of this adhesion molecule into virions, resulting in decreased infectivity. Importantly, while Vpu-mediated downregulation of ICAM-3 has a limited effect on the conjugation of NK cells to HIV-1-infected CD4+ T cells, downregulation of ICAM-1 by Vpu results in a reduced ability of NK cells to bind and kill infected T cells. Vpu-mediated ICAM-1 downregulation may therefore represent an evolutionary compromise in viral fitness by impeding the formation of cell-to-cell contacts between immune cells and infected T cells at the cost of decreased virion infectivity.IMPORTANCE The major barrier to eradicating HIV-1 infection is the establishment of treatment-resistant reservoirs early in infection. Vpu-mediated ICAM-1 downregulation may contribute to the evasion of cell-mediated immunity during acute infection to promote viral dissemination and the development of viral reservoirs. By aiding the immune system to clear infection prior to the development of reservoirs, novel treatments designed to disrupt Vpu-mediated ICAM-1 downregulation may be beneficial during acute infection or as a prophylactic treatment.
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36
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Roy N, Pacini G, Berlioz-Torrent C, Janvier K. Characterization of E3 ligases involved in lysosomal sorting of the HIV-1 restriction factor BST2. J Cell Sci 2017; 130:1596-1611. [PMID: 28320822 PMCID: PMC5450231 DOI: 10.1242/jcs.195412] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 02/17/2017] [Indexed: 12/17/2022] Open
Abstract
The cellular protein BST2 (also known as tetherin) acts as a major intrinsic antiviral protein that prevents the release of enveloped viruses by trapping nascent viral particles at the surface of infected cells. Viruses have evolved specific strategies to displace BST2 from viral budding sites in order to promote virus egress. In HIV-1, the accessory protein Vpu counters BST2 antiviral activity and promotes sorting of BST2 for lysosomal degradation. Vpu increases polyubiquitylation of BST2, a post-translation modification required for Vpu-induced BST2 downregulation, through recruitment of the E3 ligase complex SCF adaptors β-TrCP1 and β-TrCP2 (two isoforms encoded by BTRC and FBXW11, respectively). Herein, we further investigate the role of the ubiquitylation machinery in the lysosomal sorting of BST2. Using a small siRNA screen, we highlighted two additional regulators of BST2 constitutive ubiquitylation and sorting to the lysosomes: the E3 ubiquitin ligases NEDD4 and MARCH8. Interestingly, Vpu does not hijack the cellular machinery that is constitutively involved in BST2 ubiquitylation to sort BST2 for degradation in the lysosomes but instead promotes the recognition of BST2 by β-TrCP proteins. Altogether, our results provide further understanding of the mechanisms underlying BST2 turnover in cells. Highlighted Article: We identify two E3 ubiquitin ligases, NEDD4 and MARCH8, as regulators of BST2 (tetherin) – a protein that restricts viral release; we thus provide further understanding of the mechanisms underlying BST2 turnover in cells.
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Affiliation(s)
- Nicolas Roy
- Inserm, U1016, Institut Cochin, Paris, France.,CNRS, UMR8104, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Grégory Pacini
- Inserm, U1016, Institut Cochin, Paris, France.,CNRS, UMR8104, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Clarisse Berlioz-Torrent
- Inserm, U1016, Institut Cochin, Paris, France.,CNRS, UMR8104, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Katy Janvier
- Inserm, U1016, Institut Cochin, Paris, France .,CNRS, UMR8104, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, France
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37
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Lukhele S, Cohen ÉA. Conserved residues within the HIV-1 Vpu transmembrane-proximal hinge region modulate BST2 binding and antagonism. Retrovirology 2017; 14:18. [PMID: 28288652 PMCID: PMC5348903 DOI: 10.1186/s12977-017-0345-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 03/05/2017] [Indexed: 11/10/2022] Open
Abstract
Background BST2 inhibits HIV-1 release by tethering nascent virions to the surface of infected cells. HIV-1 Vpu overcomes this restriction by removing BST2 from viral budding sites via BST2 intracellular trapping and sequestration, surface downregulation and/or displacement mechanisms. Vpu is composed of a short luminal tail, a transmembrane domain (TMD) and a cytoplasmic hinge region that is followed by two helices. BST2 counteraction relies on the ability of Vpu to physically bind BST2 through TMD interactions and recruit the clathrin-dependent trafficking machinery via a canonical acidic di-leucine signalling motif within the helix-2 of Vpu. The highly conserved Vpu transmembrane-proximal hinge region encompasses residues that resemble an acidic leucine-based trafficking motif, whose functional roles are currently ill-defined. In this study, we investigated the contribution of these residues towards Vpu-mediated BST2 antagonism. Results We show that while these conserved residues have no intrinsic activity on the cellular distribution of Vpu in the absence of BST2, they regulate the ability of Vpu to bind to BST2 and, consequently, govern both BST2-dependent trafficking properties of the protein as well as its co-localization with BST2. Moreover, these residues, particularly a glutamic acid residue positioned immediately following the TMD, are a determinant not only for efficient targeting of BST2, but also binding and degradation of CD4, another host membrane protein targeted by Vpu. Mechanistically, our data are consistent with a role of these residues in the maintenance of the Vpu TMD conformational configuration such that interactions with membrane-associated host targets are favoured. Conclusions Altogether, this work demonstrates an important regulatory role of the transmembrane-proximal Vpu hinge region residues towards enabling the protein to efficiently engage its target host proteins. Thus, this highly conserved, cytosolic Vpu hinge region may represent an attractive target for the development of anti-Vpu inhibitors. Electronic supplementary material The online version of this article (doi:10.1186/s12977-017-0345-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sabelo Lukhele
- Laboratory of Human Retrovirology, Institut de Recherches Cliniques de Montréal (IRCM), 110, Pine Avenue West, Montreal, QC, H2W 1R7, Canada.,Division of Experimental Medicine, McGill University, Montreal, QC, H3A 1A3, Canada
| | - Éric A Cohen
- Laboratory of Human Retrovirology, Institut de Recherches Cliniques de Montréal (IRCM), 110, Pine Avenue West, Montreal, QC, H2W 1R7, Canada. .,Division of Experimental Medicine, McGill University, Montreal, QC, H3A 1A3, Canada. .,Department of Microbiology, Infectiology and Immunology, Université de Montréal, Montreal, QC, H3T 1J4, Canada.
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38
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Soper A, Juarez-Fernandez G, Aso H, Moriwaki M, Yamada E, Nakano Y, Koyanagi Y, Sato K. Various plus unique: Viral protein U as a plurifunctional protein for HIV-1 replication. Exp Biol Med (Maywood) 2017; 242:850-858. [PMID: 28346011 DOI: 10.1177/1535370217697384] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1), the causative agent of acquired immunodeficiency syndrome, encodes four accessory genes, one of which is viral protein U (Vpu). Recently, the study of Vpu has been of great interest. For instance, various cellular proteins are degraded (e.g. CD4) and down-modulated (e.g. tetherin) by Vpu. Vpu also antagonizes the function of tetherin and inhibits NF-κB. Moreover, Vpu is a viroporin forming ion channels and may represent a promising target for anti-HIV-1 drugs. In this review, we summarize the domains/residues that are responsible for Vpu's functions, describe the current understanding of the role of Vpu in HIV-1-infected cells, and review the effect of Vpu on HIV-1 in replication and pathogenesis. Future investigations that simultaneously assess a combination of Vpu functions are required to clearly delineate the most important functions for viral replication. Impact statement Viral protein U (Vpu) is a unique protein encoded by human immunodeficiency virus type 1 (HIV-1) and related lentiviruses, playing multiple roles in viral replication and pathogenesis. In this review, we briefly summarize the most up-to-date knowledge of HIV-1 Vpu.
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Affiliation(s)
- Andrew Soper
- 1 Laboratory of Systems Virology, Department of Biosystems Science, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 6068507, Japan
| | - Guillermo Juarez-Fernandez
- 1 Laboratory of Systems Virology, Department of Biosystems Science, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 6068507, Japan
| | - Hirofumi Aso
- 1 Laboratory of Systems Virology, Department of Biosystems Science, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 6068507, Japan.,2 Faculty of Pharmaceutical Sciences, Kyoto University, Kyoto 6068501, Japan
| | - Miyu Moriwaki
- 1 Laboratory of Systems Virology, Department of Biosystems Science, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 6068507, Japan.,3 Graduate School of Biostudies, Kyoto University, Kyoto 6068315, Japan
| | - Eri Yamada
- 1 Laboratory of Systems Virology, Department of Biosystems Science, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 6068507, Japan
| | - Yusuke Nakano
- 1 Laboratory of Systems Virology, Department of Biosystems Science, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 6068507, Japan
| | - Yoshio Koyanagi
- 1 Laboratory of Systems Virology, Department of Biosystems Science, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 6068507, Japan
| | - Kei Sato
- 1 Laboratory of Systems Virology, Department of Biosystems Science, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 6068507, Japan.,4 CREST, Japan Science and Technology Agency, Saitama 3220012, Japan
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Differential Control of BST2 Restriction and Plasmacytoid Dendritic Cell Antiviral Response by Antagonists Encoded by HIV-1 Group M and O Strains. J Virol 2016; 90:10236-10246. [PMID: 27581991 DOI: 10.1128/jvi.01131-16] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 08/29/2016] [Indexed: 12/15/2022] Open
Abstract
BST2/tetherin is a type I interferon (IFN-I)-stimulated host factor that restricts the release of HIV-1 by entrapping budding virions at the cell surface. This membrane-associated protein can also engage and activate the plasmacytoid dendritic cell (pDC)-specific immunoglobulin-like transcript 7 (ILT7) inhibitory receptor to downregulate the IFN-I response by pDCs. Pandemic HIV-1 group M uses Vpu (M-Vpu) to counteract the two BST2 isoforms (long and short) that are expressed in human cells. M-Vpu efficiently downregulates surface long BST2, while it displaces short BST2 molecules away from viral assembly sites. We recently found that this attribute is used by M-Vpu to activate the BST2/ILT7-dependent negative-feedback pathway and to suppress pDC IFN-I responses during sensing of infected cells. However, whether this property is conserved in endemic HIV-1 group O, which has evolved Nef (O-Nef) to counteract specifically the long BST2 isoform, remains unknown. In the present study, we validated that O-Nefs have the capacity to downregulate surface BST2 and enhance HIV-1 particle release although less efficiently than M-Vpu. In contrast to M-Vpu, O-Nef did not efficiently enhance viral spread in T cell culture or displace short BST2 from viral assembly sites to prevent its occlusion by tethered HIV-1 particles. Consequently, O-Nef impairs the ability of BST2 to activate negative ILT7 signaling to suppress the IFN-I response by pDC-containing peripheral blood mononuclear cells (PBMCs) during sensing of infected cells. These distinctive features of BST2 counteraction by O-Nefs may in part explain the limited spread of HIV-1 group O in the human population. IMPORTANCE The geographical distributions and prevalences of different HIV-1 groups show large variations. Understanding drivers of distinctive viral spread may aid in the development of therapeutic strategies for controlling the spread of HIV-1 pandemic strains. The differential spread of HIV-1 groups appears to be linked to their capacities to antagonize the long and short isoforms of the BST2 restriction factor. We found that the endemic HIV-1 group O-encoded BST2 antagonist Nef is unable to counteract the restriction mediated by short BST2, a condition that impairs its ability to activate ILT7 and suppress pDC antiviral responses. This is in contrast to the pandemic HIV-1 group M-specified BST2 countermeasure Vpu, which displays a diverse array of mechanisms to counteract short and long BST2 isoforms, an attribute that allows the effective control of pDC antiviral responses. These findings may help explain the limited spread of HIV-1 group O as well as the continued predominance of HIV-1 group M throughout the world.
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40
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Filling the Void: Proximity-Based Labeling of Proteins in Living Cells. Trends Cell Biol 2016; 26:804-817. [PMID: 27667171 DOI: 10.1016/j.tcb.2016.09.004] [Citation(s) in RCA: 186] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 08/30/2016] [Accepted: 09/02/2016] [Indexed: 12/17/2022]
Abstract
There are inherent limitations with traditional methods to study protein behavior or to determine the constituency of proteins in discrete subcellular compartments. In response to these limitations, several methods have recently been developed that use proximity-dependent labeling. By fusing proteins to enzymes that generate reactive molecules, most commonly biotin, proximate proteins are covalently labeled to enable their isolation and identification. In this review we describe current methods for proximity-dependent labeling in living cells and discuss their applications and future use in the study of protein behavior.
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Abstract
The HIV genome encodes a small number of viral proteins (i.e., 16), invariably establishing cooperative associations among HIV proteins and between HIV and host proteins, to invade host cells and hijack their internal machineries. As a known example, the HIV envelope glycoprotein GP120 is closely associated with GP41 for viral entry. From a genome-wide perspective, a hypothesis can be worked out to determine whether 16 HIV proteins could develop 120 possible pairwise associations either by physical interactions or by functional associations mediated via HIV or host molecules. Here, we present the first systematic review of experimental evidence on HIV genome-wide protein associations using a large body of publications accumulated over the past 3 decades. Of 120 possible pairwise associations between 16 HIV proteins, at least 34 physical interactions and 17 functional associations have been identified. To achieve efficient viral replication and infection, HIV protein associations play essential roles (e.g., cleavage, inhibition, and activation) during the HIV life cycle. In either a dispensable or an indispensable manner, each HIV protein collaborates with another viral protein to accomplish specific activities that precisely take place at the proper stages of the HIV life cycle. In addition, HIV genome-wide protein associations have an impact on anti-HIV inhibitors due to the extensive cross talk between drug-inhibited proteins and other HIV proteins. Overall, this study presents for the first time a comprehensive overview of HIV genome-wide protein associations, highlighting meticulous collaborations between all viral proteins during the HIV life cycle.
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Affiliation(s)
- Guangdi Li
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China KU Leuven-University of Leuven, Rega Institute for Medical Research, Department of Microbiology and Immunology, Leuven, Belgium
| | - Erik De Clercq
- KU Leuven-University of Leuven, Rega Institute for Medical Research, Department of Microbiology and Immunology, Leuven, Belgium
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Varnaitė R, MacNeill SA. Meet the neighbors: Mapping local protein interactomes by proximity-dependent labeling with BioID. Proteomics 2016; 16:2503-2518. [PMID: 27329485 PMCID: PMC5053326 DOI: 10.1002/pmic.201600123] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 05/23/2016] [Accepted: 06/16/2016] [Indexed: 12/13/2022]
Abstract
Proximity-dependent biotin identification (BioID) is a recently developed method that allows the identification of proteins in the close vicinity of a protein of interest in living cells. BioID relies on fusion of the protein of interest with a mutant form of the biotin ligase enzyme BirA (BirA*) that is capable of promiscuously biotinylating proximal proteins irrespective of whether these interact directly or indirectly with the fusion protein or are merely located in the same subcellular neighborhood. The covalent addition of biotin allows the labeled proteins to be purified from cell extracts on the basis of their affinity for streptavidin and identified by mass spectrometry. To date, BioID has been successfully applied to study a variety of proteins and processes in mammalian cells and unicellular eukaryotes and has been shown to be particularly suited to the study of insoluble or inaccessible cellular structures and for detecting weak or transient protein associations. Here, we provide an introduction to BioID, together with a detailed summary of where and how the method has been applied to date, and briefly discuss technical aspects involved in the planning and execution of a BioID study.
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Affiliation(s)
- Renata Varnaitė
- School of Biology, University of St Andrews, North Haugh, St Andrews, Scotland, UK
| | - Stuart A MacNeill
- School of Biology, University of St Andrews, North Haugh, St Andrews, Scotland, UK.
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HIV-1 Vpu Antagonizes CD317/Tetherin by Adaptor Protein-1-Mediated Exclusion from Virus Assembly Sites. J Virol 2016; 90:6709-6723. [PMID: 27170757 DOI: 10.1128/jvi.00504-16] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 05/06/2016] [Indexed: 01/22/2023] Open
Abstract
UNLABELLED The 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. IMPORTANCE CD317/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.
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HIV Genome-Wide Protein Associations: a Review of 30 Years of Research. Microbiol Mol Biol Rev 2016; 80:679-731. [PMID: 27357278 DOI: 10.1128/mmbr.00065-15] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The HIV genome encodes a small number of viral proteins (i.e., 16), invariably establishing cooperative associations among HIV proteins and between HIV and host proteins, to invade host cells and hijack their internal machineries. As a known example, the HIV envelope glycoprotein GP120 is closely associated with GP41 for viral entry. From a genome-wide perspective, a hypothesis can be worked out to determine whether 16 HIV proteins could develop 120 possible pairwise associations either by physical interactions or by functional associations mediated via HIV or host molecules. Here, we present the first systematic review of experimental evidence on HIV genome-wide protein associations using a large body of publications accumulated over the past 3 decades. Of 120 possible pairwise associations between 16 HIV proteins, at least 34 physical interactions and 17 functional associations have been identified. To achieve efficient viral replication and infection, HIV protein associations play essential roles (e.g., cleavage, inhibition, and activation) during the HIV life cycle. In either a dispensable or an indispensable manner, each HIV protein collaborates with another viral protein to accomplish specific activities that precisely take place at the proper stages of the HIV life cycle. In addition, HIV genome-wide protein associations have an impact on anti-HIV inhibitors due to the extensive cross talk between drug-inhibited proteins and other HIV proteins. Overall, this study presents for the first time a comprehensive overview of HIV genome-wide protein associations, highlighting meticulous collaborations between all viral proteins during the HIV life cycle.
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45
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Rapiteanu R, Davis LJ, Williamson JC, Timms RT, Paul Luzio J, Lehner PJ. A Genetic Screen Identifies a Critical Role for the WDR81-WDR91 Complex in the Trafficking and Degradation of Tetherin. Traffic 2016; 17:940-58. [PMID: 27126989 PMCID: PMC5025723 DOI: 10.1111/tra.12409] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 04/26/2016] [Accepted: 04/26/2016] [Indexed: 12/24/2022]
Abstract
Tetherin (BST2/CD317) is a viral restriction factor that anchors enveloped viruses to host cells and limits viral spread. The HIV‐1 Vpu accessory protein counteracts tetherin by decreasing its cell surface expression and targeting it for ubiquitin‐dependent endolysosomal degradation. Although the Vpu‐mediated downregulation of tetherin has been extensively studied, the molecular details are not completely elucidated. We therefore used a forward genetic screen in human haploid KBM7 cells to identify novel genes required for tetherin trafficking. Our screen identified WDR81 as a novel gene required for tetherin trafficking and degradation in both the presence and absence of Vpu. WDR81 is a BEACH‐domain containing protein that is also required for the degradation of EGF‐stimulated epidermal growth factor receptor (EGFR) and functions in a complex with the WDR91 protein. In the absence of WDR81 the endolysosomal compartment appears swollen, with enlarged early and late endosomes and reduced delivery of endocytosed dextran to cathepsin‐active lysosomes. Our data suggest a role for the WDR81‐WDR91 complex in the fusion of endolysosomal compartments and the absence of WDR81 leads to impaired receptor trafficking and degradation.
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Affiliation(s)
- Radu Rapiteanu
- Cambridge Institute for Medical Research, University of Cambridge School of Clinical Medicine, Wellcome Trust/MRC Building Biomedical Campus, Cambridge, CB2 0XY, UK
| | - Luther J Davis
- Departments of Medicine and Clinical Biochemistry, University of Cambridge School of Clinical Medicine, Wellcome Trust/MRC Building Biomedical Campus, Cambridge, CB2 0XY, UK
| | - James C Williamson
- Cambridge Institute for Medical Research, University of Cambridge School of Clinical Medicine, Wellcome Trust/MRC Building Biomedical Campus, Cambridge, CB2 0XY, UK
| | - Richard T Timms
- Cambridge Institute for Medical Research, University of Cambridge School of Clinical Medicine, Wellcome Trust/MRC Building Biomedical Campus, Cambridge, CB2 0XY, UK
| | - J Paul Luzio
- Departments of Medicine and Clinical Biochemistry, University of Cambridge School of Clinical Medicine, Wellcome Trust/MRC Building Biomedical Campus, Cambridge, CB2 0XY, UK
| | - Paul J Lehner
- Cambridge Institute for Medical Research, University of Cambridge School of Clinical Medicine, Wellcome Trust/MRC Building Biomedical Campus, Cambridge, CB2 0XY, UK
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Apps R, Del Prete GQ, Chatterjee P, Lara A, Brumme ZL, Brockman MA, Neil S, Pickering S, Schneider DK, Piechocka-Trocha A, Walker BD, Thomas R, Shaw GM, Hahn BH, Keele BF, Lifson JD, Carrington M. HIV-1 Vpu Mediates HLA-C Downregulation. Cell Host Microbe 2016; 19:686-95. [PMID: 27173934 PMCID: PMC4904791 DOI: 10.1016/j.chom.2016.04.005] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Revised: 03/08/2016] [Accepted: 04/05/2016] [Indexed: 12/31/2022]
Abstract
Many pathogens evade cytotoxic T lymphocytes (CTLs) by downregulating HLA molecules on infected cells, but the loss of HLA can trigger NK cell-mediated lysis. HIV-1 is thought to subvert CTLs while preserving NK cell inhibition by Nef-mediated downregulation of HLA-A and -B but not HLA-C molecules. We find that HLA-C is downregulated by most primary HIV-1 clones, including transmitted founder viruses, in contrast to the laboratory-adapted NL4-3 virus. HLA-C reduction is mediated by viral Vpu and reduces the ability of HLA-C restricted CTLs to suppress viral replication in CD4+ cells in vitro. HLA-A/B are unaffected by Vpu, and primary HIV-1 clones vary in their ability to downregulate HLA-C, possibly in response to whether CTLs or NK cells dominate immune pressure through HLA-C. HIV-2 also suppresses HLA-C expression through distinct mechanisms, underscoring the immune pressure HLA-C exerts on HIV. This viral immune evasion casts new light on the roles of CTLs and NK cells in immune responses against HIV.
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Affiliation(s)
- Richard Apps
- Cancer and Inflammation Program, Leidos Biomedical Research, Frederick National Laboratory, Frederick, MD 21702, USA
| | - Gregory Q Del Prete
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Frederick National Laboratory, Frederick, MD 21702, USA
| | - Pramita Chatterjee
- Cancer and Inflammation Program, Leidos Biomedical Research, Frederick National Laboratory, Frederick, MD 21702, USA
| | - Abigail Lara
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Frederick National Laboratory, Frederick, MD 21702, USA
| | - Zabrina L Brumme
- Faculty of Health Sciences, Simon Fraser University, Burnaby, BC V5A 1S6, Canada; British Columbia Centre for Excellence in HIV/AIDS, Vancouver, BC V67 1Y6, Canada
| | - Mark A Brockman
- Faculty of Health Sciences, Simon Fraser University, Burnaby, BC V5A 1S6, Canada; British Columbia Centre for Excellence in HIV/AIDS, Vancouver, BC V67 1Y6, Canada
| | - Stuart Neil
- Department of Infectious Disease, King's College London School of Medicine, Guy's Hospital, London SE1 9RT, UK
| | - Suzanne Pickering
- Department of Infectious Disease, King's College London School of Medicine, Guy's Hospital, London SE1 9RT, UK
| | - Douglas K Schneider
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Frederick National Laboratory, Frederick, MD 21702, USA
| | - Alicja Piechocka-Trocha
- Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology and Harvard University, Cambridge, MA 02139-3583, USA
| | - Bruce D Walker
- Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology and Harvard University, Cambridge, MA 02139-3583, USA
| | - Rasmi Thomas
- Host Genetics Section, US Military HIV Research Program, Silver Spring, MD 20910, USA
| | - George M Shaw
- Departments of Medicine and Microbiology, University of Pennsylvania, Philadelphia, PA 19104-6076, USA
| | - Beatrice H Hahn
- Departments of Medicine and Microbiology, University of Pennsylvania, Philadelphia, PA 19104-6076, USA
| | - Brandon F Keele
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Frederick National Laboratory, Frederick, MD 21702, USA
| | - Jeffrey D Lifson
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Frederick National Laboratory, Frederick, MD 21702, USA
| | - Mary Carrington
- Cancer and Inflammation Program, Leidos Biomedical Research, Frederick National Laboratory, Frederick, MD 21702, USA; Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology and Harvard University, Cambridge, MA 02139-3583, USA.
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Remodeling of the Host Cell Plasma Membrane by HIV-1 Nef and Vpu: A Strategy to Ensure Viral Fitness and Persistence. Viruses 2016; 8:67. [PMID: 26950141 PMCID: PMC4810257 DOI: 10.3390/v8030067] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Revised: 02/09/2016] [Accepted: 02/16/2016] [Indexed: 02/07/2023] Open
Abstract
The plasma membrane protects the cell from its surroundings and regulates cellular communication, homing, and metabolism. Not surprisingly, the composition of this membrane is highly controlled through the vesicular trafficking of proteins to and from the cell surface. As intracellular pathogens, most viruses exploit the host plasma membrane to promote viral replication while avoiding immune detection. This is particularly true for the enveloped human immunodeficiency virus (HIV), which assembles and obtains its lipid shell directly at the plasma membrane. HIV-1 encodes two proteins, negative factor (Nef) and viral protein U (Vpu), which function primarily by altering the quantity and localization of cell surface molecules to increase virus fitness despite host antiviral immune responses. These proteins are expressed at different stages in the HIV-1 life cycle and employ a variety of mechanisms to target both unique and redundant surface proteins, including the viral receptor CD4, host restriction factors, immunoreceptors, homing molecules, tetraspanins and membrane transporters. In this review, we discuss recent progress in the study of the Nef and Vpu targeting of host membrane proteins with an emphasis on how remodeling of the cell membrane allows HIV-1 to avoid host antiviral immune responses leading to the establishment of systemic and persistent infection.
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48
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Kim DI, Jensen SC, Noble KA, Kc B, Roux KH, Motamedchaboki K, Roux KJ. An improved smaller biotin ligase for BioID proximity labeling. Mol Biol Cell 2016; 27:1188-96. [PMID: 26912792 PMCID: PMC4831873 DOI: 10.1091/mbc.e15-12-0844] [Citation(s) in RCA: 504] [Impact Index Per Article: 63.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 02/16/2016] [Indexed: 12/20/2022] Open
Abstract
A smaller promiscuous biotin ligase for proximity biotinylation called BioID2 enables more-selective targeting of fusion proteins, requires less biotin supplementation, exhibits enhanced labeling of proximate proteins, and demonstrates the use of a flexible linker to modulate the biotin-labeling radius. The BioID method uses a promiscuous biotin ligase to detect protein–protein associations as well as proximate proteins in living cells. Here we report improvements to the BioID method centered on BioID2, a substantially smaller promiscuous biotin ligase. BioID2 enables more-selective targeting of fusion proteins, requires less biotin supplementation, and exhibits enhanced labeling of proximate proteins. Thus BioID2 improves the efficiency of screening for protein–protein associations. We also demonstrate that the biotinylation range of BioID2 can be considerably modulated using flexible linkers, thus enabling application-specific adjustment of the biotin-labeling radius.
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Affiliation(s)
- Dae In Kim
- Sanford Children's Health Research Center, Sanford Research, Sioux Falls, SD 57104
| | - Samuel C Jensen
- Sanford Children's Health Research Center, Sanford Research, Sioux Falls, SD 57104
| | - Kyle A Noble
- Department of Biological Science, Florida State University, Tallahassee, FL 32306
| | - Birendra Kc
- Sanford Children's Health Research Center, Sanford Research, Sioux Falls, SD 57104
| | - Kenneth H Roux
- Department of Biological Science, Florida State University, Tallahassee, FL 32306
| | - Khatereh Motamedchaboki
- Sanford-Burnham Proteomics Facility, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037
| | - Kyle J Roux
- Sanford Children's Health Research Center, Sanford Research, Sioux Falls, SD 57104 Department of Pediatrics, Sanford School of Medicine, University of South Dakota, Sioux Falls, SD 57105
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Sobhy H. A Review of Functional Motifs Utilized by Viruses. Proteomes 2016; 4:proteomes4010003. [PMID: 28248213 PMCID: PMC5217368 DOI: 10.3390/proteomes4010003] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 01/07/2016] [Accepted: 01/13/2016] [Indexed: 01/05/2023] Open
Abstract
Short linear motifs (SLiM) are short peptides that facilitate protein function and protein-protein interactions. Viruses utilize these motifs to enter into the host, interact with cellular proteins, or egress from host cells. Studying functional motifs may help to predict protein characteristics, interactions, or the putative cellular role of a protein. In virology, it may reveal aspects of the virus tropism and help find antiviral therapeutics. This review highlights the recent understanding of functional motifs utilized by viruses. Special attention was paid to the function of proteins harboring these motifs, and viruses encoding these proteins. The review highlights motifs involved in (i) immune response and post-translational modifications (e.g., ubiquitylation, SUMOylation or ISGylation); (ii) virus-host cell interactions, including virus attachment, entry, fusion, egress and nuclear trafficking; (iii) virulence and antiviral activities; (iv) virion structure; and (v) low-complexity regions (LCRs) or motifs enriched with residues (Xaa-rich motifs).
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Affiliation(s)
- Haitham Sobhy
- Department of Molecular Biology, Umeå University, 901 87 Umeå, Sweden.
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50
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Pharmacologic Inhibition of Nedd8 Activation Enzyme Exposes CD4-Induced Epitopes within Env on Cells Expressing HIV-1. J Virol 2015; 90:2486-502. [PMID: 26676780 DOI: 10.1128/jvi.02736-15] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 12/09/2015] [Indexed: 01/17/2023] Open
Abstract
UNLABELLED HIV-1 Vpu decreases the exposure of epitopes within the viral envelope glycoprotein (Env) on the surface of infected cells by downregulating both BST2 and CD4. To test the hypothesis that inhibiting Vpu activity would increase the exposure of these epitopes and sensitize infected cells to antibody-dependent cellular cytotoxicity (ADCC), we treated cells with the Nedd8 activation enzyme (NAE) inhibitor MLN4924, which inhibits the cullin1-based ubiquitin ligase complex coopted by Vpu to degrade cellular targets. Treatment of HeLa cells with MLN4924 or expression of a dominant negative mutant of cullin1 inhibited the Vpu-mediated downregulation of CD4 but not the downregulation of BST2. NAE inhibition also increased the surface exposure of CD4-induced epitopes within Env on HEK293 cells containing an inducible HIV genome, on infected CEM T cells, and on infected primary T cells. In contrast, the Vpu-mediated downregulation of BST2 was substantially inhibited by MLN4924 only when T cells were treated with alpha interferon (IFN-α) to induce high levels of BST2 expression. As reported previously, the absence of vpu or nef and even more so the combined absence of these two genes sensitized infected cells to ADCC. However, NAE inhibition affected ADCC minimally. Paradoxically, even in infected, IFN-treated cells in which NAE inhibition substantially rescued the surface level of BST2, the surface level of Env detected with an antibody recognizing a CD4-independent epitope (2G12) was minimally increased. Mutation of the C-terminal Vpu residue W76, which supports the ability of Vpu to stimulate virion release by displacing BST2 from assembly sites on the plasma membrane by a cullin1-independent mechanism, increased the exposure of Env detected by 2G12 on infected T cells. Thus, inhibiting the displacement function of Vpu together with its ability to degrade CD4 and BST2 may be required to sensitize infected cells to ADCC. IMPORTANCE Pathogenic viruses encode gene products that enable evasion of host immune surveillance mechanisms. One such mechanism is antibody-dependent cellular cytotoxicity (ADCC), whereby host antibodies bind envelope glycoproteins of the virus that are inserted into the cellular membrane and direct the destruction of infected cells. Targeting pharmacologically the activity of HIV-1 Vpu, which contributes to evasion of ADCC, could potentially sensitize infected cells to this immune surveillance mechanism, an outcome that would have therapeutic implications with respect to the goal of curing HIV-1 infection. The Nedd8 activation enzyme inhibitor MLN4924 blocks the activity of the host ubiquitin ligase that Vpu coopts to direct the degradation of CD4 and BST2. We observed that while MLN4924 partially reverses the activity of Vpu and could become part of a therapeutic approach by virtue of CD4-induced epitope exposure, sufficient Vpu activity as an antagonist of BST2 persists despite this drug to allow escape from ADCC.
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