1
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Virgilio MC, Ramnani B, Chen T, Disbennett WM, Lubow J, Welch JD, Collins KL. HIV-1 Vpr combats the PU.1-driven antiviral response in primary human macrophages. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.03.21.533528. [PMID: 36993393 PMCID: PMC10055223 DOI: 10.1101/2023.03.21.533528] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
HIV-1 Vpr promotes efficient spread of HIV-1 from macrophages to T cells by transcriptionally downmodulating restriction factors that target HIV-1 Envelope protein (Env). Here we find that Vpr induces broad transcriptomic changes by targeting PU.1, a transcription factor necessary for expression of host innate immune response genes, including those that target Env. Consistent with this, we find silencing PU.1 in infected macrophages lacking Vpr rescues Env. Vpr downmodulates PU.1 through a proteasomal degradation pathway that depends on physical interactions with PU.1 and DCAF1, a component of the Cul4A E3 ubiquitin ligase. The capacity for Vpr to target PU.1 is highly conserved across primate lentiviruses. In addition to impacting infected cells, we find that Vpr suppresses expression of innate immune response genes in uninfected bystander cells, and that virion-associated Vpr can degrade PU.1. Together, we demonstrate Vpr counteracts PU.1 in macrophages to blunt antiviral immune responses and promote viral spread.
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2
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Mallorson R, Miyagi E, Kao S, Sukegawa S, Saito H, Fabryova H, Morellatto Ruggieri L, Mediouni S, Valente ST, Strebel K. Transcriptional regulation of the HIV-1 inhibitory factor human mannose receptor 1 by the myeloid-specific transcription factor PU.1. J Virol 2024; 98:e0170223. [PMID: 38078733 PMCID: PMC10804955 DOI: 10.1128/jvi.01702-23] [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: 11/01/2023] [Accepted: 11/17/2023] [Indexed: 01/04/2024] Open
Abstract
HIV-1 infection of human macrophages leads to the downmodulation of human mannose receptor 1 (hMRC1), a cell-surface glycoprotein that is involved in the host innate immune response. We previously reported that downmodulation of hMRC1 involves the transactivator of transcription (Tat)-dependent transcriptional silencing of the hMRC1 promoter. However, the inhibitory effect of Tat on hMRC1 transcription was indirect and involved inhibition of the transcriptional activator PU.1, which normally upregulates hMRC1 expression in macrophages and other myeloid cells. We cloned a 284-bp fragment of the hMRC1 promoter, and within it, we identified four PU.1 box elements. We assessed the relative contribution of each of the four PU.1 boxes to PU.1-dependent transcriptional regulation and, surprisingly, found that only one of the four PU.1 boxes [PU.1(b)] was critically required for PU.1-mediated upregulation of luciferase expression. Transfer of this PU.1 box to a heterologous promoter conferred PU.1 responsiveness to an otherwise PU.1 insensitive promoter. Electrophoretic mobility shift assays identified this PU.1 box as a direct binding site for PU.1 both in the context of the hMRC1 promoter and the heterologous promoter. Furthermore, mutational analysis of the PU.1 protein identified the C-terminal DNA-binding domain in PU.1 as the region responsible for interaction with the PU.1 box. Recombinant HIV-1 Tat protein did not bind to the hMRC1 promoter element but efficiently interfered with the binding of PU.1 protein to the hMRC1 promoter. Thus, Tat is likely to inhibit the formation of active PU.1 transcription complexes, presumably by binding to and depleting common transcriptional cofactors.IMPORTANCEHIV-1 infection of cells results in the modulation of cellular gene expression by virus-encoded proteins in a manner that benefits the virus. We reported that HIV-1 transactivator of transcription (Tat) dysregulates the expression of the human mannose receptor 1 (hMRC1). hMRC1 is involved in the innate immune response of macrophages to foreign pathogens. Tat does not act directly on the hMRC1 promoter but instead inhibits PU.1, a cellular transcription factor regulating hMRC1 gene expression. Here, we characterize the PU.1-dependent regulation of hMRC1 expression. We identified four potential PU.1 binding sites in the hMRC1 promoter region but found that only one, PU.1(b), functioned as a true binding site for PU.1. Transfer of the PU.1(b) box to a heterologous promoter did not activate this promoter per se but rendered it responsive to PU.1. Our results support the view that PU.1 acts as a transcriptional co-factor whose activity can be regulated by HIV-1 Tat.
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Affiliation(s)
- Rosa Mallorson
- Viral Biochemistry Section, Laboratory of Molecular Microbiology, NIAID, NIH, Bethesda, Maryland, USA
| | - Eri Miyagi
- Viral Biochemistry Section, Laboratory of Molecular Microbiology, NIAID, NIH, Bethesda, Maryland, USA
| | - Sandra Kao
- Viral Biochemistry Section, Laboratory of Molecular Microbiology, NIAID, NIH, Bethesda, Maryland, USA
| | - Sayaka Sukegawa
- Department of Molecular Virology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Hideki Saito
- Viral Biochemistry Section, Laboratory of Molecular Microbiology, NIAID, NIH, Bethesda, Maryland, USA
| | - Helena Fabryova
- Viral Biochemistry Section, Laboratory of Molecular Microbiology, NIAID, NIH, Bethesda, Maryland, USA
| | | | - Sonia Mediouni
- Department of Immunology and Microbiology, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation and Technology, Jupiter, Florida, USA
| | - Susana T. Valente
- Department of Immunology and Microbiology, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation and Technology, Jupiter, Florida, USA
| | - Klaus Strebel
- Viral Biochemistry Section, Laboratory of Molecular Microbiology, NIAID, NIH, Bethesda, Maryland, USA
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3
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Saito H, Sukegawa S, Kao S, Strebel K. Human Mannose Receptor 1 Attenuates HIV-1 Infectivity in a Virus Isolate-Specific Manner. Viruses 2023; 15:2057. [PMID: 37896833 PMCID: PMC10612104 DOI: 10.3390/v15102057] [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: 07/11/2023] [Revised: 10/03/2023] [Accepted: 10/04/2023] [Indexed: 10/29/2023] Open
Abstract
Human mannose receptor 1 (hMRC1) is a transmembrane glycoprotein that belongs to the C-type lectin family and is expressed on the surface of most tissue macrophages. hMRC1 contributes to the binding and transmission of HIV-1 and is involved in the endocytic uptake of HIV-1 for subsequent antigen presentation. We previously reported that hMRC1 functions as an antiviral factor by inhibiting virus release through a BST-2-like mechanism. The inhibition of virus release was not virus isolate-specific and, surprisingly, was not Env-dependent. We now report on another hMRC1 antiviral function that affects the infectivity of viral particles. Unlike its effect on virus release, the inhibition of viral infectivity by hMRC1 was virus isolate-specific. An analysis of chimeric Env revealed that the Env V3 region was a critical determinant for the inhibitory effect of hMRC1. Of note, exogenously expressed hMRC1 was packaged into viral particles in an Env-independent manner. Co-immunoprecipitation studies revealed a strong interaction of the hMRC1-sensitive NL43 Env with hMRC1, while the hMRC1-insensitive Envs of AD8 and 49.5 isolates interacted poorly if at all with hMRC1. An analysis of a panel of Transmitted/Founder (T/F) viruses revealed that all of them were R5-tropic, and more than half of them were inhibited by hMRC1. The detailed mechanism of how hMRC1 inhibits viral infectivity remains to be investigated. However, the high-affinity binding of hMRC1 to Env may cause a conformational change around the Env V3 region or obstruct the Env V3 region and may make it inaccessible for subsequent interaction with the coreceptor during virus entry.
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Affiliation(s)
| | | | | | - Klaus Strebel
- Viral Biochemistry Section, Laboratory of Molecular Microbiology, NIAID, NIH, Bethesda, MD 20892, USA; (H.S.); (S.S.); (S.K.)
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4
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The Myeloid-Specific Transcription Factor PU.1 Upregulates Mannose Receptor Expression but Represses Basal Activity of the HIV-LTR Promoter. J Virol 2022; 96:e0065222. [PMID: 35766490 PMCID: PMC9327697 DOI: 10.1128/jvi.00652-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Human mannose receptor 1 (MRC1) is a cell surface receptor expressed in macrophages and other myeloid cells that inhibits human immunodeficiency virus type 1 (HIV-1) particle release by tethering virions to producer cell membranes. HIV-1 counteracts MRC1 expression by inhibiting mrc1 transcription. Here, we investigated the mechanism of MRC1 downregulation in HIV-1-infected macrophages. We identified the myeloid cell-specific transcription factor PU.1 as critical for regulating MRC1 expression. In the course of our study, we recognized a complex interplay between HIV-1 Tat and PU.1 transcription factors: Tat upregulated HIV-1 gene expression but inhibited mrc1 transcription, whereas PU.1 inhibited HIV-1 transcription but activated MRC1 expression. Disturbing this equilibrium by silencing PU.1 resulted in increased HIV-1 gene expression and reduced MRC1 promoter activity. Our study identified PU.1 as a central player in transcriptional control, regulating a complex interplay between viral and host gene expression in HIV-infected macrophages. IMPORTANCE HIV-1 replication in primary human cells depends on the activity of virus-encoded proteins but also involves cellular factors that can either promote (viral dependency factors) or inhibit (host restriction factors) virus replication. In previous work, we identified human MRC1 as a macrophage-specific host restriction factor that inhibits the detachment of viral particles from infected cells. Here, we report that HIV-1 counteracts this effect of MRC1 by imposing a transcriptional block on cellular MRC1 gene expression. The transcriptional inhibition of the MRC1 gene is accomplished by Tat, an HIV-1 factor whose best-described function actually is the enhancement of HIV-1 gene expression. Thus, HIV-1 has evolved to use the same protein for (i) activation of its own gene expression while (ii) inhibiting expression of MRC1 and other host factors.
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5
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Mori L, Valente ST. Cure and Long-Term Remission Strategies. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2022; 2407:391-428. [PMID: 34985678 DOI: 10.1007/978-1-0716-1871-4_26] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The majority of virally suppressed individuals will experience rapid viral rebound upon antiretroviral therapy (ART) interruption, providing a strong rationale for the development of cure strategies. Moreover, despite ART virological control, HIV infection is still associated with chronic immune activation, inflammation, comorbidities, and accelerated aging. These effects are believed to be due, in part, to low-grade persistent transcription and trickling production of viral proteins from the pool of latent proviruses constituting the viral reservoir. In recent years there has been an increasing interest in developing what has been termed a functional cure for HIV. This approach entails the long-term, durable control of viral expression in the absence of therapy, preventing disease progression and transmission, despite the presence of detectable integrated proviruses. One such strategy, the block-and-lock approach for a functional cure, proposes the epigenetic silencing of proviral expression, locking the virus in a profound latent state, from which reactivation is very unlikely. The proof-of-concept for this approach was demonstrated with the use of a specific small molecule targeting HIV transcription. Here we review the principles behind the block-and-lock approach and some of the additional strategies proposed to silence HIV expression.
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Affiliation(s)
- Luisa Mori
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, FL, USA
| | - Susana T Valente
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, FL, USA.
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6
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Torkzaban B, Natarajaseenivasan K, Mohseni Ahooyi T, Shekarabi M, Amini S, Langford TD, Khalili K. The lncRNA LOC102549805 (U1) modulates neurotoxicity of HIV-1 Tat protein. Cell Death Dis 2020; 11:835. [PMID: 33033233 PMCID: PMC7546609 DOI: 10.1038/s41419-020-03033-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 07/16/2020] [Accepted: 07/17/2020] [Indexed: 02/06/2023]
Abstract
HIV-1 Tat is a potent neurotoxic protein that is released by HIV-1 infected cells in the brain and perturbs neuronal homeostasis, causing a broad range of neurological disorders in people living with HIV-1. Furthermore, the effects of Tat have been addressed in numerous studies to investigate the molecular events associated with neuronal cells survival and death. Here, we discovered that exposure of rat primary neurons to Tat resulted in the up-regulation of an uncharacterized long non-coding RNA (lncRNA), LOC102549805 (lncRNA-U1). Our observations showed that increased expression of lncRNA-U1 in neurons disrupts bioenergetic pathways by dysregulating homeostasis of Ca2+, mitigating mitochondrial oxygen reduction, and decreasing ATP production, all of which point mitochondrial impairment in neurons via the Tat-mediated lncRNA-U1 induction. These changes were associated with imbalances in autophagy and apoptosis pathways. Additionally, this study showed the ability of Tat to modulate expression of the neuropeptide B/W receptor 1 (NPBWR1) gene via up-regulation of lncRNA-U1. Collectively, our results identified Tat-mediated lncRNA-U1 upregulation resulting in disruption of neuronal homeostasis.
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Affiliation(s)
- Bahareh Torkzaban
- Department of Neuroscience, Center for Neurovirology, Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA, 19140, USA
| | - Kalimuthusamy Natarajaseenivasan
- Department of Neuroscience, Center for Neurovirology, Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA, 19140, USA
| | - Taha Mohseni Ahooyi
- Department of Neuroscience, Center for Neurovirology, Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA, 19140, USA
| | - Masoud Shekarabi
- Department of Neuroscience, Center for Neurovirology, Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA, 19140, USA
| | - Shohreh Amini
- Department of Neuroscience, Center for Neurovirology, Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA, 19140, USA
| | - T Dianne Langford
- Department of Neuroscience, Center for Neurovirology, Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA, 19140, USA
| | - Kamel Khalili
- Department of Neuroscience, Center for Neurovirology, Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA, 19140, USA.
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7
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Lubow J, Virgilio MC, Merlino M, Collins DR, Mashiba M, Peterson BG, Lukic Z, Painter MM, Gomez-Rivera F, Terry V, Zimmerman G, Collins KL. Mannose receptor is an HIV restriction factor counteracted by Vpr in macrophages. eLife 2020; 9:e51035. [PMID: 32119644 PMCID: PMC7051176 DOI: 10.7554/elife.51035] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 01/25/2020] [Indexed: 12/21/2022] Open
Abstract
HIV-1 Vpr is necessary for maximal HIV infection and spread in macrophages. Evolutionary conservation of Vpr suggests an important yet poorly understood role for macrophages in HIV pathogenesis. Vpr counteracts a previously unknown macrophage-specific restriction factor that targets and reduces the expression of HIV Env. Here, we report that the macrophage mannose receptor (MR), is a restriction factor targeting Env in primary human monocyte-derived macrophages. Vpr acts synergistically with HIV Nef to target distinct stages of the MR biosynthetic pathway and dramatically reduce MR expression. Silencing MR or deleting mannose residues on Env rescues Env expression in HIV-1-infected macrophages lacking Vpr. However, we also show that disrupting interactions between Env and MR reduces initial infection of macrophages by cell-free virus. Together these results reveal a Vpr-Nef-Env axis that hijacks a host mannose-MR response system to facilitate infection while evading MR's normal role, which is to trap and destroy mannose-expressing pathogens.
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Affiliation(s)
- Jay Lubow
- Department of Microbiology and Immunology, University of MichiganAnn ArborUnited States
| | - Maria C Virgilio
- Cellular and Molecular Biology Program, University of MichiganAnn ArborUnited States
| | - Madeline Merlino
- Department of Internal Medicine, University of MichiganAnn ArborUnited States
| | - David R Collins
- Department of Microbiology and Immunology, University of MichiganAnn ArborUnited States
| | - Michael Mashiba
- Graduate Program in Immunology, University of MichiganAnn ArborUnited States
| | - Brian G Peterson
- Department of Biological ChemistryUniversity of MichiganAnn ArborUnited States
| | - Zana Lukic
- Department of Internal Medicine, University of MichiganAnn ArborUnited States
| | - Mark M Painter
- Graduate Program in Immunology, University of MichiganAnn ArborUnited States
| | | | - Valeri Terry
- Department of Internal Medicine, University of MichiganAnn ArborUnited States
| | - Gretchen Zimmerman
- Graduate Program in Immunology, University of MichiganAnn ArborUnited States
| | - Kathleen L Collins
- Cellular and Molecular Biology Program, University of MichiganAnn ArborUnited States
- Department of Internal Medicine, University of MichiganAnn ArborUnited States
- Graduate Program in Immunology, University of MichiganAnn ArborUnited States
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8
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Vpr and Its Cellular Interaction Partners: R We There Yet? Cells 2019; 8:cells8111310. [PMID: 31652959 PMCID: PMC6912716 DOI: 10.3390/cells8111310] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 10/22/2019] [Accepted: 10/23/2019] [Indexed: 12/17/2022] Open
Abstract
Vpr is a lentiviral accessory protein that is expressed late during the infection cycle and is packaged in significant quantities into virus particles through a specific interaction with the P6 domain of the viral Gag precursor. Characterization of the physiologically relevant function(s) of Vpr has been hampered by the fact that in many cell lines, deletion of Vpr does not significantly affect viral fitness. However, Vpr is critical for virus replication in primary macrophages and for viral pathogenesis in vivo. It is generally accepted that Vpr does not have a specific enzymatic activity but functions as a molecular adapter to modulate viral or cellular processes for the benefit of the virus. Indeed, many Vpr interacting factors have been described by now, and the goal of this review is to summarize our current knowledge of cellular proteins targeted by Vpr.
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9
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Sukegawa S, Miyagi E, Bouamr F, Farkašová H, Strebel K. Mannose Receptor 1 Restricts HIV Particle Release from Infected Macrophages. Cell Rep 2019; 22:786-795. [PMID: 29346774 PMCID: PMC5792083 DOI: 10.1016/j.celrep.2017.12.085] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 11/21/2017] [Accepted: 12/22/2017] [Indexed: 01/18/2023] Open
Abstract
Human mannose receptor 1 (hMRC1) is expressed on the surface of most tissue macrophages, dendritic cells, and select lymphatic or liver endothelial cells. HMRC1 contributes to the binding of HIV-1 to monocyte-derived macrophages (MDMs) and is involved in the endocytic uptake of HIV-1 into these cells. Here, we identify hMRC1 as an antiviral factor that inhibits virus release through a bone marrow stromal antigen 2 (BST-2)-like mechanism. Virions produced in the presence of hMRC1 accumulated in clusters at the cell surface but were fully infectious. HIV-1 counteracted the effect by transcriptional silencing of hMRC1. The effect of hMRC1 was not virus isolate specific. Surprisingly, deletion of the Env protein, which is known to interact with hMRC1, did not relieve the hMRC1 antiviral activity, suggesting the involvement of additional cellular factor(s) in the process. Our data reveal an antiviral mechanism that is active in primary human macrophages and is counteracted by HIV-1 through downregulation of hMRC1.
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Affiliation(s)
- Sayaka Sukegawa
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, NIH, Building 4, Room 312, 4 Center Drive, MSC 0460, Bethesda, MD 20892, USA
| | - Eri Miyagi
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, NIH, Building 4, Room 312, 4 Center Drive, MSC 0460, Bethesda, MD 20892, USA
| | - Fadila Bouamr
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, NIH, Building 4, Room 312, 4 Center Drive, MSC 0460, Bethesda, MD 20892, USA
| | - Helena Farkašová
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, NIH, Building 4, Room 312, 4 Center Drive, MSC 0460, Bethesda, MD 20892, USA
| | - Klaus Strebel
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, NIH, Building 4, Room 312, 4 Center Drive, MSC 0460, Bethesda, MD 20892, USA.
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10
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Epigenetic alterations are associated with monocyte immune dysfunctions in HIV-1 infection. Sci Rep 2018; 8:5505. [PMID: 29615725 PMCID: PMC5882962 DOI: 10.1038/s41598-018-23841-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 03/20/2018] [Indexed: 01/28/2023] Open
Abstract
Monocytes are key cells in the immune dysregulation observed during human immunodeficiency virus (HIV) infection. The events that take place specifically in monocytes may contribute to the systemic immune dysfunction characterized by excessive immune activation in infected individuals, which directly correlates with pathogenesis and progression of the disease. Here, we investigated the immune dysfunction in monocytes from untreated and treated HIV + patients and associated these findings with epigenetic changes. Monocytes from HIV patients showed dysfunctional ability of phagocytosis and killing, and exhibited dysregulated cytokines and reactive oxygen species production after M. tuberculosis challenge in vitro. In addition, we showed that the expression of enzymes responsible for epigenetic changes was altered during HIV infection and was more prominent in patients that had high levels of soluble CD163 (sCD163), a newly identified plasmatic HIV progression biomarker. Among the enzymes, histone acetyltransferase 1 (HAT1) was the best epigenetic biomarker correlated with HIV - sCD163 high patients. In conclusion, we confirmed that HIV impairs effector functions of monocytes and these alterations are associated with epigenetic changes that once identified could be used as targets in therapies aiming the reduction of the systemic activation state found in HIV patients.
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11
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Clark E, Nava B, Caputi M. Tat is a multifunctional viral protein that modulates cellular gene expression and functions. Oncotarget 2018; 8:27569-27581. [PMID: 28187438 PMCID: PMC5432358 DOI: 10.18632/oncotarget.15174] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 01/24/2017] [Indexed: 12/02/2022] Open
Abstract
The human immunodeficiency virus type I (HIV-1) has developed several strategies to condition the host environment to promote viral replication and spread. Viral proteins have evolved to perform multiple functions, aiding in the replication of the viral genome and modulating the cellular response to the infection. Tat is a small, versatile, viral protein that controls transcription of the HIV genome, regulates cellular gene expression and generates a permissive environment for viral replication by altering the immune response and facilitating viral spread to multiple tissues. Studies carried out utilizing biochemical, cellular, and genomic approaches show that the expression and activity of hundreds of genes and multiple molecular networks are modulated by Tat via multiple mechanisms.
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Affiliation(s)
- Evan Clark
- Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL, USA
| | - Brenda Nava
- Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL, USA
| | - Massimo Caputi
- Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL, USA
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12
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Curtale G, Renzi TA, Drufuca L, Rubino M, Locati M. Glucocorticoids downregulate TLR4 signaling activity via its direct targeting by miR-511-5p. Eur J Immunol 2017; 47:2080-2089. [PMID: 28776644 DOI: 10.1002/eji.201747044] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Revised: 06/28/2017] [Accepted: 07/31/2017] [Indexed: 11/05/2022]
Abstract
Endotoxin tolerance assures proper regulation of the TLR4 signaling pathway and avoids uncontrolled inflammation, limiting tissue damage and endotoxin shock development. Though underlying molecular mechanisms are still undefined, evidence indicates the involvement of microRNAs, which represent a new layer of regulation of inflammatory pathways. Here, we report that LPS and other inflammatory stimuli repress miR-511-5p expression in human monocytes, while anti-inflammatory stimuli, such as TGF-β and glucocorticoids, have the opposite effect. MiR-511-5p levels selectively influenced cell activation when endotoxin was used, while biological activity of other TLR agonists was unaffected. Consistent with this, TLR4 was validated as the miR-511-5p direct target responsible for glucocorticoids- and TGF-β-mediated inhibition of pro-inflammatory cytokines production observed in endotoxin tolerant monocytes. MiR-511-5p thus acts as an intracellular mediator of glucocorticoids and TGF-β for the induction of endotoxin tolerance in human monocytes.
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Affiliation(s)
- Graziella Curtale
- Department of Medical Biotechnologies and Translational Medicine, University of Milan, Milan, Italy.,Humanitas Clinical and Research Center, Rozzano, Italy
| | - Tiziana A Renzi
- Department of Medical Biotechnologies and Translational Medicine, University of Milan, Milan, Italy.,Humanitas Clinical and Research Center, Rozzano, Italy
| | - Lorenzo Drufuca
- Department of Medical Biotechnologies and Translational Medicine, University of Milan, Milan, Italy.,Humanitas Clinical and Research Center, Rozzano, Italy
| | | | - Massimo Locati
- Department of Medical Biotechnologies and Translational Medicine, University of Milan, Milan, Italy.,Humanitas Clinical and Research Center, Rozzano, Italy
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13
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Abstract
Despite the success of cART, greater than 50% of HIV infected people develop cognitive and motor deficits termed HIV-associated neurocognitive disorders (HAND). Macrophages are the major cell type infected in the CNS. Unlike for T cells, the virus does not kill macrophages and these long-lived cells may become HIV reservoirs in the brain. They produce cytokines/chemokines and viral proteins that promote inflammation and neuronal damage, playing a key role in HIV neuropathogenesis. HIV Tat is the transactivator of transcription that is essential for replication and transcriptional regulation of the virus and is the first protein to be produced after HIV infection. Even with successful cART, Tat is produced by infected cells. In this study we examined the role of the HIV Tat protein in the regulation of gene expression in human macrophages. Using THP-1 cells, a human monocyte/macrophage cell line, and their infection with lentivirus, we generated stable cell lines that express Tat-Flag. We performed ChIP-seq analysis of these cells and found 66 association sites of Tat in promoter or coding regions. Among these are C5, CRLF2/TSLPR, BDNF, and APBA1/Mint1, genes associated with inflammation/damage. We confirmed the association of Tat with these sequences by ChIP assay and expression of these genes in our THP-1 cell lines by qRT-PCR. We found that HIV Tat increased expression of C5, APBA1, and BDNF, and decreased CRLF2. The K50A Tat-mutation dysregulated expression of these genes without affecting the binding of the Tat complex to their gene sequences. Our data suggest that HIV Tat, produced by macrophage HIV reservoirs in the brain despite successful cART, contributes to neuropathogenesis in HIV-infected people.
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14
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Sandstrom TS, Ranganath N, Angel JB. Impairment of the type I interferon response by HIV-1: Potential targets for HIV eradication. Cytokine Growth Factor Rev 2017; 37:1-16. [PMID: 28455216 DOI: 10.1016/j.cytogfr.2017.04.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 04/20/2017] [Accepted: 04/21/2017] [Indexed: 12/11/2022]
Abstract
By interfering with the type I interferon (IFN1) response, human immunodeficiency virus 1 (HIV-1) can circumvent host antiviral signalling and establish persistent viral reservoirs. HIV-1-mediated defects in the IFN pathway are numerous, and include the impairment of protein receptors involved in pathogen detection, downstream signalling cascades required for IFN1 upregulation, and expression or function of key IFN1-inducible, antiviral proteins. Despite this, the activation of IFN1-inducible, antiviral proteins has been shown to facilitate the killing of latently HIV-infected cells in vitro. Understanding how IFN1 signalling is blocked in physiologically-relevant models of HIV-1 infection, and whether these defects can be reversed, is therefore of great importance for the development of novel therapeutic strategies aimed at eradicating the HIV-1 reservoir.
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Affiliation(s)
- Teslin S Sandstrom
- Ottawa Hospital Research Institute, ORCC Room C4445, 501 Smyth Road, Ottawa, ON, K1H 8L6, Canada; Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, ON, K1H 8M5, Canada.
| | - Nischal Ranganath
- Ottawa Hospital Research Institute, ORCC Room C4445, 501 Smyth Road, Ottawa, ON, K1H 8L6, Canada; Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, ON, K1H 8M5, Canada.
| | - Jonathan B Angel
- Ottawa Hospital Research Institute, ORCC Room C4445, 501 Smyth Road, Ottawa, ON, K1H 8L6, Canada; Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, ON, K1H 8M5, Canada; Division of Infectious Diseases, Ottawa Hospital-General Campus, 501 Smyth Road, Ottawa, ON, K1H 8L6, Canada.
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15
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Exosome-associated release, uptake, and neurotoxicity of HIV-1 Tat protein. J Neurovirol 2016; 22:774-788. [PMID: 27173397 DOI: 10.1007/s13365-016-0451-6] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 04/18/2016] [Accepted: 05/02/2016] [Indexed: 12/17/2022]
Abstract
HIV-1 Tat is an indispensible transactivator for HIV gene transcription and replication. It has been shown to exit cells as a free protein and enter neighboring cells or interact with surface receptors of neighboring cells to regulate gene expression and cell function. In this study, we report, for the first time, exosome-associated Tat release and uptake. Using a HIV-1 LTR-driven luciferase reporter-based cell assay and Western blotting or in combination with exosome inhibitor, OptiPrep gradient fractionation, and exosome depletion, we demonstrated significant presence of HIV-1 Tat in exosomes derived from Tat-expressing primary astrocytes, Tat-transfected U373.MG and 293T, and HIV-infected MT4. We further showed that exosome-associated Tat from Tat-expressing astrocytes was capable of causing neurite shortening and neuron death, further supporting that this new form of extracellular Tat is biologically active. Lastly, we constructed a Tat mutant deleted of its basic domain and determined the role of the basic domain in Tat trafficking into exosomes. Basic domain-deleted Tat exhibited no apparent effects on Tat trafficking into exosomes, while maintained its dominant-negative function in Tat-mediated LTR transactivation. Taken together, these results show a significant fraction of Tat is secreted and present in the form of exosomes and may contribute to the stability of extracellular Tat and broaden the spectrum of its target cells.
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16
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Wei J, Zhang Y, Knapp PE, Zhao T. HIV-1 Tat regulates the expression of the dcw operon and stimulates the proliferation of bacteria. Microb Pathog 2015; 90:34-40. [PMID: 26596708 DOI: 10.1016/j.micpath.2015.11.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Revised: 09/04/2015] [Accepted: 11/12/2015] [Indexed: 11/24/2022]
Abstract
Infections of pathogenic bacteria are very common in acquired immunodeficiency syndrome (AIDS) patients. However, the biological effects of HIV-1 Tat on bacteria are incompletely understood. In this study, HIV-1 Tat was expressed in Escherichia coli and Pseudomonas aeruginosa (PA01) to investigate its biological effects on bacteria. Bacterial cells expressing either HIV-1 Tat1-86 (Tat1-86) or HIV-1 Tat1-72 (Tat1-72) grow significantly faster than those with either only an empty vector or an unrelated control (GFP or Rluc). Supplementation of purified HIV-1 Tat1-86 or Tat1-101 protein into bacterial culture medium stimulated the growth of both E. coli and PA01. The expression profile of certain cell division-associated genes, such as those in the division cell wall (dcw) operon (ftsA, ftsQ, ftsW and ftsZ), yafO and zipA, was altered in HIV-1 Tat1-86 expressing E. coli BL21(DE3). Furthermore, the expression of firefly luciferase (Fluc) reporter gene, when engineered for control by the dcw promoter and terminator, was enhanced by HIV-1 Tat in E. coli, confirming that HIV-1 Tat transcriptionally regulates the expression of the dcw operon. The finding that HIV-1 Tat stimulates bacterial growth whether it is produced intracellularly or applied extracellularly may have relevance for HIV patients who are highly susceptible to opportunistic bacterial infections. Contents category: Viruses -Retroviruses. The GenBank accession number for the sequence of HIV-1 Tat1-86 is AF324439.1.
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Affiliation(s)
- Jinsong Wei
- Department of Biochemistry and Molecular Biology, College of Life Sciences, Northwest Agriculture and Forestry University, Yangling, Shaanxi 712100, China
| | - Yumin Zhang
- Department of Biochemistry and Molecular Biology, College of Life Sciences, Northwest Agriculture and Forestry University, Yangling, Shaanxi 712100, China
| | - Pamela E Knapp
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Tianyong Zhao
- Department of Biochemistry and Molecular Biology, College of Life Sciences, Northwest Agriculture and Forestry University, Yangling, Shaanxi 712100, China.
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17
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Reeder JE, Kwak YT, McNamara RP, Forst CV, D'Orso I. HIV Tat controls RNA Polymerase II and the epigenetic landscape to transcriptionally reprogram target immune cells. eLife 2015; 4. [PMID: 26488441 PMCID: PMC4733046 DOI: 10.7554/elife.08955] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 10/20/2015] [Indexed: 12/22/2022] Open
Abstract
HIV encodes Tat, a small protein that facilitates viral transcription by binding an RNA structure (trans-activating RNA [TAR]) formed on nascent viral pre-messenger RNAs. Besides this well-characterized mechanism, Tat appears to modulate cellular transcription, but the target genes and molecular mechanisms remain poorly understood. We report here that Tat uses unexpected regulatory mechanisms to reprogram target immune cells to promote viral replication and rewire pathways beneficial for the virus. Tat functions through master transcriptional regulators bound at promoters and enhancers, rather than through cellular ‘TAR-like’ motifs, to both activate and repress gene sets sharing common functional annotations. Despite the complexity of transcriptional regulatory mechanisms in the cell, Tat precisely controls RNA polymerase II recruitment and pause release to fine-tune the initiation and elongation steps in target genes. We propose that a virus with a limited coding capacity has optimized its genome by evolving a small but ‘multitasking’ protein to simultaneously control viral and cellular transcription. DOI:http://dx.doi.org/10.7554/eLife.08955.001 The human immunodeficiency virus (HIV) reproduces and spreads throughout the body by hijacking human immune cells and causing them to copy the virus’s genetic information. As the virus multiplies, it also causes the death of the immune system cells that help the human body recognize and eliminate viruses. This allows the virus to multiply unchecked. Studies of the genetic material of HIV – which is in the form of single-stranded RNA molecules and contains only a handful of genes – have begun to reveal how the virus can wreak such havoc to the human immune system. A small protein encoded by the virus, called Tat, boosts the expression of HIV genes in infected immune cells by binding to a structure that forms on newly synthesized viral RNAs. Recent evidence suggests that HIV also changes the expression of human genes to make immune cells more hospitable to the virus. However, it was not known exactly which specific genes are targeted, or how the virus alters their expression. Now, Reeder, Kwak et al. reveal how the Tat protein alters the expression of more than 400 human genes. Rather than bind to the same structure seen in newly forming HIV RNAs, Tat turns on or off the expression of its human target genes by interacting with proteins that regulate human gene expression. In doing so, Tat is able to precisely control the activity of an enzyme called RNA Polymerase II that is necessary for the early steps of gene expression. Tat’s multitasking ability – boosting HIV gene expression at the same time as reprogramming human gene expression – helps explain how a virus with so little genetic material of its own can perform such a wide range of activities in infected cells. The work of Reeder, Kwak et al. suggests that Tat reshapes the human genome to position target genes in ways that allow them to be efficiently turned on or off. Future studies will further reveal how Tat accomplishes this genome remodeling during different stages of infection. In addition, further research is also necessary to look closely into the sets of genes targeted by Tat to find patterns of genes that work together to alter cell behavior, and investigate how these new behaviors allow HIV to thrive. DOI:http://dx.doi.org/10.7554/eLife.08955.002
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Affiliation(s)
- Jonathan E Reeder
- Department of Biological Sciences, University of Texas at Dallas, Richardson, United States.,Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Youn-Tae Kwak
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Ryan P McNamara
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Christian V Forst
- Department of Genetics and Genomic Sciences, Institute for Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, United States
| | - Iván D'Orso
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, United States
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18
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HIV-1 Tat inhibits phagocytosis by preventing the recruitment of Cdc42 to the phagocytic cup. Nat Commun 2015; 6:6211. [PMID: 25648615 DOI: 10.1038/ncomms7211] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 01/06/2015] [Indexed: 11/08/2022] Open
Abstract
Most macrophages remain uninfected in HIV-1-infected patients. Nevertheless, the phagocytic capacity of phagocytes from these patients is impaired, favouring the multiplication of opportunistic pathogens. The basis for this phagocytic defect is not known. HIV-1 Tat protein is efficiently secreted by infected cells. Secreted Tat can enter uninfected cells and reach their cytosol. Here we found that extracellular Tat, at the subnanomolar concentration present in the sera of HIV-1-infected patients, inhibits the phagocytosis of Mycobacterium avium or opsonized Toxoplasma gondii by human primary macrophages. This inhibition results from a defect in mannose- and Fcγ-receptor-mediated phagocytosis, respectively. Inhibition relies on the interaction of Tat with phosphatidylinositol (4,5)bisphosphate that interferes with the recruitment of Cdc42 to the phagocytic cup, thereby preventing Cdc42 activation and pseudopod elongation. Tat also inhibits FcγR-mediated phagocytosis in neutrophils and monocytes. This study provides a molecular basis for the phagocytic defects observed in uninfected phagocytes following HIV-1 infection.
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19
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Dhamija N, Choudhary D, Ladha JS, Pillai B, Mitra D. Tat predominantly associates with host promoter elements in HIV-1-infected T-cells - regulatory basis of transcriptional repression of c-Rel. FEBS J 2014; 282:595-610. [PMID: 25472883 DOI: 10.1111/febs.13168] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 11/19/2014] [Accepted: 12/02/2014] [Indexed: 11/28/2022]
Abstract
HIV-1 Tat is a multifunctional regulatory protein that, in addition to its primary function of transactivating viral transcription, also tends to modulate cellular gene expression, for which the molecular mechanism remains to be clarified. We have reported earlier nuclear factor kappa B (NFκB) enhancer binding activity of Tat and proposed this DNA binding activity as a possible molecular basis for Tat-mediated regulation of cellular gene expression in infected cells. In the present study, we analyzed the genome-wide occupancy of Tat protein on host cell chromatin in HIV-1-infected T-cells to investigate a potential role of Tat on cellular gene expression. The results obtained identify a spectrum of binding sites of Tat protein on the chromatin and reveal that Tat is also recruited on a number of cellular gene promoters in HIV-1-infected T-cells, indicating its possible involvement in the regulation of gene expression of such cellular genes. Tat was identified as a repressor of one such validated gene, c-Rel, because it downregulates the expression of c-Rel in both Tat expressing and HIV-1-infected T-cells. The results also show that Tat downregulates c-Rel promoter activity by interacting with specific NFκB sites on the c-Rel promoter, thus providing a molecular basis of Tat-mediated regulation of cellular gene expression. Thus, in the present study, we have not only identified recruitment sites of Tat on the chromatin in HIV-1-infected T-cells, but also report for the first time that c-Rel is downregulated in HIV-1-infected cells specifically by interaction of Tat with NFκB binding sites on the promoter.
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20
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Expression of the mannose receptor CD206 in HIV and SIV encephalitis: a phenotypic switch of brain perivascular macrophages with virus infection. J Neuroimmune Pharmacol 2014; 9:716-26. [PMID: 25146376 DOI: 10.1007/s11481-014-9564-y] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Accepted: 08/17/2014] [Indexed: 12/15/2022]
Abstract
We examined the expression of the mannose receptor CD206 by perivascular macrophages (PVM) in normal human and monkey brains and in brains of HIV-infected humans and of monkeys infected with simian immunodeficiency virus (SIV). Depletion of brain PVM in SIV-infected monkeys by intrathecal injection of liposome-encapsulated bisphosphonates eliminated CD206-expressing cells in the brain, confirming their perivascular location and phagocytic capacity. In vivo labeling with bromodeoxyuridine in normal uninfected and SIV-infected macaques in combination with CD206 immunostaining revealed a CD206+-to-CD206- shift within pre-existing PVM during SIV brain infection and neuroinflammation. These findings identify CD206 as a unique marker of human and macaque PVM, and underscore the utility of this marker in studying the origin, turnover and functions of these cells in AIDS.
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21
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Marban C, Su T, Ferrari R, Li B, Vatakis D, Pellegrini M, Zack JA, Rohr O, Kurdistani SK. Genome-wide binding map of the HIV-1 Tat protein to the human genome. PLoS One 2011; 6:e26894. [PMID: 22073215 PMCID: PMC3208564 DOI: 10.1371/journal.pone.0026894] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Accepted: 09/22/2011] [Indexed: 01/14/2023] Open
Abstract
The HIV-1 Trans-Activator of Transcription (Tat) protein binds to multiple host cellular factors and greatly enhances the level of transcription of the HIV genome. While Tat's control of viral transcription is well-studied, much less is known about the interaction of Tat with the human genome. Here, we report the genome-wide binding map of Tat to the human genome in Jurkat T cells using chromatin immunoprecipitation combined with next-generation sequencing. Surprisingly, we found that ~53% of the Tat target regions are within DNA repeat elements, greater than half of which are Alu sequences. The remaining target regions are located in introns and distal intergenic regions; only ~7% of Tat-bound regions are near transcription start sites (TSS) at gene promoters. Interestingly, Tat binds to promoters of genes that, in Jurkat cells, are bound by the ETS1 transcription factor, the CBP histone acetyltransferase and/or are enriched for histone H3 lysine 4 tri-methylation (H3K4me3) and H3K27me3. Tat binding is associated with genes enriched with functions in T cell biology and immune response. Our data reveal that Tat's interaction with the host genome is more extensive than previously thought, with potentially important implications for the viral life cycle.
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Affiliation(s)
- Céline Marban
- Institut de Virologie, Université de Strasbourg, Strasbourg, France
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Trent Su
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- Division of Oral Biology and Medicine, School of Dentistry, University of California Los Angeles, Los Angeles, California, United States of America
| | - Roberto Ferrari
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Bing Li
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Dimitrios Vatakis
- Division of Hematology and Oncology, Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Matteo Pellegrini
- Department of Molecular, Cellular, and Developmental Biology, University of California Los Angeles, Los Angeles, California, United States of America
- Eli and Edythe Broad Centre of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, California, United States of America
| | - Jerome A. Zack
- Division of Hematology and Oncology, Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- Eli and Edythe Broad Centre of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, California, United States of America
| | - Olivier Rohr
- Institut de Virologie, Université de Strasbourg, Strasbourg, France
- Institut Universitaire de France (IUF), Paris, France
- * E-mail: (SKK); (OR)
| | - Siavash K. Kurdistani
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- Eli and Edythe Broad Centre of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, California, United States of America
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail: (SKK); (OR)
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22
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Kalantari P, Harandi OF, Hankey PA, Henderson AJ. HIV-1 Tat mediates degradation of RON receptor tyrosine kinase, a regulator of inflammation. THE JOURNAL OF IMMUNOLOGY 2008; 181:1548-55. [PMID: 18606710 DOI: 10.4049/jimmunol.181.2.1548] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
HIV encodes several proteins, including Tat, that have been demonstrated to modulate the expression of receptors critical for innate immunity, including MHC class I, mannose receptor, and beta(2)-microglobulin. We demonstrate that Tat targets the receptor tyrosine kinase recepteur d'origine nantais (RON), which negatively regulates inflammation and HIV transcription, for proteosome degradation. Tat decreases cell surface RON expression in HIV-infected monocytic cells, and Tat-mediated degradation of RON protein is blocked by inhibitors of proteosome activity. Tat specifically induced down-regulation of RON and not other cell surface receptors, such as the transferrin receptor, the receptor tyrosine kinase TrkA, or monocytic markers CD14 and ICAM-1. The Tat trans activation domain is required for RON degradation, and this down-regulation is dependent on the integrity of the kinase domain of RON receptor. We propose that Tat mediates degradation of RON through a ubiquitin-proteosome pathway, and suggest that by targeting signals that modulate inflammation, Tat creates a microenvironment that is optimal for HIV replication and progression of AIDS-associated diseases.
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Affiliation(s)
- Parisa Kalantari
- Graduate Program in Pathobiology, Center for Molecular Immunology and Infectious Diseases, Pennsylvania State University, PA 16802, USA
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23
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Yin ZJ, Li Q, Meng XB, Li ZJ. Design and synthesis of novel multivalent mannosides targeting the mannose receptor. Carbohydr Res 2007; 342:2729-34. [PMID: 17880930 DOI: 10.1016/j.carres.2007.08.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2007] [Revised: 08/16/2007] [Accepted: 08/21/2007] [Indexed: 11/22/2022]
Abstract
According to the characteristics of C-type lectin-like domains in the mannose receptor (MR), a novel design of multivalent mannosides targeting the MR was accomplished. Beginning with a divalent mannoside as the sugar unit, a series of multivalent mannosides with variations in both valence and space were synthesized in a convergent approach. The synthetic multivalent mannosides are to be explored to study MR-sugar binding events.
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Affiliation(s)
- Zhao-Jun Yin
- Department of Chemical Biology, School of Pharmaceutical Sciences, State Key Laboratory of Natural and Biomimetic Drugs, Peking University Health Science Center, Beijing 100083, PR China
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24
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Quaranta MG, Mattioli B, Giordani L, Viora M. The immunoregulatory effects of HIV‐1 Nef on dendritic cells and the pathogenesis of AIDS. FASEB J 2006; 20:2198-208. [PMID: 17077296 DOI: 10.1096/fj.06-6260rev] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Dendritic cells (DC) play a crucial role in the generation and regulation of immunity, and their interaction with HIV is relevant in the pathogenesis of AIDS favoring both the initial establishment and spread of the infection and the development of antiviral immunity. HIV-1 Nef is an essential factor for efficient viral replication and pathogenesis, and several studies have been addressed to assess the possible influence of endogenous or exogenous Nef on DC biology. Our findings and other reported data described in this review demonstrate that Nef subverts DC biology interfering with phenotypical, morphological, and functional DC developmental programs, thus representing a viral tool underlying AIDS pathogenesis. This review provides an overview on the mechanism by which Nef, hijacking DC functional activity, may favor both the replication of HIV-1 and the escape from immune surveillance. Overall, the findings described here may contribute to the understanding of Nef function, mechanism of action, and cellular partners. Further elucidation of genes induced through Nef signaling in DC could reveal pathways used by DC to drive HIV spread and will be critical to identify therapeutic strategies to bias the DC system toward activation of antiviral immunity instead of facilitating virus dissemination.
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Affiliation(s)
- Maria Giovanna Quaranta
- Department of Drug Research and Evaluation, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
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25
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Caldwell RL, Lane KB, Shepherd VL. HIV-1 Tat interaction with cyclin T1 represses mannose receptor and the bone morphogenetic protein receptor-2 transcription. Arch Biochem Biophys 2006; 449:27-33. [PMID: 16615932 DOI: 10.1016/j.abb.2006.02.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2005] [Revised: 02/24/2006] [Accepted: 02/24/2006] [Indexed: 11/23/2022]
Abstract
Macrophage transcription is significantly altered by HIV-1 infection. HIV Tat, an immediate-early product of the viral lifecycle, interacts with host transcription factors to alter host gene expression. We have previously shown that Tat represses transcription from the mannose receptor (MR) and the bone morphogenetic protein receptor-2 (BMPR2) promoters. The current study shows that transcriptional repression of these receptors involves Tat interaction with cyclin T1. Assays using U937 human monocytic cells transiently expressing MR or BMPR2 promoter-luciferase constructs demonstrated equal repression by one- and two-exon Tat gene products. A mutant Tat expression vector encoding Tat protein lacking the cyclin T1 binding domain failed to inhibit MR and BMPR2 promoter activities. Over-expression of cyclin T1 in the presence of wild-type Tat resulted in recovered activity from both promoters. Finally, two inhibitors of cyclin-dependent kinase 9 (a dominant negative CDK9 and flavopiridol) repressed activity from the MR and BMPR2 promoters.
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Affiliation(s)
- Robert L Caldwell
- Department of Pathology, Vanderbilt University School of Medicine, Veterans Affairs Medical Center, Nashville, TN, USA
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26
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Gruden-Movsesijan A, Milosavljevic LS. The involvement of the macrophage mannose receptor in the innate immune response to infection with parasite Trichinella spiralis. Vet Immunol Immunopathol 2006; 109:57-67. [PMID: 16135385 DOI: 10.1016/j.vetimm.2005.07.022] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2004] [Revised: 06/16/2005] [Accepted: 07/19/2005] [Indexed: 11/18/2022]
Abstract
The macrophage mannose receptor (MR) is a pattern recognition receptor of the innate immune system that binds to microbial structures bearing mannose, fucose and N-acetylglucosamine on their surface. The MR can mediate endocytosis and phagocytosis, as well as activation of macrophages and antigen presentation. Since Trichinella spiralis antigens are rich in oligomannose residues, we investigated whether a mannose-recognizing receptor, such as the MR, participated in the host-parasite interaction. The results show that the MR (either on the surface of macrophages or in the purified form) recognizes and binds components of T. spiralis muscle larvae. The presence of parasites provoked activation of peritoneal macrophages, which was indicated by down-regulation of MR expression, and the stimulation of NO secretion. In vitro stimulation of macrophages with T. spiralis components resulted in increased NO and IL-6 production. However, while the MR was partially involved in stimulation of NO production, it did not mediate IL-6 secretion.
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Affiliation(s)
- A Gruden-Movsesijan
- Institute for the Application of Nuclear Energy-INEP, Banatska 31b, 11080 Belgrade, Serbia and Montenegro.
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27
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Tachado SD, Zhang J, Zhu J, Patel N, Koziel H. HIV Impairs TNF-α Release in Response to Toll-Like Receptor 4 Stimulation in Human MacrophagesIn Vitro. Am J Respir Cell Mol Biol 2005; 33:610-21. [PMID: 16109884 DOI: 10.1165/rcmb.2004-0341oc] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The molecular mechanisms for increased risk of bacterial pneumonia in HIV+ persons remain incompletely understood. Recognizing the critical role of Toll-like receptor (TLR) signaling in host defense, this study showed that human U937 macrophage stimulation by the TLR4-specific ligand, lipid A (biologically active component of bacterial LPS), promoted TNF-alpha release through extracellular regulated kinase (ERK)1/2 mitogen-activated protein (MAP) kinase phosphorylation. In contrast, HIV+ U1 macrophages had significantly reduced TNF-alpha release (despite preserved TLR4 expression) and reduced ERK1/2 phosphorylation, whereas TNF-alpha release was intact via a TLR4-independent pathway. In HIV+ U1 cells, reduced ERK1/2 phosphorylation was not due to reduced upstream MEK1/2 activation, but was associated with a reciprocal induction of MAP kinase phosphatase-1 (MKP-1). HIV nef protein was sufficient to reduce TNF-alpha release and induce MKP-1 in healthy macrophages. Pharmacologic inhibition of endogenous cellular phosphatases increased ERK1/2 phosphorylation and partially restored TLR4-mediated TNF-alpha release in HIV+ macrophages. Furthermore, targeted gene silencing of MKP-1 partially restored lipid A-mediated TNF-alpha release in HIV+ U1 cells. Similar results were observed using clinically relevant human alveolar macrophages, comparing healthy to asymptomatic HIV+ persons at clinical risk for bacterial pneumonia. Thus, reduced TLR4-mediated TNF-alpha release through altered ERK1/2 regulation by HIV may impair an effective innate immune response to bacterial challenge. Inhibition of cellular phosphatases may serve as a potential therapeutic target in the management of bacterial pneumonia in HIV+ persons.
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Affiliation(s)
- Souvenir D Tachado
- Department of Pulmonary, Critical Care and Sleep Medicine, Kirstein Hall, Room E/KSB-23, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215, USA
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28
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Caldwell RL, Gadipatti R, Lane KB, Shepherd VL. HIV-1 TAT represses transcription of the bone morphogenic protein receptor-2 in U937 monocytic cells. J Leukoc Biol 2005; 79:192-201. [PMID: 16282533 DOI: 10.1189/jlb.0405194] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The bone morphogenetic protein receptor-2 (BMPR2) is a member of the transforming growth factor-beta receptor family and is expressed on the surface of several cell types including endothelial cells and macrophages. Recently, a cause for familial primary pulmonary hypertension (FPPH) has been identified as mutations in the gene encoding BMPR2. Three forms of pulmonary hypertension (PH) exist, including PPH, FPPH, and PH secondary to other etiologies (sporadic PH) such as drug abuse and human immunodeficiency virus (HIV) infection. It is interesting that these subtypes are histologically indistinguishable. The macrophage is a key target cell for HIV-1, significantly altering macrophage cell function upon infection. HIV-1 trans-activator of transcription (Tat), an immediate-early product of the HIV-1 lifecycle, plays an important role in mediating HIV-induced modulation of host cell function. Our laboratory has previously shown that Tat represses mannose receptor transcription in macrophages. In the current study, we examined activity from the BMPR2 promoter in the macrophage cell line U937 and potential regulation by Tat. Transfection of U937 cells with BMPR2 promoter-reporter constructs revealed dose-dependent repression of BMPR2 promoter activity in the presence of Tat. Experiments using truncations of the BMPR2 promoter localized Tat-mediated repression to the first 208 bases of the promoter. Decreased BMPR2 transcription resulted in altered downstream signaling. Similar to mothers against decapentaplegics (SMAD) phosphorylation and SMAD6 expression, in response to BMP2 treatment, were down-regulated after Tat treatment. Finally, HIV-1 infection and treatment with Tat protein of the U937 human monocytic cell line resulted in a decreased, endogenous BMPR2 transcript copy number.
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MESH Headings
- Bone Morphogenetic Protein Receptors, Type II/biosynthesis
- Bone Morphogenetic Protein Receptors, Type II/genetics
- Down-Regulation
- Endothelial Cells/metabolism
- Gene Products, tat/metabolism
- Gene Products, tat/pharmacology
- HIV Infections/genetics
- HIV Infections/metabolism
- HIV-1
- Humans
- Hypertension, Pulmonary/genetics
- Lectins, C-Type/biosynthesis
- Lectins, C-Type/genetics
- Macrophages/metabolism
- Macrophages/virology
- Mannose Receptor
- Mannose-Binding Lectins/biosynthesis
- Mannose-Binding Lectins/genetics
- Mutation
- Phosphorylation
- Protein Processing, Post-Translational
- Receptors, Cell Surface/biosynthesis
- Receptors, Cell Surface/genetics
- Response Elements/genetics
- Signal Transduction
- Smad6 Protein/biosynthesis
- Smad6 Protein/genetics
- U937 Cells
- tat Gene Products, Human Immunodeficiency Virus
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Affiliation(s)
- Robert L Caldwell
- Department of Pathology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
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29
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Bettaccini AA, Baj A, Accolla RS, Basolo F, Toniolo AQ. Proliferative activity of extracellular HIV-1 Tat protein in human epithelial cells: expression profile of pathogenetically relevant genes. BMC Microbiol 2005; 5:20. [PMID: 15857508 PMCID: PMC1090582 DOI: 10.1186/1471-2180-5-20] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2004] [Accepted: 04/27/2005] [Indexed: 02/04/2023] Open
Abstract
Background Tat is being tested as a component of HIV vaccines. Tat activity has been mainly investigated on cells of lymphoid/hematopoietic lineages. HIV-1, however, is known to infect many different cells of both solid organs and mucosal surfaces. The activity of two-exon (aa 1–101) and synthetic (aa 1–86) Tat was studied on mammary and amniotic epithelial cells cultured under low serum conditions. Results small concentrations of Tat (100 ng/ml) stimulated cell proliferation. Tat antibodies neutralized the mitogenic Tat activity. Changes of gene expression in Tat-treated cells were evaluated by RT-PCR and gene-array methods. Within 4 hours of treatment, exposure to Tat is followed by up-regulation of some cell cycle-associated genes (transcription factors, cyclin/cdk complexes, genes of apoptotic pathways) and of genes relevant to HIV pathogenesis [chemokine receptors (CXCR4, CCR3), chemotactic cytokines (SDF-1, RANTES, SCYC1, SCYE1), IL6 family cytokines, inflammatory cytokines, factors of the TGF-beta family (TGFb, BMP-1, BMP-2)]. Up-regulation of anti-inflammatory cytokines (IL-10, IL-19, IL-20), a hallmark of other persistent viral infections, was a remarkable feature of Tat-treated epithelial cell lines. Conclusion extracellular Tat is mitogenic for mammary and amniotic epithelial cells and stimulates the expression of genes of pathogenetic interest in HIV infection. These effects may favor virus replication and may facilitate the mother-to-child transmission of virus.
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Affiliation(s)
- Alessia A Bettaccini
- Dipartimento di Scienze Cliniche e Biologiche, Università dell' Insubria, Varese, Italy
| | - Andreina Baj
- Dipartimento di Scienze Cliniche e Biologiche, Università dell' Insubria, Varese, Italy
| | - Roberto S Accolla
- Dipartimento di Scienze Cliniche e Biologiche, Università dell' Insubria, Varese, Italy
| | - Fulvio Basolo
- Dipartimento di Oncologia, Università di Pisa, Pisa, Italy
| | - Antonio Q Toniolo
- Dipartimento di Scienze Cliniche e Biologiche, Università dell' Insubria, Varese, Italy
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30
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Vigerust DJ, Egan BS, Shepherd VL. HIV-1 Nef mediates post-translational down-regulation and redistribution of the mannose receptor. J Leukoc Biol 2005; 77:522-34. [PMID: 15637102 DOI: 10.1189/jlb.0804454] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Human immunodeficiency virus (HIV) has derived a variety of means to evade the host immune response. HIV-derived proteins, including Tat, Nef, and Env, have all been reported to decrease expression of host molecules such as CD4 and major histocompatibility complex I, which would assist in limiting viral replication. The mannose receptor (MR) on the surface of macrophages and dendritic cells (DC) has been proposed to function as an effective antigen-capture molecule, as well as a receptor for entering pathogens such as Mycobacterium tuberculosis and Pneumocystis carinii. Regulation of this receptor would therefore benefit HIV in removing an additional arm of the innate immune system. Previous work has shown that MR function is reduced in alveolar macrophages from HIV-infected patients and that surface MR levels are decreased by the HIV-derived protein Nef in DC. In addition, several laboratories have shown that CD4 is removed from the surface of T cells in a manner that might be applicable to decreased MR surface expression in macrophages. In the current study, we have investigated the role of Nef in removing MR from the cell surface. We have used a human macrophage cell line stably expressing the MR as well as human epithelial cells transiently expressing CD4 and a unique CD4/MR chimeric molecule constructed from the extracellular and transmembrane domains of CD4 and the cytoplasmic tail portion of the MR. We show that the MR is reduced on the cell surface by approximately 50% in the presence of Nef and that the MR cytoplasmic tail can confer susceptibility to Nef in the CD4/MR chimera. These data suggest that the MR is a potential intracellular target of Nef and that this regulation may represent a mechanism to further cripple the host innate immune system.
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Affiliation(s)
- David J Vigerust
- Department of Pathology, Vanderbilt University, Nashville, Tennessee, USA
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31
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Zhang J, Zhu J, Bu X, Cushion M, Kinane TB, Avraham H, Koziel H. Cdc42 and RhoB activation are required for mannose receptor-mediated phagocytosis by human alveolar macrophages. Mol Biol Cell 2004; 16:824-34. [PMID: 15574879 PMCID: PMC545914 DOI: 10.1091/mbc.e04-06-0463] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Human alveolar macrophages (AMs) phagocytose Pneumocystis (Pc) organisms predominantly through mannose receptors, although the molecular mechanism mediating this opsonin-independent process is not known. In this study, using AMs from healthy individuals, Pc phagocytosis was associated with focal F-actin polymerization and Cdc42, Rac1, and Rho activation in a time-dependent manner. Phagocytosis was primarily dependent on Cdc42 and RhoB activation (as determined by AM transfection with Cdc42 and RhoB dominant-negative alleles) and mediated predominantly through mannose receptors (as determined by siRNA gene silencing of AM mannose receptors). Pc also promoted PAK-1 phosphorylation, which was also dependent on RhoGTPase activation. HIV infection of AMs (as a model for reduced mannose receptor expression and function) was associated with impaired F-actin polymerization, reduced Cdc42 and Rho activation, and markedly reduced PAK-1 phosphorylation in response to Pc organisms. In healthy AMs, Pc phagocytosis was partially dependent on PAK activation, but dependent on the Rho effector molecule ROCK. These data provide a molecular mechanism for AM mannose receptor-mediated phagocytosis of unopsonized Pc organisms that appears distinct from opsonin-dependent phagocytic receptors. Reduced AM mannose receptor-mediated Cdc42 and Rho activation in the context of HIV infection may represent a mechanism that contributes to the pathogenesis of opportunistic pneumonia.
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MESH Headings
- Actins/metabolism
- Adaptor Proteins, Signal Transducing
- Blotting, Western
- Bronchoalveolar Lavage Fluid/cytology
- Bronchoscopy
- Carrier Proteins/genetics
- Carrier Proteins/metabolism
- Cells, Cultured
- Cytoskeletal Proteins
- Enzyme Activation
- Enzyme-Linked Immunosorbent Assay
- Fluorescein-5-isothiocyanate
- Fluorescent Dyes
- Gene Silencing
- HIV Infections/complications
- HIV Infections/immunology
- HIV Infections/virology
- HIV-1/isolation & purification
- Humans
- Immunity, Innate
- Lectins, C-Type/metabolism
- Macrophage Activation
- Macrophages, Alveolar/immunology
- Macrophages, Alveolar/microbiology
- Mannose Receptor
- Mannose-Binding Lectins/metabolism
- Microscopy, Confocal
- Phagocytosis/drug effects
- Phagocytosis/physiology
- Pneumocystis/physiology
- Precipitin Tests
- Protein Serine-Threonine Kinases/metabolism
- RNA, Small Interfering/metabolism
- Receptors, Cell Surface/metabolism
- Tetradecanoylphorbol Acetate/pharmacology
- Transfection
- Zymosan/pharmacology
- cdc42 GTP-Binding Protein/genetics
- cdc42 GTP-Binding Protein/metabolism
- p21-Activated Kinases
- rho GTP-Binding Proteins
- rhoB GTP-Binding Protein/genetics
- rhoB GTP-Binding Protein/metabolism
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Affiliation(s)
- Jianmin Zhang
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02115, USA
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32
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Abstract
Dendritic cells are critical for host immunity and are involved both in the innate and adaptive immune responses. They are among the first cells targeted by HIV-1 in vivo at mucosal sites. Dendritic cells can sequester HIV-1 in endosomal compartments for several days and transmit infectious HIV-1 to interacting T cells in the lymph node, which is the most important site for viral replication and spread. Initially, the cellular immune response developed against HIV-1 is strong, but eventually it fails to control and resolve the infection. The most dramatic effect seen on the immune system during untreated HIV-1 infection is the destruction of helper CD4(+) T cells, which leads to subsequent immune deficiency. However, the immunomodulatory effects of HIV-1 on different dendritic cell subpopulations may also play an important role in the pathogenesis of HIV-1. This review discusses the effects HIV-1 exerts on dendritic cells in vivo and in vitro, including the binding and uptake of HIV by dendritic cells, the formation of infectious synapses, infection, and the role of dendritic cells in HIV-1 pathogenesis.
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Affiliation(s)
- Marie Larsson
- New York University, School of Medicine, 550 First Avenue, MSB 507, New York, NY 10016, USA.
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33
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Becker Y. HIV-1 gp120 binding to dendritic cell receptors mobilize the virus to the lymph nodes, but the induced IL-4 synthesis by FcepsilonRI+ hematopoietic cells damages the adaptive immunity--a review, hypothesis, and implications. Virus Genes 2004; 29:147-65. [PMID: 15215692 DOI: 10.1023/b:viru.0000032797.43537.d3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
HIV-1 is equipped with the envelope gp160 glycoprotein for interaction with Langerhans cells (LCs) and dendritic cells (DCs), the members of the innate immune system, which confront the virus at the portal of virus entry in the human body. These cells are equipped with receptors by which they bind and endocytose the virus. The gp120 glycoprotein is used for binding to CD4 receptor and CCR5 co-receptor of T helper 2 (Th2) cells and the virions shed gp120 is able to induce FcepsilonRI+ hematopoietic cells to produce IL-4, which inactivate the host adaptive immune response. The properties of gp120s various functional domains are analyzed together with the regulatory viral proteins, which are involved in the damage to T and B cells during HIV-1 replication. The interaction of HIV-1 virions through their gp120 with LCs and DCs at the portal of virus entry will be discussed. A hypothesis will be presented that the understanding of the role of the different functional domains of gp120 in the life cycle of the virus and during AIDS will help in the design of approaches to prevent and abrogate HIV-1 infection and AIDS.
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Affiliation(s)
- Yechiel Becker
- Department of Molecular Virology, Faculty of Medicine, the Hebrew University of Jerusalem, P.O. Box 12272, 91120, Israel.
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34
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Calzado MA, Sancho R, Muñoz E. Human immunodeficiency virus type 1 Tat increases the expression of cleavage and polyadenylation specificity factor 73-kilodalton subunit modulating cellular and viral expression. J Virol 2004; 78:6846-54. [PMID: 15194760 PMCID: PMC421638 DOI: 10.1128/jvi.78.13.6846-6854.2004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) Tat protein, which is essential for HIV gene expression and viral replication, is known to mediate pleiotropic effects on various cell functions. For instance, Tat protein is able to regulate the rate of transcription of host cellular genes and to interact with the signaling machinery, leading to cellular dysfunction. To study the effect that HIV-1 Tat exerts on the host cell, we identified several genes that were up- or down-regulated in tat-expressing cell lines by using the differential display method. HIV-1 Tat specifically increases the expression of the cleavage and polyadenylation specificity factor (CPSF) 73-kDa subunit (CPSF3) without affecting the expression of the 160- and 100-kDa subunits of the CPSF complex. This complex comprises four subunits and has a key function in the 3'-end processing of pre-mRNAs by a coordinated interaction with other factors. CPSF3 overexpression experiments and knockdown of the endogenous CPSF3 by mRNA interference have shown that this subunit of the complex is an important regulatory protein for both viral and cellular gene expression. In addition to the known CPSF3 function in RNA polyadenylation, we also present evidence that this protein exerts transcriptional activities by repressing the mdm2 gene promoter. Thus, HIV-1-Tat up-regulation of CPSF3 could represent a novel mechanism by which this virus increases mRNA processing, causing an increase in both cell and viral gene expression.
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Affiliation(s)
- Marco A Calzado
- Departamento de Biología Celular, Fisiología e Inmunología, Facultad de Medicina, Universidad de Córdoba, Cordoba, Spain
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35
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Kim BO, Liu Y, Zhou BY, He JJ. Induction of C chemokine XCL1 (lymphotactin/single C motif-1 alpha/activation-induced, T cell-derived and chemokine-related cytokine) expression by HIV-1 Tat protein. THE JOURNAL OF IMMUNOLOGY 2004; 172:1888-95. [PMID: 14734774 DOI: 10.4049/jimmunol.172.3.1888] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
HIV-1 Tat has been proposed as a key agent in many AIDS-related disorders, including HIV-1-associated neurological diseases. We have recently shown that Tat expression induces a significant increase in T lymphocytes in the brains of Tat transgenic mice. The CNS infiltration of T lymphocytes has been noted in AIDS patients. In the present study using this unique genetic system we attempted to understand the underlying mechanisms of Tat expression-induced infiltration of T lymphocytes by examining chemokine expression. RNase protection assay revealed that in addition to CCL2 (monocyte chemoattractant protein-1), CCL3 (macrophage inflammatory protein-1alpha (MIP-1alpha)), CCL4 (MIP-1beta), CCL5 (RANTES), CXCL2 (MIP-2), and CXCL10 (inducing protein-10), XCL1 (lymphotactin/single C motif-1alpha/activation-induced, T cell-derived and chemokine-related cytokine) was identified to be up-regulated by Tat expression. XCL1 is a C chemokine and plays a specific and important role in tissue-specific recruitment of T lymphocytes. Thus, we further determined the relationship between Tat and XCL1 expression. Tat-induced XCL1 expression was further confirmed by XCL1-specific RT-PCR and ELISA. Combined in situ hybridization and immunohistochemical staining identified astrocytes, monocytes, and macrophages/microglia as XCL1-producing cells in vivo. Using human astrocytes, U87.MG cells, as an in vitro model, activation of XCL1 expression was positively correlated with Tat expression. Moreover, the XCL1 promoter-driven reporter gene assay showed that Tat-induced XCL1 expression occurred at the transcriptional level. Taken together, these results demonstrate that Tat directly trans-activated XCL1 expression and suggest potential roles of Tat-induced XCL1 expression in the CNS infiltration of T lymphocytes during HIV-1 infection and subsequent HIV-1-induced neurological diseases.
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MESH Headings
- Amino Acid Motifs
- Animals
- Astrocytes/immunology
- Astrocytes/metabolism
- Brain/cytology
- Brain/immunology
- Brain/metabolism
- Brain/virology
- Cell Line, Tumor
- Cells, Cultured
- Chemokines, C/biosynthesis
- Chemokines, C/chemistry
- Chemokines, C/genetics
- Gene Expression Regulation
- Gene Products, tat/biosynthesis
- Gene Products, tat/genetics
- Gene Products, tat/physiology
- HIV-1/genetics
- HIV-1/physiology
- Humans
- Lymphocyte Activation
- Lymphokines/chemistry
- Macrophages/immunology
- Macrophages/metabolism
- Mice
- Mice, Transgenic
- Microglia/immunology
- Microglia/metabolism
- Monocytes/immunology
- Monocytes/metabolism
- Promoter Regions, Genetic
- RNA, Messenger/biosynthesis
- Sialoglycoproteins/chemistry
- T-Lymphocytes/immunology
- T-Lymphocytes/metabolism
- Up-Regulation/genetics
- tat Gene Products, Human Immunodeficiency Virus
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Affiliation(s)
- Byung Oh Kim
- Department of Microbiology and Immunology, Walther Oncology Center, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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36
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Liu Y, Liu H, Kim BO, Gattone VH, Li J, Nath A, Blum J, He JJ. CD4-independent infection of astrocytes by human immunodeficiency virus type 1: requirement for the human mannose receptor. J Virol 2004; 78:4120-33. [PMID: 15047828 PMCID: PMC374297 DOI: 10.1128/jvi.78.8.4120-4133.2004] [Citation(s) in RCA: 156] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) infection occurs in the central nervous system and causes a variety of neurobehavioral and neuropathological disorders. Both microglia, the residential macrophages in the brain, and astrocytes are susceptible to HIV-1 infection. Unlike microglia that express and utilize CD4 and chemokine coreceptors CCR5 and CCR3 for HIV-1 infection, astrocytes fail to express CD4. Astrocytes express several chemokine coreceptors; however, the involvement of these receptors in astrocyte HIV-1 infection appears to be insignificant. In the present study using an expression cloning strategy, the cDNA for the human mannose receptor (hMR) was found to be essential for CD4-independent HIV-1 infectivity. Ectopic expression of functional hMR rendered U87.MG astrocytic cells susceptible to HIV-1 infection, whereas anti-hMR serum and hMR-specific siRNA blocked HIV-1 infection in human primary astrocytes. In agreement with these findings, hMR bound to HIV-1 virions via the abundant and highly mannosylated sugar moieties of HIV-1 envelope glycoprotein gp120 in a Ca(2+)-dependent fashion. Moreover, hMR-mediated HIV-1 infection was dependent upon endocytic trafficking as assessed by transmission electron microscopy, as well as inhibition of viral entry by endosomo- and lysosomotropic drugs. Taken together, these results demonstrate the direct involvement of hMR in HIV-1 infection of astrocytes and suggest that HIV-1 interaction with hMR plays an important role in HIV-1 neuropathogenesis.
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Affiliation(s)
- Ying Liu
- Department of Microbiology and Immunology, Walther Oncology Center, Department of Anatomy and Cell Biology, Department of Medicine, Indiana University School of Medicine, Walther Cancer Institute, Indianapolis, Indiana 46202, Department of General Surgery, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, People's Republic of China, Department of Neurology, Johns Hopkins University, Baltimore, Maryland 21287
| | - Hao Liu
- Department of Microbiology and Immunology, Walther Oncology Center, Department of Anatomy and Cell Biology, Department of Medicine, Indiana University School of Medicine, Walther Cancer Institute, Indianapolis, Indiana 46202, Department of General Surgery, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, People's Republic of China, Department of Neurology, Johns Hopkins University, Baltimore, Maryland 21287
| | - Byung Oh Kim
- Department of Microbiology and Immunology, Walther Oncology Center, Department of Anatomy and Cell Biology, Department of Medicine, Indiana University School of Medicine, Walther Cancer Institute, Indianapolis, Indiana 46202, Department of General Surgery, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, People's Republic of China, Department of Neurology, Johns Hopkins University, Baltimore, Maryland 21287
| | - Vincent H. Gattone
- Department of Microbiology and Immunology, Walther Oncology Center, Department of Anatomy and Cell Biology, Department of Medicine, Indiana University School of Medicine, Walther Cancer Institute, Indianapolis, Indiana 46202, Department of General Surgery, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, People's Republic of China, Department of Neurology, Johns Hopkins University, Baltimore, Maryland 21287
| | - Jinliang Li
- Department of Microbiology and Immunology, Walther Oncology Center, Department of Anatomy and Cell Biology, Department of Medicine, Indiana University School of Medicine, Walther Cancer Institute, Indianapolis, Indiana 46202, Department of General Surgery, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, People's Republic of China, Department of Neurology, Johns Hopkins University, Baltimore, Maryland 21287
| | - Avindra Nath
- Department of Microbiology and Immunology, Walther Oncology Center, Department of Anatomy and Cell Biology, Department of Medicine, Indiana University School of Medicine, Walther Cancer Institute, Indianapolis, Indiana 46202, Department of General Surgery, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, People's Republic of China, Department of Neurology, Johns Hopkins University, Baltimore, Maryland 21287
| | - Janice Blum
- Department of Microbiology and Immunology, Walther Oncology Center, Department of Anatomy and Cell Biology, Department of Medicine, Indiana University School of Medicine, Walther Cancer Institute, Indianapolis, Indiana 46202, Department of General Surgery, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, People's Republic of China, Department of Neurology, Johns Hopkins University, Baltimore, Maryland 21287
| | - Johnny J. He
- Department of Microbiology and Immunology, Walther Oncology Center, Department of Anatomy and Cell Biology, Department of Medicine, Indiana University School of Medicine, Walther Cancer Institute, Indianapolis, Indiana 46202, Department of General Surgery, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, People's Republic of China, Department of Neurology, Johns Hopkins University, Baltimore, Maryland 21287
- Corresponding author. Mailing address: Department of Microbiology and Immunology, Indiana University School of Medicine, R2 302, 950 W. Walnut St., Indianapolis, IN 46202. Phone: (317) 274-7525. Fax: (317) 274-7592. E-mail:
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37
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Abstract
The mannose receptor is a transmembrane glycoprotein mainly expressed by macrophages, that specifically binds to mannosylated molecules and mediates their endocytosis. Known ligands of the receptor are lysosomases and various pathogens. Ligand specificity and cellular distribution provide the mannose receptor with a very important role in homeostasis and in the immune response. Expression of the mannose receptor has recently been demonstrated in the brain. Astrocytes and microglia, two types of glial cells that can be turned into immune-competent cells, are the main site of expression in vivo and in vitro. The mannose receptor mediates in vitro pinocytosis by astrocytes and microglia and phagocytosis by microglia. Expression and endocytic activities of the mannose receptor in these cells are regulated by various cytokines. Based on our current knowledge on mannose receptor activities in brain cells, on its regional and temporal expression in that organ, and on its putative ligands therein, the possible involvement of the mannose receptor in brain homeostasis, neuronal functions, and brain defense is discussed.
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Affiliation(s)
- Anne Régnier-Vigouroux
- Applied Tumor Virology, AbtF010/INSERM U375, Deutsches Krebsforschungszentrum, INF 242, 69120, Heidelberg, Germany
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38
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Swain SD, Lee SJ, Nussenzweig MC, Harmsen AG. Absence of the macrophage mannose receptor in mice does not increase susceptibility to Pneumocystis carinii infection in vivo. Infect Immun 2003; 71:6213-21. [PMID: 14573639 PMCID: PMC219593 DOI: 10.1128/iai.71.11.6213-6221.2003] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Host defense against the opportunistic pathogen Pneumocystis carinii requires functional interactions of many cell types. Alveolar macrophages are presumed to be a vital host cell in the clearance of P. carinii, and the mechanisms of this interaction have come under scrutiny. The macrophage mannose receptor is believed to play an important role as a receptor involved in the binding and phagocytosis of P. carinii. Although there is in vitro evidence for this interaction, the in vivo role of this receptor in P. carinii clearance in unclear. Using a mouse model in which the mannose receptor has been deleted, we found that the absence of this receptor is not sufficient to allow infection by P. carinii in otherwise immunocompetent mice. Furthermore, when mice were rendered susceptible to P. carinii by CD4(+) depletion, mannose receptor knockout mice (MR-KO) had pathogen loads equal to those of wild-type mice. However, the MR-KO mice exhibited a greater influx of phagocytes into the alveoli during infection. This was accompanied by increased pulmonary pathology in the MR-KO mice, as well as greater accumulation of glycoproteins in the alveoli (glycoproteins, including harmful hydrolytic enzymes, are normally cleared by the mannose receptor). We also found that the surface expression of the mannose receptor is not downregulated during P. carinii infection in wild-type mice. Our findings suggest that while the macrophage mannose receptor may be important in the recognition of P. carinii, in vivo, this mechanism may be redundant, and the absence of this receptor may be compensated for.
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Affiliation(s)
- Steve D Swain
- Department of Veterinary Molecular Biology, Montana State University, Bozeman, Montana 59717, USA.
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39
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Wahl SM, Greenwell-Wild T, Peng G, Ma G, Orenstein JM, Vazquez N. Viral and host cofactors facilitate HIV-1 replication in macrophages. J Leukoc Biol 2003; 74:726-35. [PMID: 12960226 DOI: 10.1189/jlb.0503220] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) infection of CD4+ T lymphocytes leads to their progressive loss, whereas HIV-1-infected macrophages appear to resist HIV-1-mediated apoptotic death. The differential response of these two host-cell populations may be critical in the development of immunodeficiency and long-term persistence of the virus. Multiple contributing factors may favor the macrophage as a resilient host, not only supporting infection by HIV-1 but also promoting replication and persistence of this member of the lentivirus subfamily of primate retroviruses. An encounter between macrophages and R5 virus engages a signal cascade eventuating in transcriptional regulation of multiple genes including those associated with host defense, cell cycle, nuclear factor-kappaB regulation, and apoptosis. It is important that enhanced gene expression is transient, declining to near control levels, and during this quiescent state, the virus continues its life cycle unimpeded. However, when viral replication becomes prominent, an increase in host genes again occurs under the orchestration of viral gene products. This biphasic host response must fulfill the needs of the parasitic virus as viral replication activity occurs and leads to intracellular and cell surface-associated viral budding. Inroads into understanding how HIV-1 co-opts host factors to generate a permissive environment for viral replication and transmission to new viral hosts may provide opportunities for targeted interruption of this lethal process.
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Affiliation(s)
- Sharon M Wahl
- Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, MD 20892-4352, USA.
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40
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Abstract
Dendritic cells are professional antigen-presenting cells required for generation of adaptive immunity. These cells are one of the initial target cells for HIV-1 infection or capture of virions at site of transmission in the mucosa. DCs carrying HIV-1 will migrate to the lymphoid tissue where they can contribute to the dissemination of the virus to adjacent CD4+ T cells. In addition, HIV-1-exposed DCs may have impaired antigen-presenting capacity resulting in inadequate expansion of HIV-1-specific T cell responses. Here, we review the infection of different subtypes of DCs by HIV-1 and the relevance of these cells in the transmission and establishment of HIV-1 disease. In addition, we discuss the mechanisms through which HIV-1-DC interactions could be exploited to optimise the generation and maintenance of HIV-1-specific T cell immunity.
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Affiliation(s)
- Karin Lore
- Vaccine Research Center, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-3022, USA.
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41
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de la Fuente C, Santiago F, Deng L, Eadie C, Zilberman I, Kehn K, Maddukuri A, Baylor S, Wu K, Lee CG, Pumfery A, Kashanchi F. Gene expression profile of HIV-1 Tat expressing cells: a close interplay between proliferative and differentiation signals. BMC BIOCHEMISTRY 2002; 3:14. [PMID: 12069692 PMCID: PMC116586 DOI: 10.1186/1471-2091-3-14] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2002] [Accepted: 06/10/2002] [Indexed: 11/15/2022]
Abstract
BACKGROUND Expression profiling holds great promise for rapid host genome functional analysis. It is plausible that host expression profiling in an infection could serve as a universal phenotype in virally infected cells. Here, we describe the effect of one of the most critical viral activators, Tat, in HIV-1 infected and Tat expressing cells. We utilized microarray analysis from uninfected, latently HIV-1 infected cells, as well as cells that express Tat, to decipher some of the cellular changes associated with this viral activator. RESULTS Utilizing uninfected, HIV-1 latently infected cells, and Tat expressing cells, we observed that most of the cellular host genes in Tat expressing cells were down-regulated. The down-regulation in Tat expressing cells is most apparent on cellular receptors that have intrinsic receptor tyrosine kinase (RTK) activity and signal transduction members that mediate RTK function, including Ras-Raf-MEK pathway. Co-activators of transcription, such as p300/CBP and SRC-1, which mediate gene expression related to hormone receptor genes, were also found to be down-regulated. Down-regulation of receptors may allow latent HIV-1 infected cells to either hide from the immune system or avoid extracellular differentiation signals. Some of the genes that were up-regulated included co-receptors for HIV-1 entry, translation machinery, and cell cycle regulatory proteins. CONCLUSIONS We have demonstrated, through a microarray approach, that HIV-1 Tat is able to regulate many cellular genes that are involved in cell signaling, translation and ultimately control the host proliferative and differentiation signals.
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Affiliation(s)
- Cynthia de la Fuente
- Department of Biochemistry and Molecular Biology George Washington University School of Medicine Washington DC, 20037, USA
| | - Francisco Santiago
- Department of Biochemistry and Molecular Biology George Washington University School of Medicine Washington DC, 20037, USA
| | - Longwen Deng
- Department of Biochemistry and Molecular Biology George Washington University School of Medicine Washington DC, 20037, USA
| | - Carolyne Eadie
- Department of Biochemistry and Molecular Biology George Washington University School of Medicine Washington DC, 20037, USA
| | - Irene Zilberman
- Department of Biochemistry and Molecular Biology George Washington University School of Medicine Washington DC, 20037, USA
| | - Kylene Kehn
- Department of Biochemistry and Molecular Biology George Washington University School of Medicine Washington DC, 20037, USA
| | - Anil Maddukuri
- Department of Biochemistry and Molecular Biology George Washington University School of Medicine Washington DC, 20037, USA
| | - Shanese Baylor
- Department of Biochemistry and Molecular Biology George Washington University School of Medicine Washington DC, 20037, USA
| | - Kaili Wu
- Department of Biochemistry and Molecular Biology George Washington University School of Medicine Washington DC, 20037, USA
| | - Chee Gun Lee
- Department of Biochemistry and Molecular Biology UMDNJ-New Jersey Medical School Newark, NJ 07103, USA
| | - Anne Pumfery
- Department of Biochemistry and Molecular Biology George Washington University School of Medicine Washington DC, 20037, USA
| | - Fatah Kashanchi
- Department of Biochemistry and Molecular Biology George Washington University School of Medicine Washington DC, 20037, USA
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42
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Poggi A, Carosio R, Rubartelli A, Zocchi MR. β
3
‐Mediated engulfment of apoptotic tumor cells by dendritic cells is dependent on CAMKII: inhibition by HIV‐1 Tat. J Leukoc Biol 2002. [DOI: 10.1189/jlb.71.3.531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Alessandro Poggi
- Laboratory of Immunology and National Cancer Research Institute, Genoa, Italy
| | - Roberta Carosio
- Laboratory of Immunology and National Cancer Research Institute, Genoa, Italy
| | - Anna Rubartelli
- Unit of Protein Biology, National Cancer Research Institute, Genoa, Italy; and
| | - Maria Raffaella Zocchi
- Unit of Protein Biology, National Cancer Research Institute, Genoa, Italy; and
- Laboratory of Tumor Immunology, Scientific Institute San Raffaele, Milan, Italy
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43
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Lieberman J, Shankar P, Manjunath N, Andersson J. Dressed to kill? A review of why antiviral CD8 T lymphocytes fail to prevent progressive immunodeficiency in HIV-1 infection. Blood 2001; 98:1667-77. [PMID: 11535496 DOI: 10.1182/blood.v98.6.1667] [Citation(s) in RCA: 178] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CD8 T cells play an important role in protection and control of HIV-1 by direct cytolysis of infected cells and by suppression of viral replication by secreted factors. However, although HIV-1-infected individuals have a high frequency of HIV-1-specific CD8 T cells, viral reservoirs persist and progressive immunodeficiency generally ensues in the absence of continuous potent antiviral drugs. Freshly isolated HIV-specific CD8 T cells are often unable to lyse HIV-1-infected cells. Maturation into competent cytotoxic T lymphocytes may be blocked during the initial encounter with antigen because of defects in antigen presentation by interdigitating dendritic cells or HIV-infected macrophages. The molecular basis for impaired function is multifactorial, due to incomplete T-cell signaling and activation (in part related to CD3zeta and CD28 down-modulation), reduced perforin expression, and inefficient trafficking of HIV-specific CD8 T cells to lymphoid sites of infection. CD8 T-cell dysfunction can partially be corrected in vitro with short-term exposure to interleukin 2, suggesting that impaired HIV-specific CD4 T helper function may play a significant causal or exacerbating role. Functional defects are qualitatively different and more severe with advanced disease, when interferon gamma production also becomes compromised.
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Affiliation(s)
- J Lieberman
- Center for Blood Research, Harvard Medical School, Boston, MA 02115, USA.
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