1
|
Moezpoor MR, Stevenson M. Help or Hinder: Protein Host Factors That Impact HIV-1 Replication. Viruses 2024; 16:1281. [PMID: 39205255 PMCID: PMC11360189 DOI: 10.3390/v16081281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2024] [Revised: 08/05/2024] [Accepted: 08/08/2024] [Indexed: 09/04/2024] Open
Abstract
Interactions between human immunodeficiency virus type 1 (HIV-1) and the host factors or restriction factors of its target cells determine the cell's susceptibility to, and outcome of, infection. Factors intrinsic to the cell are involved at every step of the HIV-1 replication cycle, contributing to productive infection and replication, or severely attenuating the chances of success. Furthermore, factors unique to certain cell types contribute to the differences in infection between these cell types. Understanding the involvement of these factors in HIV-1 infection is a key requirement for the development of anti-HIV-1 therapies. As the list of factors grows, and the dynamic interactions between these factors and the virus are elucidated, comprehensive and up-to-date summaries that recount the knowledge gathered after decades of research are beneficial to the field, displaying what is known so that researchers can build off the groundwork of others to investigate what is unknown. Herein, we aim to provide a review focusing on protein host factors, both well-known and relatively new, that impact HIV-1 replication in a positive or negative manner at each stage of the replication cycle, highlighting factors unique to the various HIV-1 target cell types where appropriate.
Collapse
Affiliation(s)
- Michael Rameen Moezpoor
- Department of Microbiology and Immunology, University of Miami Leonard M. Miller School of Medicine, Miami, FL 33136, USA
| | - Mario Stevenson
- Raymond F. Schinazi and Family Endowed Chair in Biomedicine; Professor of Medicine; Director, Institute of AIDS and Emerging Infectious Diseases; Department of Microbiology and Immunology, University of Miami Leonard M. Miller School of Medicine, Life Science Technology Park, 1951 NW 7th Avenue, Room 2331B, Suite 200, Miami, FL 33136, USA;
| |
Collapse
|
2
|
Borrajo López A, Penedo MA, Rivera-Baltanas T, Pérez-Rodríguez D, Alonso-Crespo D, Fernández-Pereira C, Olivares JM, Agís-Balboa RC. Microglia: The Real Foe in HIV-1-Associated Neurocognitive Disorders? Biomedicines 2021; 9:925. [PMID: 34440127 PMCID: PMC8389599 DOI: 10.3390/biomedicines9080925] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 07/19/2021] [Accepted: 07/26/2021] [Indexed: 12/21/2022] Open
Abstract
The current use of combined antiretroviral therapy (cART) is leading to a significant decrease in deaths and comorbidities associated with human immunodeficiency virus type 1 (HIV-1) infection. Nonetheless, none of these therapies can extinguish the virus from the long-lived cellular reservoir, including microglia, thereby representing an important obstacle to curing HIV. Microglia are the foremost cells infected by HIV-1 in the central nervous system (CNS) and are believed to be involved in the development of HIV-1-associated neurocognitive disorder (HAND). At present, the pathological mechanisms contributing to HAND remain unclear, but evidence suggests that removing these infected cells from the brain, as well as obtaining a better understanding of the specific molecular mechanisms of HIV-1 latency in these cells, should help in the design of new strategies to prevent HAND and achieve a cure for these diseases. The goal of this review was to study the current state of knowledge of the neuropathology and research models of HAND containing virus susceptible target cells (microglial cells) and potential pharmacological treatment approaches under investigation.
Collapse
Affiliation(s)
- Ana Borrajo López
- Department of Microbiology and Parasitology, Faculty of Pharmacy, Complutense University of Madrid, 28040 Madrid, Spain
- Department of Experimental Medicine and Surgery, University of Rome Tor Vergata, 00133 Roma, Italy
| | - Maria Aránzazu Penedo
- Translational Neuroscience Group-CIBERSAM, Galicia Sur Health Research Institute (IIS Galicia Sur), Área Sanitaria de Vigo-Hospital Álvaro Cunqueiro, SERGAS-UVIGO, 36213 Vigo, Spain; (M.A.P.); (T.R.-B.); (D.P.-R.); (C.F.-P.); (J.M.O.)
- Neuro Epigenetics Laboratory, University Hospital Complex of Vigo, SERGAS-UVIGO, 36213 Virgo, Spain
| | - Tania Rivera-Baltanas
- Translational Neuroscience Group-CIBERSAM, Galicia Sur Health Research Institute (IIS Galicia Sur), Área Sanitaria de Vigo-Hospital Álvaro Cunqueiro, SERGAS-UVIGO, 36213 Vigo, Spain; (M.A.P.); (T.R.-B.); (D.P.-R.); (C.F.-P.); (J.M.O.)
| | - Daniel Pérez-Rodríguez
- Translational Neuroscience Group-CIBERSAM, Galicia Sur Health Research Institute (IIS Galicia Sur), Área Sanitaria de Vigo-Hospital Álvaro Cunqueiro, SERGAS-UVIGO, 36213 Vigo, Spain; (M.A.P.); (T.R.-B.); (D.P.-R.); (C.F.-P.); (J.M.O.)
- Neuro Epigenetics Laboratory, University Hospital Complex of Vigo, SERGAS-UVIGO, 36213 Virgo, Spain
| | - David Alonso-Crespo
- Nursing Team-Intensive Care Unit, Área Sanitaria de Vigo, Estrada de Clara Campoamor 341, SERGAS-UVigo, 36312 Virgo, Spain;
| | - Carlos Fernández-Pereira
- Translational Neuroscience Group-CIBERSAM, Galicia Sur Health Research Institute (IIS Galicia Sur), Área Sanitaria de Vigo-Hospital Álvaro Cunqueiro, SERGAS-UVIGO, 36213 Vigo, Spain; (M.A.P.); (T.R.-B.); (D.P.-R.); (C.F.-P.); (J.M.O.)
- Neuro Epigenetics Laboratory, University Hospital Complex of Vigo, SERGAS-UVIGO, 36213 Virgo, Spain
| | - José Manuel Olivares
- Translational Neuroscience Group-CIBERSAM, Galicia Sur Health Research Institute (IIS Galicia Sur), Área Sanitaria de Vigo-Hospital Álvaro Cunqueiro, SERGAS-UVIGO, 36213 Vigo, Spain; (M.A.P.); (T.R.-B.); (D.P.-R.); (C.F.-P.); (J.M.O.)
- Department of Psychiatry, Área Sanitaria de Vigo, Estrada de Clara Campoamor 341, SERGAS-UVigo, 36312 Vigo, Spain
| | - Roberto Carlos Agís-Balboa
- Translational Neuroscience Group-CIBERSAM, Galicia Sur Health Research Institute (IIS Galicia Sur), Área Sanitaria de Vigo-Hospital Álvaro Cunqueiro, SERGAS-UVIGO, 36213 Vigo, Spain; (M.A.P.); (T.R.-B.); (D.P.-R.); (C.F.-P.); (J.M.O.)
| |
Collapse
|
3
|
Kruize Z, Kootstra NA. The Role of Macrophages in HIV-1 Persistence and Pathogenesis. Front Microbiol 2019; 10:2828. [PMID: 31866988 PMCID: PMC6906147 DOI: 10.3389/fmicb.2019.02828] [Citation(s) in RCA: 106] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 11/21/2019] [Indexed: 12/12/2022] Open
Abstract
Current antiretroviral therapy (ART) effectively suppresses Human Immunodeficiency Virus type 1 (HIV-1) in infected individuals. However, even long term ART does not eradicate HIV-1 infected cells and the virus persists in cellular reservoirs. Beside memory CD4+ T cells, cells of the myeloid lineage, especially macrophages, are believed to be an important sanctuary for HIV-1. Monocytes and macrophages are key players in the innate immune response to pathogens and are recruited to sites of infection and inflammation. Due to their long life span and ability to reside in virtually every tissue, macrophages have been proposed to play a critical role in the establishment and persistence of the HIV-1 reservoir. Current HIV-1 cure strategies mainly focus on the concept of “shock and kill” to purge the viral reservoir. This approach aims to reactivate viral protein production in latently infected cells, which subsequently are eliminated as a consequence of viral replication, or recognized and killed by the immune system. Macrophage susceptibility to HIV-1 infection is dependent on the local microenvironment, suggesting that molecular pathways directing differentiation and polarization are involved. Current latency reversing agents (LRA) are mainly designed to reactivate the HIV-1 provirus in CD4+ T cells, while their ability to abolish viral latency in macrophages is largely unknown. Moreover, the resistance of macrophages to HIV-1 mediated kill and the presence of infected macrophages in immune privileged regions including the central nervous system (CNS), may pose a barrier to elimination of infected cells by current “shock and kill” strategies. This review focusses on the role of monocytes/macrophages in HIV-1 persistence. We will discuss mechanisms of viral latency and persistence in monocytes/macrophages. Furthermore, the role of these cells in HIV-1 tissue distribution and pathogenesis will be discussed.
Collapse
Affiliation(s)
- Zita Kruize
- Laboratory for Viral Immune Pathogenesis, Department of Experimental Immunology, Amsterdam UMC, Amsterdam Infection & Immunity Institute, University of Amsterdam, Amsterdam, Netherlands
| | - Neeltje A Kootstra
- Laboratory for Viral Immune Pathogenesis, Department of Experimental Immunology, Amsterdam UMC, Amsterdam Infection & Immunity Institute, University of Amsterdam, Amsterdam, Netherlands
| |
Collapse
|
4
|
Timilsina U, Ghimire D, Sharma S, Gaur R. Role of APOBEC3 proteins in proteasome inhibitor-mediated reactivation of latent HIV-1 viruses. J Gen Virol 2019; 100:523-532. [PMID: 30566069 DOI: 10.1099/jgv.0.001205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Proteasome inhibitors (PIs) have been identified as an emerging class of HIV-1 latency-reversing agents (LRAs). These inhibitors can reactivate latent HIV-1 to produce non-infectious viruses. The mechanism underlying reduced infectivity of reactivated viruses is unknown. In this study, we analysed PI-reactivated viruses using biochemical and virological assays and demonstrated that these PIs stabilized the cellular expression of HIV-1 restriction factor, APOBEC3G, facilitating its packaging in the released viruses. Using infectivity assay and immunoblotting, we observed that the reduction in viral infectivity was due to enhanced levels of functionally active APOBEC3 proteins packaged in the virions. Sequencing of the proviral genome in the target cells revealed the presence of APOBEC3 signature hypermutations. Our study strengthens the role of PIs as bifunctional LRAs and demonstrates that the loss of infectivity of reactivated HIV-1 virions may be due to the increased packaging of APOBEC3 proteins in the virus.
Collapse
Affiliation(s)
- Uddhav Timilsina
- Faculty of Life Sciences and Biotechnology, South Asian University, New Delhi-110021, Delhi
| | - Dibya Ghimire
- Faculty of Life Sciences and Biotechnology, South Asian University, New Delhi-110021, Delhi
| | - Shilpa Sharma
- Faculty of Life Sciences and Biotechnology, South Asian University, New Delhi-110021, Delhi
| | - Ritu Gaur
- Faculty of Life Sciences and Biotechnology, South Asian University, New Delhi-110021, Delhi
| |
Collapse
|
5
|
Abstract
Current antiretroviral therapy (ART) effectively suppresses Human Immunodeficiency Virus type 1 (HIV-1) in infected individuals. However, even long term ART does not eradicate HIV-1 infected cells and the virus persists in cellular reservoirs. Beside memory CD4+ T cells, cells of the myeloid lineage, especially macrophages, are believed to be an important sanctuary for HIV-1. Monocytes and macrophages are key players in the innate immune response to pathogens and are recruited to sites of infection and inflammation. Due to their long life span and ability to reside in virtually every tissue, macrophages have been proposed to play a critical role in the establishment and persistence of the HIV-1 reservoir. Current HIV-1 cure strategies mainly focus on the concept of "shock and kill" to purge the viral reservoir. This approach aims to reactivate viral protein production in latently infected cells, which subsequently are eliminated as a consequence of viral replication, or recognized and killed by the immune system. Macrophage susceptibility to HIV-1 infection is dependent on the local microenvironment, suggesting that molecular pathways directing differentiation and polarization are involved. Current latency reversing agents (LRA) are mainly designed to reactivate the HIV-1 provirus in CD4+ T cells, while their ability to abolish viral latency in macrophages is largely unknown. Moreover, the resistance of macrophages to HIV-1 mediated kill and the presence of infected macrophages in immune privileged regions including the central nervous system (CNS), may pose a barrier to elimination of infected cells by current "shock and kill" strategies. This review focusses on the role of monocytes/macrophages in HIV-1 persistence. We will discuss mechanisms of viral latency and persistence in monocytes/macrophages. Furthermore, the role of these cells in HIV-1 tissue distribution and pathogenesis will be discussed.
Collapse
Affiliation(s)
- Zita Kruize
- Laboratory for Viral Immune Pathogenesis, Department of Experimental Immunology, Amsterdam UMC, Amsterdam Infection & Immunity Institute, University of Amsterdam, Amsterdam, Netherlands
| | - Neeltje A Kootstra
- Laboratory for Viral Immune Pathogenesis, Department of Experimental Immunology, Amsterdam UMC, Amsterdam Infection & Immunity Institute, University of Amsterdam, Amsterdam, Netherlands
| |
Collapse
|
6
|
Kumar A, Abbas W, Herbein G. HIV-1 latency in monocytes/macrophages. Viruses 2014; 6:1837-60. [PMID: 24759213 PMCID: PMC4014723 DOI: 10.3390/v6041837] [Citation(s) in RCA: 153] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Revised: 03/11/2014] [Accepted: 03/28/2014] [Indexed: 12/24/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) targets CD4+ T cells and cells of the monocyte/macrophage lineage. HIV pathogenesis is characterized by the depletion of T lymphocytes and by the presence of a population of cells in which latency has been established called the HIV-1 reservoir. Highly active antiretroviral therapy (HAART) has significantly improved the life of HIV-1 infected patients. However, complete eradication of HIV-1 from infected individuals is not possible without targeting latent sources of infection. HIV-1 establishes latent infection in resting CD4+ T cells and findings indicate that latency can also be established in the cells of monocyte/macrophage lineage. Monocyte/macrophage lineage includes among others, monocytes, macrophages and brain resident macrophages. These cells are relatively more resistant to apoptosis induced by HIV-1, thus are important stable hideouts of the virus. Much effort has been made in the direction of eliminating HIV-1 resting CD4+ T-cell reservoirs. However, it is impossible to achieve a cure for HIV-1 without considering these neglected latent reservoirs, the cells of monocyte/macrophage lineage. In this review we will describe our current understanding of the mechanism of latency in monocyte/macrophage lineage and how such cells can be specifically eliminated from the infected host.
Collapse
Affiliation(s)
- Amit Kumar
- UPRES EA4266, SFR FED 4234, Pathogens and Inflammation Laboratory, Department of Virology, CHRU Besançon, University of Franche-Comte, F-25030 Besançon, France.
| | - Wasim Abbas
- UPRES EA4266, SFR FED 4234, Pathogens and Inflammation Laboratory, Department of Virology, CHRU Besançon, University of Franche-Comte, F-25030 Besançon, France.
| | - Georges Herbein
- UPRES EA4266, SFR FED 4234, Pathogens and Inflammation Laboratory, Department of Virology, CHRU Besançon, University of Franche-Comte, F-25030 Besançon, France.
| |
Collapse
|
7
|
Strebel K. HIV accessory proteins versus host restriction factors. Curr Opin Virol 2013; 3:692-9. [PMID: 24246762 PMCID: PMC3855913 DOI: 10.1016/j.coviro.2013.08.004] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 08/05/2013] [Accepted: 08/06/2013] [Indexed: 02/05/2023]
Abstract
Primate immunodeficiency viruses, including HIV-1, are characterized by the presence of accessory genes such as vif, vpr, vpx, vpu, and nef. Current knowledge indicates that none of the primate lentiviral accessory proteins has enzymatic activity. Instead, these proteins interact with cellular ligands to either act as adapter molecules to redirect the normal function of host factors for virus-specific purposes or to inhibit a normal host function by mediating degradation or causing intracellular mislocalization/sequestration of the factors involved. This review aims at providing an update of our current understanding of how Vif, Vpu, and Vpx control the cellular restriction factors APOBEC3G, BST-2, and SAMHD1, respectively.
Collapse
Affiliation(s)
- Klaus Strebel
- Laboratory of Molecular Microbiology, Viral Biochemistry Section, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD 20892-0460, United States.
| |
Collapse
|
8
|
Imahashi M, Nakashima M, Iwatani Y. Antiviral Mechanism and Biochemical Basis of the Human APOBEC3 Family. Front Microbiol 2012; 3:250. [PMID: 22787460 PMCID: PMC3391693 DOI: 10.3389/fmicb.2012.00250] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Accepted: 06/21/2012] [Indexed: 12/24/2022] Open
Abstract
The human APOBEC3 (A3) family (A, B, C, DE, F, G, and H) comprises host defense factors that potently inhibit the replication of diverse retroviruses, retrotransposons, and the other viral pathogens. HIV-1 has a counterstrategy that includes expressing the Vif protein to abrogate A3 antiviral function. Without Vif, A3 proteins, particularly APOBEC3G (A3G) and APOBEC3F (A3F), inhibit HIV-1 replication by blocking reverse transcription and/or integration and hypermutating nascent viral cDNA. The molecular mechanisms of this antiviral activity have been primarily attributed to two biochemical characteristics common to A3 proteins: catalyzing cytidine deamination in single-stranded DNA (ssDNA) and a nucleic acid-binding capability that is specific to ssDNA or ssRNA. Recent advances suggest that unique property of A3G dimer/oligomer formations, is also important for the modification of antiviral activity. In this review article we summarize how A3 proteins, particularly A3G, inhibit viral replication based on the biochemical and structural characteristics of the A3G protein.
Collapse
Affiliation(s)
- Mayumi Imahashi
- Clinical Research Center, National Hospital Organization Nagoya Medical Center Nagoya, Japan
| | | | | |
Collapse
|
9
|
Duncan CJA, Sattentau QJ. Viral determinants of HIV-1 macrophage tropism. Viruses 2011; 3:2255-79. [PMID: 22163344 PMCID: PMC3230851 DOI: 10.3390/v3112255] [Citation(s) in RCA: 46] [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: 09/16/2011] [Revised: 11/04/2011] [Accepted: 11/04/2011] [Indexed: 01/23/2023] Open
Abstract
Macrophages are important target cells for HIV-1 infection that play significant roles in the maintenance of viral reservoirs and other aspects of pathogenesis. Understanding the determinants of HIV-1 tropism for macrophages will inform HIV-1 control and eradication strategies. Tropism for macrophages is both qualitative (infection or not) and quantitative (replication capacity). For example many R5 HIV-1 isolates cannot infect macrophages, but for those that can the macrophage replication capacity can vary by up to 1000-fold. Some X4 viruses are also capable of replication in macrophages, indicating that cellular tropism is partially independent of co-receptor preference. Preliminary data obtained with a small number of transmitted/founder viruses indicate inefficient macrophage infection, whereas isolates from later in disease are more frequently tropic for macrophages. Thus tropism may evolve over time, and more macrophage tropic viruses may be implicated in the pathogenesis of advanced HIV-1 infection. Compartmentalization of macrophage-tropic brain-derived envelope glycoproteins (Envs), and non-macrophage tropic non-neural tissue-derived Envs points to adaptation of HIV-1 quasi-species in distinct tissue microenvironments. Mutations within and adjacent to the Env-CD4 binding site have been identified that determine macrophage tropism at the entry level, but post-entry molecular determinants of macrophage replication capacity involving HIV-1 accessory proteins need further definition.
Collapse
|
10
|
Abstract
APOBEC3F (A3F) is a member of the family of cytidine deaminases that is often coexpressed with APOBEC3G (A3G) in cells susceptible to HIV infection. A3F has been shown to have strong antiviral activity in transient-expression studies, and together with A3G, it is considered the most potent cytidine deaminase targeting HIV. Previous analyses suggested that the antiviral properties of A3F can be dissociated from its catalytic deaminase activity. We were able to confirm the deaminase-independent antiviral activity of exogenously expressed A3F; however, we also noted that exogenous expression was associated with very high A3F mRNA and protein levels. In analogy to our previous study of A3G, we produced stable HeLa cell lines constitutively expressing wild-type or deaminase-defective A3F at levels that were more in line with the levels of endogenous A3F in H9 cells. A3F expressed in stable HeLa cells was packaged into Vif-deficient viral particles with an efficiency similar to that of A3G and was properly targeted to the viral nucleoprotein complex. Surprisingly, however, neither wild-type nor deaminase-defective A3F inhibited HIV-1 infectivity. These results imply that the antiviral activity of endogenous A3F is negligible compared to that of A3G.
Collapse
|
11
|
Harjes E, Gross PJ, Chen KM, Lu Y, Shindo K, Nowarski R, Gross JD, Kotler M, Harris RS, Matsuo H. An extended structure of the APOBEC3G catalytic domain suggests a unique holoenzyme model. J Mol Biol 2009; 389:819-32. [PMID: 19389408 DOI: 10.1016/j.jmb.2009.04.031] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Revised: 04/15/2009] [Accepted: 04/16/2009] [Indexed: 01/27/2023]
Abstract
Human APOBEC3G (A3G) belongs to a family of polynucleotide cytidine deaminases. This family includes APOBEC1 and AID, which edit APOB mRNA and antibody gene DNA, respectively. A3G deaminates cytidines to uridines in single-strand DNA and inhibits the replication of human immunodeficiency virus-1, other retroviruses, and retrotransposons. Although the mechanism of A3G-catalyzed DNA deamination has been investigated genetically and biochemically, atomic details are just starting to emerge. Here, we compare the DNA cytidine deaminase activities and NMR structures of two A3G catalytic domain constructs. The longer A3G191-384 protein is considerably more active than the shorter A3G198-384 variant. The longer structure has an alpha1-helix (residues 201-206) that was not apparent in the shorter protein, and it contributes to catalytic activity through interactions with hydrophobic core structures (beta1, beta3, alpha5, and alpha6). Both A3G catalytic domain solution structures have a discontinuous beta2 region that is clearly different from the continuous beta2 strand of another family member, APOBEC2. In addition, the longer A3G191-384 structure revealed part of the N-terminal pseudo-catalytic domain, including the interdomain linker and some of the last alpha-helix. These structured residues (residues 191-196) enabled a novel full-length A3G model by providing physical overlap between the N-terminal pseudo-catalytic domain and the new C-terminal catalytic domain structure. Contrary to predictions, this structurally constrained model suggested that the two domains are tethered by structured residues and that the N- and C-terminal beta2 regions are too distant from each other to participate in this interaction.
Collapse
Affiliation(s)
- Elena Harjes
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, 55455, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Vpu enhances HIV-1 virus release in the absence of Bst-2 cell surface down-modulation and intracellular depletion. Proc Natl Acad Sci U S A 2009; 106:2868-73. [PMID: 19196977 DOI: 10.1073/pnas.0813223106] [Citation(s) in RCA: 190] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
HIV-1 Vpu enhances the release of virions from infected cells. Recent work identified Bst-2/CD317/tetherin as a host factor whose inhibitory activity on viral release is counteracted by Vpu. A current working model proposes that Bst-2 inhibits virus release by tethering viral particles to the cell surface. Here, we analyzed endogenous Bst-2 with respect to its effect on virus release from HeLa cells, T cells, and macrophages. We noted significant cell type-dependent variation in Bst-2 expression. Vpu caused a reduction in Bst-2 expression in transfected HeLa cells and long-term infected macrophages. However, Vpu expression did not result in cell surface down-modulation of Bst-2 or a reduction in intracellular Bst-2 expression in CEMx174 or H9 cells, yet virus replication in these cells was Vpu-responsive. Surprisingly, Bst-2 was undetectable in cell-free virions that were recovered from the surface of HeLa cells by physical shearing, suggesting that a tethering model may not explain all of the functional properties of Bst-2. Taken together we conclude that enhancement of virus release by Vpu does not, at least in CEMx174 and H9 cells, require cell surface down-modulation or intracellular depletion of Bst-2, nor does it entail exclusion of Bst-2 from viral particles.
Collapse
|
13
|
Differential sensitivity of "old" versus "new" APOBEC3G to human immunodeficiency virus type 1 vif. J Virol 2008; 83:1156-60. [PMID: 19004939 DOI: 10.1128/jvi.01734-08] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
HIV-1 Vif counteracts the antiviral activity of APOBEC3G by inhibiting its encapsidation into virions. Here, we compared the relative sensitivity to Vif of APOBEC3G in stable HeLa cells containing APOBEC3G (HeLa-A3G cells) versus that of newly synthesized APOBEC3G. We observed that newly synthesized APOBEC3G was more sensitive to degradation than preexisting APOBEC3G. Nevertheless, preexisting and transiently expressed APOBEC3G were packaged with similar efficiencies into vif-deficient human immunodeficiency virus type 1 (HIV-1) virions, and Vif inhibited the encapsidation of both forms of APOBEC3G into HIV particles equally well. Our results suggest that HIV-1 Vif preferentially induces degradation of newly synthesized APOBEC3G but indiscriminately inhibits encapsidation of "old" and "new" APOBEC3G.
Collapse
|