1
|
Sonela N, Mann J, Godwe C, Goni OH, Tchakoute M, Nkoue N, de Oliveira T, Brockman MA, Brumme ZL, Ndung'u T, Tongo M. No detectable differences in Nef-mediated downregulation of HLA-I and CD4 molecules among HIV-1 group M lineages circulating in Cameroon, where the pandemic originated. FRONTIERS IN VIROLOGY (LAUSANNE, SWITZERLAND) 2024; 4:fviro.2024.1379217. [PMID: 38883214 PMCID: PMC7616105 DOI: 10.3389/fviro.2024.1379217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
HIV-1 group M (HIV-1M) lineages downregulate HLA-I and CD4 expression via their Nef proteins. We hypothesized that these Nef functions may be partially responsible for the differences in prevalence of viruses from different lineages that co-circulate within an epidemic. Here, we characterized these two Nef activities in HIV-1M isolates from Cameroon, where multiple variants have been circulating since the pandemic's origin. Single HIV-1 Nef clones from 234 HIV-1-ART naïve individuals living in remote villages and two cosmopolitan cities of Cameroon, sampled between 2000 and 2013, were isolated from plasma HIV RNA and analyzed for their capacity to downregulate HLA-I and CD4 molecules. We found that, despite a large degree of within- and inter- lineage variation, the ability of Nef to downregulate HLA-I was similar across these different viruses. Moreover, Nef-mediated CD4 downregulation activity was also well conserved across the different lineages found in Cameroon. In addition, we observed a trend towards higher HLA-I downregulation activity of viruses circulating in the cosmopolitan cities versus the remote villages, whereas the CD4 downregulation activities were similar across the two settings. Furthermore, we noted a significant decline of HLA-I downregulation activity from 2000 to 2013, providing additional evidence supporting the attenuation of the global HIV-1M population over time. Finally, we identified 18 amino acids associated with differential HLA-I downregulation and 13 amino acids associated with differential CD4 downregulation within the dominant CRF02_AG lineage. Our lack of observation of HIV lineage-related differences in Nef-mediated HLA-I and CD4 downregulation function suggests that these activities do not substantively influence the prevalence of different HIV-1M lineages in Cameroon.
Collapse
Affiliation(s)
- Nelson Sonela
- Center of Research for Emerging and Re-Emerging Diseases (CREMER), Institute of Medical Research and Study of Medicinal Plants (IMPM), Yaoundé, Cameroon
- Chantal BIYA International Reference Centre for Research on HIV/AIDS prevention and management (CIRCB), Yaoundé, Cameroon
- Department of Medicine, Weill Cornell Medical College, Cornell University, New York, NY, United States
| | - Jaclyn Mann
- HIV Pathogenesis Programme, University of KwaZulu-Natal, Durban, South Africa
| | - Celestin Godwe
- Center of Research for Emerging and Re-Emerging Diseases (CREMER), Institute of Medical Research and Study of Medicinal Plants (IMPM), Yaoundé, Cameroon
- Départment of Biochemistry, University of Douala, Douala, Cameroon
| | - Oumarou H Goni
- Center of Research for Emerging and Re-Emerging Diseases (CREMER), Institute of Medical Research and Study of Medicinal Plants (IMPM), Yaoundé, Cameroon
- Départment of Microbiology, Faculty of Sciences, University of Yaoundé 1, Yaoundé, Cameroon
| | - Mérime Tchakoute
- Programmes de Santé et développement au sein du Groupement de la Filière Bois du Cameroun, Yaoundé, Cameroon
| | - Nathalie Nkoue
- Programmes de Santé et développement au sein du Groupement de la Filière Bois du Cameroun, Yaoundé, Cameroon
| | - Tulio de Oliveira
- Centre for Epidemic Response and Innovation (CERI), School of Data Science and Computational Thinking, Stellenbosch University, Stellenbosch, South Africa
- KwaZulu-Natal Research Innovation and Sequencing Platform (KRISP), School of Laboratory Medicine and Medical Sciences, College of Health Sciences, Nelson R Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa
| | - Mark A Brockman
- Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
- Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada
- British Columbia Centre for Excellence in HIV/AIDS, Vancouver, BC, Canada
| | - Zabrina L Brumme
- Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada
- British Columbia Centre for Excellence in HIV/AIDS, Vancouver, BC, Canada
| | - Thumbi Ndung'u
- HIV Pathogenesis Programme, University of KwaZulu-Natal, Durban, South Africa
- Max Planck Institute for Infection Biology, Berlin, Germany
- Africa Health Research Institute (AHRI), Durban, South Africa
- Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology and Harvard University, Cambridge, MA, United States
- Division of Infection and Immunity, University College London, London, United Kingdom
| | - Marcel Tongo
- Center of Research for Emerging and Re-Emerging Diseases (CREMER), Institute of Medical Research and Study of Medicinal Plants (IMPM), Yaoundé, Cameroon
| |
Collapse
|
2
|
Olety B, Usami Y, Wu Y, Peters P, Göttlinger H. AP-2 Adaptor Complex-Dependent Enhancement of HIV-1 Replication by Nef in the Absence of the Nef/AP-2 Targets SERINC5 and CD4. mBio 2023; 14:e0338222. [PMID: 36622146 PMCID: PMC9973267 DOI: 10.1128/mbio.03382-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 12/08/2022] [Indexed: 01/10/2023] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) Nef hijacks the clathrin adaptor complex 2 (AP-2) to downregulate the viral receptor CD4 and the antiviral multipass transmembrane proteins SERINC3 and SERINC5, which inhibit the infectivity of progeny virions when incorporated. In Jurkat Tag T lymphoid cells lacking SERINC3 and SERINC5, Nef is no longer required for full progeny virus infectivity and for efficient viral replication. However, in MOLT-3 T lymphoid cells, HIV-1 replication remains highly dependent on Nef even in the absence of SERINC3 and SERINC5. Using a knockout (KO) approach, we now show that the Nef-mediated enhancement of HIV-1 replication in MOLT-3 cells does not depend on the Nef-interacting kinases LCK and PAK2. Furthermore, Nef substantially enhanced HIV-1 replication even in triple-KO MOLT-3 cells that simultaneously lacked the three Nef/AP-2 targets, SERINC3, SERINC5, and CD4, and were reconstituted with a Nef-resistant CD4 to permit HIV-1 entry. Nevertheless, the ability of Nef mutants to promote HIV-1 replication in the triple-KO cells correlated strictly with the ability to bind AP-2. In addition, knockdown and reconstitution experiments confirmed the involvement of AP-2. These observations raise the possibility that MOLT-3 cells express a novel antiviral factor that is downregulated by Nef in an AP-2-dependent manner. IMPORTANCE The HIV-1 Nef protein hijacks a component of the cellular endocytic machinery called AP-2 to downregulate the viral receptor CD4 and the antiviral cellular membrane proteins SERINC3 and SERINC5. In the absence of Nef, SERINC3 and SERINC5 are taken up into viral particles, which reduces their infectivity. Surprisingly, in a T cell line called MOLT-3, Nef remains crucial for HIV-1 spreading in the absence of SERINC3 and SERINC5. We now show that this effect of Nef also does not depend on the cellular signaling molecules and Nef interaction partners LCK and PAK2. Nef was required for efficient HIV-1 spreading even in triple-knockout cells that completely lacked Nef/AP-2-sensitive CD4, in addition to the Nef/AP-2 targets SERINC3 and SERINC5. Nevertheless, our results indicate that the enhancement of HIV-1 spreading by Nef in the triple-knockout cells remained AP-2 dependent, which suggests the presence of an unknown antiviral factor that is sensitive to Nef/AP-2-mediated downregulation.
Collapse
Affiliation(s)
- Balaji Olety
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Yoshiko Usami
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Yuanfei Wu
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Paul Peters
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Heinrich Göttlinger
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| |
Collapse
|
3
|
Kandel SR, Luo X, He JJ. Nef inhibits HIV transcription and gene expression in astrocytes and HIV transmission from astrocytes to CD4 + T cells. J Neurovirol 2022; 28:552-565. [PMID: 36001227 DOI: 10.1007/s13365-022-01091-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 07/07/2022] [Accepted: 07/27/2022] [Indexed: 01/13/2023]
Abstract
HIV infects astrocytes in a restricted manner but leads to abundant expression of Nef, a major viral factor for HIV replication and disease progression. However, the roles of Nef in HIV gene expression and replication in astrocytes and viral transfer from astrocytes to CD4+ T cells remain largely unclear. In this study, we attempted to address these issues by transfecting human primary astrocytes with HIV molecular clones with intact Nef and without Nef (a nonsense Nef mutant) and comparing gene expression and replication in astrocytes and viral transfer from astrocytes to CD4+ T cells MT4. First, we found that lack of Nef expression led to increased extracellular virus production from astrocytes and intracellular viral protein and RNA expression in astrocytes. Using a HIV LTR-driven luciferase reporter gene assay, we showed that ectopic Nef expression alone inhibited the HIV LTR promoter activity in astrocytes. Consistent with the previously established function of Nef, we showed that the infectivity of HIV derived from astrocytes with Nef expression was significantly higher than that with no Nef expression. Next, we performed the co-culture assay to determine HIV transfer from astrocytes transfected to MT4. We showed that lack of Nef expression led to significant increase in HIV transfer from astrocytes to MT4 using two HIV clones. We also used Nef-null HIV complemented with Nef in trans in the co-culture assay and demonstrated that Nef expression led to significantly decreased HIV transfer from astrocytes to MT4. Taken together, these findings support a negative role of Nef in HIV replication and pathogenesis in astrocytes.
Collapse
Affiliation(s)
- Suresh R Kandel
- Department of Microbiology and Immunology, Chicago Medical School, Rosalind Franklin University, North Chicago, IL, 60064, USA.,Center for Cancer Cell Biology, Immunology and Infection, Rosalind Franklin University, North Chicago, IL, 60064, USA.,School of Graduate and Postdoctoral Studies, Rosalind Franklin University, 3333 Green Bay Road, North Chicago, IL, 60064, USA
| | - Xiaoyu Luo
- Gladstone Institute of Virology, University of California at San Francisco, San Francisco, CA, 94158, USA
| | - Johnny J He
- Department of Microbiology and Immunology, Chicago Medical School, Rosalind Franklin University, North Chicago, IL, 60064, USA. .,Center for Cancer Cell Biology, Immunology and Infection, Rosalind Franklin University, North Chicago, IL, 60064, USA. .,School of Graduate and Postdoctoral Studies, Rosalind Franklin University, 3333 Green Bay Road, North Chicago, IL, 60064, USA.
| |
Collapse
|
4
|
McNamara RP, Dittmer DP. Extracellular vesicles in virus infection and pathogenesis. Curr Opin Virol 2020; 44:129-138. [PMID: 32846272 PMCID: PMC7755726 DOI: 10.1016/j.coviro.2020.07.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 07/18/2020] [Accepted: 07/20/2020] [Indexed: 12/11/2022]
Abstract
Viruses are obligate intracellular parasites that usurp cellular signaling networks to promote pathogen spread and disease progression. Signaling through extracellular vesicles (EVs) is an emerging field of study in the virus-host interaction network. EVs relay information both locally and distally through incorporated contents, typically without tripping innate immune sensors. Therefore, this extracellular signaling axis presents itself as a tantalizing target for promoting a favorable niche for the pathogen(s) takeover of the host, particularly for chronic infections. From the incorporation of virus-encoded molecules such as micro RNAs and proteins/enzymes to the envelopment of entire infectious particles, evolutionary distinct viruses have shown a remarkable ability to converge on this means of communication. In this review, we will cover the recent advances in this field and explore how EV can be used as potential biomarkers for chronic, persistent, or latent virus infections.
Collapse
Affiliation(s)
- Ryan P McNamara
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, United States; Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, United States
| | - Dirk P Dittmer
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, United States; Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, United States.
| |
Collapse
|
5
|
Proulx J, Borgmann K, Park IW. Post-translational modifications inducing proteasomal degradation to counter HIV-1 infection. Virus Res 2020; 289:198142. [PMID: 32882242 DOI: 10.1016/j.virusres.2020.198142] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 08/20/2020] [Accepted: 08/21/2020] [Indexed: 12/14/2022]
Abstract
Post-translational modifications (PTMs) are integral to regulating a wide variety of cellular processes in eukaryotic cells, such as regulation of protein stability, alteration of celluar location, protein activity modulation, and regulation of protein interactions. HIV-1, like other eukaryotic viruses, and its infected host exploit the proteasomal degradation system for their respective proliferation and survival, using various PTMs, including but not limited to ubiquitination, SUMOylation, NEDDylation, interferon-stimulated gene (ISG)ylation. Essentially all viral proteins within the virions -- and in the HIV-1-infected cells -- interact with their cellular counterparts for this degradation, utilizing ubiquitin (Ub), and the Ub-like (Ubl) modifiers less frequently, to eliminate the involved proteins throughout the virus life cycle, from the entry step to release of the assembled virus particles. Such interplay is pivotal for, on the one hand, the cell to restrict proliferation of the infecting virus, and on the other, for molecular counteraction by the virus to overcome this cellular protein-imposed restriction. Recent reports indicate that not only viral/cellular proteins but also viral/viral protein interactions play vital roles in regulating viral protein stability. We hence give an overview of the molecular processes of PTMs involved in proteasomal degradation of the viral and cellular proteins, and the viral/viral and viral/cellular protein interplay in restriction and competition for HIV-1 vs. host cell survival. Insights in this realm could open new avenues for developing therapeutics against HIV-1 via targeting specific steps of the proteasome degradation pathway during the HIV-1 life cycle.
Collapse
Affiliation(s)
- Jessica Proulx
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, 76107, United States
| | - Kathleen Borgmann
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, 76107, United States
| | - In-Woo Park
- Microbiology, Immunology, and Genetics, University of North Texas Health Science Center, Fort Worth, TX, 76107, United States.
| |
Collapse
|
6
|
Stoneham CA, Ramirez PW, Singh R, Suarez M, Debray A, Lim C, Jia X, Xiong Y, Guatelli J. A Conserved Acidic-Cluster Motif in SERINC5 Confers Partial Resistance to Antagonism by HIV-1 Nef. J Virol 2020; 94:e01554-19. [PMID: 31941773 PMCID: PMC7081897 DOI: 10.1128/jvi.01554-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 01/12/2020] [Indexed: 12/15/2022] Open
Abstract
The cellular protein SERINC5 inhibits the infectivity of diverse retroviruses, and its activity is counteracted by the glycosylated Gag (glycoGag) protein of murine leukemia virus (MLV), the S2 protein of equine infectious anemia virus (EIAV), and the Nef protein of human immunodeficiency virus type 1 (HIV-1). Determining the regions within SERINC5 that provide restrictive activity or Nef sensitivity should inform mechanistic models of the SERINC5/HIV-1 relationship. Here, we report that deletion of the conserved sequence EDTEE, which is located within a cytoplasmic loop of SERINC5 and which is reminiscent of an acidic-cluster membrane trafficking signal, increases the sensitivity of SERINC5 to antagonism by Nef, while it has no effect on the intrinsic activity of the protein as an inhibitor of infectivity. These effects correlated with enhanced removal of the ΔEDTEE mutant relative to that of wild-type SERINC5 from the cell surface and with enhanced exclusion of the mutant protein from virions by Nef. Mutational analysis indicated that the acidic residues, but not the threonine, within the EDTEE motif are important for the relative resistance to Nef. Deletion of the EDTEE sequence did not increase the sensitivity of SERINC5 to antagonism by the glycoGag protein of MLV, suggesting that its virologic role is Nef specific. These results are consistent with the reported mapping of the cytoplasmic loop that contains the EDTEE sequence as a general determinant of Nef responsiveness, but they further indicate that sequences inhibitory to as well as supportive of Nef activity reside in this region. We speculate that the EDTEE motif might have evolved to mediate resistance against retroviruses that use Nef-like proteins to antagonize SERINC5.IMPORTANCE Cellular membrane proteins in the SERINC family, especially SERINC5, inhibit the infectivity of retroviral virions. This inhibition is counteracted by retroviral proteins, specifically, HIV-1 Nef, MLV glycoGag, and EIAV S2. One consequence of such a host-pathogen "arms race" is a compensatory change in the host antiviral protein as it evolves to escape the effects of viral antagonists. This is often reflected in a genetic signature, positive selection, which is conspicuously missing in SERINC5 Here we show that despite this lack of genetic evidence, a sequence in SERINC5 nonetheless provides relative resistance to antagonism by HIV-1 Nef.
Collapse
Affiliation(s)
- Charlotte A Stoneham
- Department of Medicine, University of California San Diego, La Jolla, California, USA
- The VA San Diego Healthcare System, San Diego, California, USA
| | - Peter W Ramirez
- Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Rajendra Singh
- Department of Medicine, University of California San Diego, La Jolla, California, USA
- The VA San Diego Healthcare System, San Diego, California, USA
| | - Marissa Suarez
- The VA San Diego Healthcare System, San Diego, California, USA
| | - Andrew Debray
- Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Christopher Lim
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - Xiaofei Jia
- Department of Chemistry and Biochemistry, University of Massachusetts Dartmouth, Dartmouth, Massachusetts, USA
| | - Yong Xiong
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - John Guatelli
- Department of Medicine, University of California San Diego, La Jolla, California, USA
- The VA San Diego Healthcare System, San Diego, California, USA
| |
Collapse
|
7
|
Pyeon D, Rojas VK, Price L, Kim S, Singh M, Park IW. HIV-1 Impairment via UBE3A and HIV-1 Nef Interactions Utilizing the Ubiquitin Proteasome System. Viruses 2019; 11:v11121098. [PMID: 31783587 PMCID: PMC6950590 DOI: 10.3390/v11121098] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 11/15/2019] [Accepted: 11/25/2019] [Indexed: 12/30/2022] Open
Abstract
Molecular basis of HIV-1 life cycle regulation has thus far focused on viral gene stage-specificity, despite the quintessence of post-function protein elimination processes in the virus life cycle and consequent pathogenesis. Our studies demonstrated that a key pathogenic HIV-1 viral protein, Nef, interacted with ubiquitin (Ub)-protein ligase E3A (UBE3A/E6AP), suggesting that interaction between Nef and UBE3A is integral to regulation of viral and cellular protein decay and thereby the competing HIV-1 and host cell survivals. In fact, Nef and UBE3A degraded reciprocally, and UBE3A-mediated degradation of Nef was significantly more potent than Nef-triggered degradation of UBE3A. Further, UBE3A degraded not only Nef but also HIV-1 structural proteins, Gag, thus significantly inhibiting HIV-1 replication in Jurkat T cells only in the presence of Nef, indicating that interaction between Nef and UBE3Awas pivotal for UBE3A-mediated degradation of the viral proteins. Mechanistic study showed that Nef and UBE3A were specific and antagonistic to each other in regulating proteasome activity and ubiquitination of cellular proteins in general, wherein specific domains of Nef overlapping with the long terminal repeat (LTR) were essential for the observed actions. Further, Nef itself reduced the level of intracellular Gag by degrading a cardinal transcription regulator, Tat, demonstrating a broad role for Nef in the regulation of the HIV-1 life cycle. Taken together, these data demonstrated that the Nef and UBE3A complex plays a crucial role in coordinating viral protein degradation and hence HIV-1 replication, providing insights as to the nature of pathobiologic and defense strategies of HIV-1 and HIV-infected host cells.
Collapse
Affiliation(s)
- Dohun Pyeon
- Departments of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA;
| | - Vivian K. Rojas
- Department of Microbiology, Immunology and Genetics, University of North Texas Health Science Center, Fort Worth, TX 76107, USA; (V.K.R.); (L.P.)
| | - Lenore Price
- Department of Microbiology, Immunology and Genetics, University of North Texas Health Science Center, Fort Worth, TX 76107, USA; (V.K.R.); (L.P.)
| | - Seongcheol Kim
- Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, USA (M.S.)
| | - Meharvan Singh
- Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, USA (M.S.)
| | - In-Woo Park
- Department of Microbiology, Immunology and Genetics, University of North Texas Health Science Center, Fort Worth, TX 76107, USA; (V.K.R.); (L.P.)
- Correspondence: ; Tel.: +(817)-735-5115; Fax: +(817)-735-2610
| |
Collapse
|
8
|
Rojas VK, Park IW. Role of the Ubiquitin Proteasome System (UPS) in the HIV-1 Life Cycle. Int J Mol Sci 2019; 20:ijms20122984. [PMID: 31248071 PMCID: PMC6628307 DOI: 10.3390/ijms20122984] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 06/10/2019] [Accepted: 06/11/2019] [Indexed: 01/18/2023] Open
Abstract
Given that the ubiquitin proteasome system (UPS) is the major protein degradation process in the regulation of a wide variety of cellular processes in eukaryotic cells, including alteration of cellular location, modulation of protein activity, and regulation of protein interaction, it is reasonable to suggest that the infecting HIV-1 and the invaded hosts exploit the UPS in a contest for survival and proliferation. However, to date, regulation of the HIV-1 life cycle has been mainly explained by the stage-specific expression of HIV-1 viral genes, not by elimination processes of the synthesized proteins after completion of their duties in the infected cells, which is also quintessential for understanding the molecular processes of the virus life cycle and thereby HIV-1 pathogenesis. In fact, several previous publications have indicated that the UPS plays a critical role in the regulation of the proteasomal degradation of viral and cellular counterparts at every step of the HIV-1 life cycle, from the virus entry to release of the assembled virus particles, which is integral for the regulation of survival and proliferation of the infecting HIV-1 and to replication restriction of the invading virus in the host. However, it is unknown whether and how these individual events taking place at different stages of the HIV-1 life cycle are orchestrated as an overall strategy to overcome the restrictions conferred by the host cells. Thus, in this review, we overview the interplay between HIV-1 viral and cellular proteins for restrictions/competitions for proliferation of the virus in the infected cell, which could open a new avenue for the development of therapeutics against HIV-1 via targeting a specific step of the proteasome degradation pathway during the HIV-1 life cycle.
Collapse
Affiliation(s)
- Vivian K Rojas
- Department of Microbiology, Immunology, and Genetics, University of North Texas, Health Science Center, Fort Worth, TX 76107, USA.
| | - In-Woo Park
- Department of Microbiology, Immunology, and Genetics, University of North Texas, Health Science Center, Fort Worth, TX 76107, USA.
| |
Collapse
|
9
|
Abstract
The Nef protein of HIV-1 and the unrelated glycoGag protein of a murine leukemia virus similarly prevent the uptake of antiviral host proteins called SERINC3 and SERINC5 into HIV-1 particles, which enhances their infectiousness. We now show that although both SERINC antagonists can in principle similarly enhance HIV-1 replication, glycoGag is unable to substitute for Nef in primary human cells and in a T cell line called MOLT-3. In MOLT-3 cells, Nef remained crucial for HIV-1 replication even in the absence of SERINC3 and SERINC5. The pronounced effect of Nef on HIV-1 spreading in MOLT-3 cells correlated with the ability of Nef to engage cellular endocytic machinery and to downregulate the HIV-1 receptor CD4 but nevertheless persisted in the absence of CD4 downregulation. Collectively, our results provide evidence for a potent novel restriction activity that affects even relatively SERINC-resistant HIV-1 isolates and is counteracted by Nef. It has recently emerged that HIV-1 Nef counteracts the antiviral host proteins SERINC3 and SERINC5. In particular, SERINC5 inhibits the infectivity of progeny virions when incorporated. SERINC3 and SERINC5 are also counteracted by the unrelated murine leukemia virus glycosylated Gag (glycoGag) protein, which possesses a potent Nef-like activity on HIV-1 infectivity. We now report that a minimal glycoGag termed glycoMA can fully substitute for Nef in promoting HIV-1 replication in Jurkat T lymphoid cells, indicating that Nef enhances replication in these cells mainly by counteracting SERINCs. In contrast, the SERINC antagonist glycoMA was unable to substitute for Nef in MOLT-3 T lymphoid cells, in which HIV-1 replication was highly dependent on Nef, and remained so even in the absence of SERINC3 and SERINC5. As in MOLT-3 cells, glycoMA was unable to substitute for Nef in stimulating HIV-1 replication in primary human cells. Although the ability of Nef mutants to promote HIV-1 replication in MOLT-3 cells correlated with the ability to engage endocytic machinery and to downregulate CD4, Nef nevertheless rescued virus replication under conditions where CD4 downregulation did not occur. Taken together, our observations raise the possibility that Nef triggers the endocytosis of a novel antiviral factor that is active against both laboratory-adapted and primary HIV-1 strains.
Collapse
|
10
|
McNamara RP, Costantini LM, Myers TA, Schouest B, Maness NJ, Griffith JD, Damania BA, MacLean AG, Dittmer DP. Nef Secretion into Extracellular Vesicles or Exosomes Is Conserved across Human and Simian Immunodeficiency Viruses. mBio 2018; 9:e02344-17. [PMID: 29437924 PMCID: PMC5801467 DOI: 10.1128/mbio.02344-17] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 01/10/2018] [Indexed: 02/07/2023] Open
Abstract
Extracellular vesicles (EVs) or exosomes have been implicated in the pathophysiology of infections and cancer. The negative regulatory factor (Nef) encoded by simian immunodeficiency virus (SIV) and human immunodeficiency virus (HIV) plays a critical role in the progression to AIDS and impairs endosomal trafficking. Whether HIV-1 Nef can be loaded into EVs has been the subject of controversy, and nothing is known about the connection between SIV Nef and EVs. We find that both SIV and HIV-1 Nef proteins are present in affinity-purified EVs derived from cultured cells, as well as in EVs from SIV-infected macaques. Nef-positive EVs were functional, i.e., capable of membrane fusion and depositing their content into recipient cells. The EVs were able to transfer Nef into recipient cells. This suggests that Nef readily enters the exosome biogenesis pathway, whereas HIV virions are assembled at the plasma membrane. It suggests a novel mechanism by which lentiviruses can influence uninfected and uninfectable, i.e., CD4-negative, cells.IMPORTANCE Extracellular vesicles (EVs) transfer biologically active materials from one cell to another, either within the adjacent microenvironment or further removed. EVs also package viral RNAs, microRNAs, and proteins, which contributes to the pathophysiology of infection. In this report, we show that both human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) incorporate the virus-encoded Nef protein into EVs, including EVs circulating in the blood of SIV-infected macaques and that this presents a novel mechanism of Nef transfer to naive and even otherwise non-infectable cells. Nef is dispensable for viral replication but essential for AIDS progression in vivo Demonstrating that Nef incorporation into EVs is conserved across species implicates EVs as novel mediators of the pathophysiology of HIV. It could help explain the biological effects that HIV has on CD4-negative cells and EVs could become biomarkers of disease progression.
Collapse
Affiliation(s)
- Ryan P McNamara
- Department of Microbiology and Immunology, Lineberger Comprehensive Cancer Center, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Lindsey M Costantini
- Department of Microbiology and Immunology, Lineberger Comprehensive Cancer Center, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - T Alix Myers
- Tulane National Primate Research Center, Tulane University, Covington, Louisiana, USA
| | - Blake Schouest
- Tulane National Primate Research Center, Tulane University, Covington, Louisiana, USA
| | - Nicholas J Maness
- Tulane National Primate Research Center, Tulane University, Covington, Louisiana, USA
| | - Jack D Griffith
- Department of Microbiology and Immunology, Lineberger Comprehensive Cancer Center, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Blossom A Damania
- Department of Microbiology and Immunology, Lineberger Comprehensive Cancer Center, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Andrew G MacLean
- Tulane National Primate Research Center, Tulane University, Covington, Louisiana, USA
| | - Dirk P Dittmer
- Department of Microbiology and Immunology, Lineberger Comprehensive Cancer Center, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| |
Collapse
|
11
|
Qin J, Lu C. Infection of KSHV and Interaction with HIV: The Bad Romance. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1018:237-251. [PMID: 29052142 DOI: 10.1007/978-981-10-5765-6_15] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV), namely, human herpesvirus 8 (HHV-8), is considered as the pathogen of Kaposi's sarcoma (KS), the most frequent cancer in untreated HIV-infected individuals. Patients infected with HIV have a much higher possibility developing KS than average individual. Researchers have found that HIV, which functions as a cofactor of KS, contributes a lot to the development of KS. In this article, we will give a brief introduction of KS and KSHV and how the interaction between KSHV and HIV contributes to the development of KS. Also we will take a glance at the development of treatment in KS, especially AIDS-KS.
Collapse
Affiliation(s)
- Jie Qin
- Key Laboratory of Pathogen Biology (Jiangsu Province), Nanjing Medical University, Nanjing, People's Republic of China.,Department of Microbiology, Nanjing Medical University, Nanjing, 210029, People's Republic of China
| | - Chun Lu
- Key Laboratory of Pathogen Biology (Jiangsu Province), Nanjing Medical University, Nanjing, People's Republic of China. .,Department of Microbiology, Nanjing Medical University, Nanjing, 210029, People's Republic of China.
| |
Collapse
|
12
|
Sabino Cunha M, Lima Sampaio T, Peterlin BM, Jesus da Costa L. A Truncated Nef Peptide from SIVcpz Inhibits the Production of HIV-1 Infectious Progeny. Viruses 2016; 8:v8070189. [PMID: 27399760 PMCID: PMC4974524 DOI: 10.3390/v8070189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 06/08/2016] [Accepted: 06/14/2016] [Indexed: 12/02/2022] Open
Abstract
Nef proteins from all primate Lentiviruses, including the simian immunodeficiency virus of chimpanzees (SIVcpz), increase viral progeny infectivity. However, the function of Nef involved with the increase in viral infectivity is still not completely understood. Nonetheless, until now, studies investigating the functions of Nef from SIVcpz have been conducted in the context of the HIV-1 proviruses. In an attempt to investigate the role played by Nef during the replication cycle of an SIVcpz, a Nef-defective derivative was obtained from the SIVcpzWTGab2 clone by introducing a frame shift mutation at a unique restriction site within the nef sequence. This nef-deleted clone expresses an N-terminal 74-amino acid truncated peptide of Nef and was named SIVcpz-tNef. We found that the SIVcpz-tNef does not behave as a classic nef-deleted HIV-1 or simian immunodeficiency virus of macaques SIVmac. Markedly, SIVcpz-tNef progeny from both Hek-293T and Molt producer cells were completely non-infectious. Moreover, the loss in infectivity of SIVcpz-tNef correlated with the inhibition of Gag and GagPol processing. A marked accumulation of Gag and very low levels of reverse transcriptase were detected in viral lysates. Furthermore, these observations were reproduced once the tNef peptide was expressed in trans both in SIVcpzΔNef and HIV-1WT expressing cells, demonstrating that the truncated peptide is a dominant negative for viral processing and infectivity for both SIVcpz and HIV-1. We demonstrated that the truncated Nef peptide binds to GagPol outside the protease region and by doing so probably blocks processing of both GagPol and Gag precursors at a very early stage. This study demonstrates for the first time that naturally-occurring Nef peptides can potently block lentiviral processing and infectivity.
Collapse
Affiliation(s)
- Marcela Sabino Cunha
- Departamento de Virologia-Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho 373-CCS-Bloco I, Rio de Janeiro 21941-902, Brazil.
| | - Thatiane Lima Sampaio
- Departamento de Virologia-Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho 373-CCS-Bloco I, Rio de Janeiro 21941-902, Brazil.
| | - B Matija Peterlin
- Departments of Medicine, Microbiology and Immunology, University of California, San Francisco, 533 Parnassus Avenue, San Francisco, CA 94143, USA.
| | - Luciana Jesus da Costa
- Departamento de Virologia-Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho 373-CCS-Bloco I, Rio de Janeiro 21941-902, Brazil.
| |
Collapse
|
13
|
Usami Y, Wu Y, Göttlinger HG. SERINC3 and SERINC5 restrict HIV-1 infectivity and are counteracted by Nef. Nature 2015; 526:218-23. [PMID: 26416733 PMCID: PMC4600458 DOI: 10.1038/nature15400] [Citation(s) in RCA: 323] [Impact Index Per Article: 35.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 08/18/2015] [Indexed: 12/13/2022]
Abstract
HIV-1 Nef and the unrelated murine leukemia virus glycoGag strongly enhance the infectivity of HIV-1 virions produced in certain cell types in a clathrin-dependent manner. Here we show that Nef and glycoGag prevent the incorporation of the multipass transmembrane proteins SERINC3 and SERINC5 into HIV-1 virions to an extent that correlates with infectivity enhancement. Silencing of SERINC3 together with SERINC5 precisely phenocopied the effects of Nef and glycoGag on HIV-1 infectivities. The infectivity of nef-deficient virions increased more than 100-fold when produced in double-knockout human CD4+ T cells that lack both SERINC3 and SERINC5, and re-expression experiments confirmed that the absence of SERINC3 and SERINC5 accounted for the infectivity enhancement. Furthermore, SERINC3 and SERINC5 together restricted HIV-1 replication, and this restriction was evaded by Nef. SERINC3 and SERINC5 are highly expressed in primary human HIV-1 target cells, and inhibiting their downregulation by Nef is a potential strategy to combat HIV/AIDS.
Collapse
Affiliation(s)
- Yoshiko Usami
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Yuanfei Wu
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Heinrich G Göttlinger
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| |
Collapse
|
14
|
Bose D, Gagnon J, Chebloune Y. Comparative Analysis of Tat-Dependent and Tat-Deficient Natural Lentiviruses. Vet Sci 2015; 2:293-348. [PMID: 29061947 PMCID: PMC5644649 DOI: 10.3390/vetsci2040293] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 08/24/2015] [Accepted: 08/24/2015] [Indexed: 01/10/2023] Open
Abstract
The emergence of human immunodeficiency virus (HIV) causing acquired immunodeficiency syndrome (AIDS) in infected humans has resulted in a global pandemic that has killed millions. HIV-1 and HIV-2 belong to the lentivirus genus of the Retroviridae family. This genus also includes viruses that infect other vertebrate animals, among them caprine arthritis-encephalitis virus (CAEV) and Maedi-Visna virus (MVV), the prototypes of a heterogeneous group of viruses known as small ruminant lentiviruses (SRLVs), affecting both goat and sheep worldwide. Despite their long host-SRLV natural history, SRLVs were never found to be responsible for immunodeficiency in contrast to primate lentiviruses. SRLVs only replicate productively in monocytes/macrophages in infected animals but not in CD4+ T cells. The focus of this review is to examine and compare the biological and pathological properties of SRLVs as prototypic Tat-independent lentiviruses with HIV-1 as prototypic Tat-dependent lentiviruses. Results from this analysis will help to improve the understanding of why and how these two prototypic lentiviruses evolved in opposite directions in term of virulence and pathogenicity. Results may also help develop new strategies based on the attenuation of SRLVs to control the highly pathogenic HIV-1 in humans.
Collapse
Affiliation(s)
- Deepanwita Bose
- Pathogénèse et Vaccination Lentivirales, PAVAL Lab., Université Joseph Fourier Grenoble 1, Bat. NanoBio2, 570 rue de la Chimie, BP 53, 38041, Grenoble Cedex 9, France.
| | - Jean Gagnon
- Pathogénèse et Vaccination Lentivirales, PAVAL Lab., Université Joseph Fourier Grenoble 1, Bat. NanoBio2, 570 rue de la Chimie, BP 53, 38041, Grenoble Cedex 9, France.
| | - Yahia Chebloune
- Pathogénèse et Vaccination Lentivirales, PAVAL Lab., Université Joseph Fourier Grenoble 1, Bat. NanoBio2, 570 rue de la Chimie, BP 53, 38041, Grenoble Cedex 9, France.
| |
Collapse
|
15
|
Basmaciogullari S, Pizzato M. The activity of Nef on HIV-1 infectivity. Front Microbiol 2014; 5:232. [PMID: 24904546 PMCID: PMC4033043 DOI: 10.3389/fmicb.2014.00232] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 04/30/2014] [Indexed: 12/29/2022] Open
Abstract
The replication and pathogenicity of lentiviruses is crucially modulated by “auxiliary proteins” which are expressed in addition to the canonical retroviral ORFs gag, pol, and env. Strategies to inhibit the activity of such proteins are often sought and proposed as possible additions to increase efficacy of the traditional antiretroviral therapy. This requires the acquisition of an in-depth knowledge of the molecular mechanisms underlying their function. The Nef auxiliary protein is expressed uniquely by primate lentiviruses and plays an important role in virus replication in vivo and in the onset of AIDS. Among its several activities Nef enhances the intrinsic infectivity of progeny virions through a mechanism which remains today enigmatic. Here we review the current knowledge surrounding such activity and we discuss its possible role in HIV biology.
Collapse
Affiliation(s)
- Stéphane Basmaciogullari
- Hôpital Necker-Enfants Malades, Sorbonne Paris Cité, Université Paris Descartes Paris, France ; INSERM U845 Paris, France
| | - Massimo Pizzato
- Centre for Integrative Biology, University of Trento Trento, Italy
| |
Collapse
|
16
|
The link between CD8⁺ T-cell antigen-sensitivity and HIV-suppressive capacity depends on HLA restriction, target epitope and viral isolate. AIDS 2014; 28:477-86. [PMID: 24384691 DOI: 10.1097/qad.0000000000000175] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND Although it is established that CD8 T-cell immunity is critical for the control of HIV replication in vivo, the key factors that determine antiviral efficacy are yet to be fully elucidated. Antigen-sensitivity and T-cell receptor (TCR) avidity have been identified as potential determinants of CD8⁺ T-cell efficacy. However, there is no general consensus in this regard because the relationship between these parameters and the control of HIV infection has been established primarily in the context of immunodominant CD8⁺ T-cell responses against the Gag₂₆₃₋₂₇₂ KK10 epitope restricted by human leukocyte antigen (HLA)-B27. METHODS To investigate the relationship between antigen-sensitivity, TCR avidity and HIV-suppressive capacity in vitro across epitope specificities and HLA class I restriction elements, we used a variety of techniques to study CD8⁺ T-cell clones specific for Nef₇₃₋₈₂ QK10 and Gag₂₀₋₂₉ RY10, both restricted by HLA-A3, alongside CD8⁺ T-cell clones specific for Gag₂₆₃₋₂₇₂ KK10. RESULTS For each targeted epitope, the linked parameters of antigen-sensitivity and TCR avidity correlated directly with antiviral efficacy. However, marked differences in HIV-suppressive capacity were observed between epitope specificities, HLA class I restriction elements and viral isolates. CONCLUSIONS Collectively, these data emphasize the central role of the TCR as a determinant of CD8⁺ T-cell efficacy and demonstrate that the complexities of antigen recognition across epitope and HLA class I boundaries can confound simple relationships between TCR engagement and HIV suppression.
Collapse
|
17
|
Weiser K, Barton M, Gershoony D, DasGupta R, Cardozo T. HIV's Nef interacts with β-catenin of the Wnt signaling pathway in HEK293 cells. PLoS One 2013; 8:e77865. [PMID: 24130899 PMCID: PMC3795062 DOI: 10.1371/journal.pone.0077865] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Accepted: 09/13/2013] [Indexed: 11/18/2022] Open
Abstract
The Wnt signaling pathway is implicated in major physiologic cellular functions, such as proliferation, migration, cell fate specification, maintenance of pluripotency and induction of tumorigenicity. Proliferation and migration are important responses of T-cells, which are major cellular targets of HIV infection. Using an informatics screen, we identified a previously unsuspected interaction between HIV’s Nef protein and β-catenin, a key component of the Wnt pathway. A segment in Nef contains identical amino acids at key positions and structurally mimics the β-catenin binding sites on endogenous β-catenin ligands. The interaction between Nef and β-catenin was confirmed in vitro and in a co-immunoprecipitation from HEK293 cells. Moreover, the introduction of Nef into HEK293 cells specifically inhibited a Wnt pathway reporter.
Collapse
Affiliation(s)
- Keren Weiser
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York, United States of America
| | - Meredith Barton
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York, United States of America
| | - Dafna Gershoony
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York, United States of America
| | - Ramanuj DasGupta
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York, United States of America
| | - Timothy Cardozo
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York, United States of America
- * E-mail:
| |
Collapse
|
18
|
Malbec M, Sourisseau M, Guivel-Benhassine F, Porrot F, Blanchet F, Schwartz O, Casartelli N. HIV-1 Nef promotes the localization of Gag to the cell membrane and facilitates viral cell-to-cell transfer. Retrovirology 2013; 10:80. [PMID: 23899341 PMCID: PMC3734038 DOI: 10.1186/1742-4690-10-80] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 07/26/2013] [Indexed: 11/16/2022] Open
Abstract
Background Newly synthesized HIV-1 particles assemble at the plasma membrane of infected cells, before being released as free virions or being transferred through direct cell-to-cell contacts to neighboring cells. Localization of HIV-1 Gag precursor at the cell membrane is necessary and sufficient to trigger viral assembly, whereas the GagPol precursor is additionally required to generate a fully matured virion. HIV-1 Nef is an accessory protein that optimizes viral replication through partly defined mechanisms. Whether Nef modulates Gag and/or GagPol localization and assembly at the membrane and facilitates viral cell-to-cell transfer has not been extensively characterized so far. Results We report that Nef increases the total amount of Gag proteins present in infected cells, and promotes Gag localization at the cell membrane. Moreover, the processing of p55 into p24 is improved in the presence of Nef. We also examined the effect of Nef during HIV-1 cell-to-cell transfer. We show that without Nef, viral transfer through direct contacts between infected cells and target cells is impaired. With a nef-deleted virus, the number of HIV-1 positive target cells after a short 2h co-culture is reduced, and viral material transferred to uninfected cells is less matured. At later time points, this defect is associated with a reduction in the productive infection of new target cells. Conclusions Our results highlight a previously unappreciated role of Nef during the viral replication cycle. Nef promotes HIV-1 Gag membrane localization and processing, and facilitates viral cell-to-cell transfer.
Collapse
Affiliation(s)
- Marine Malbec
- Département de Virologie, Institut Pasteur, Unité Virus et Immunité, 28 rue du Docteur Roux, Paris F-75015, France
| | | | | | | | | | | | | |
Collapse
|
19
|
Cruz NVG, Amorim R, Oliveira FE, Speranza FAC, Costa LJ. Mutations in the nef and vif genes associated with progression to AIDS in elite controller and slow-progressor patients. J Med Virol 2013; 85:563-74. [PMID: 23417613 DOI: 10.1002/jmv.23512] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2012] [Indexed: 11/07/2022]
Abstract
Progression towards AIDS can vary from 5 to 10 years from the establishment of the primary infection by HIV-1 to more than 10 years in the complete absence of antiretroviral therapy. Several factors can contribute to the outcome of HIV infection, including host genetic and viral replicating characteristics. Historically, nef-deleted viral genomes have been associated with disease progression. Therefore, the lentiviral Nef protein is regarded as a progression factor. The objective of this work was to characterize the nef gene from a group of treatment naive patients infected with HIV-1 for more than 10 years. These patients were classified as long-term non-progressors, elite controller, and slow-progressors according to clinical and laboratorial data. A premature stop codon within the nef gene leading to the expression of a truncated peptide was observed on samples from the elite controller patient. For the slow-progressor patients, several degrees of deletions at the C-terminal of Nef were observed predicting a loss of function of this protein. The vif gene was characterized for these patients and a rare mutation that predicts a miss localization of the Vif protein to the nucleus of infected cells that could prevent its function as an APOBEC neutralization factor was also observed. These data indicate the importance of the HIV accessory proteins as factors that contribute to the outcome of AIDS.
Collapse
Affiliation(s)
- Nadia V G Cruz
- Department of Virology, Institute of Microbiology Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | | | | | | | | |
Collapse
|
20
|
Meuwissen PJ, Stolp B, Iannucci V, Vermeire J, Naessens E, Saksela K, Geyer M, Vanham G, Arien KK, Fackler OT, Verhasselt B. Identification of a highly conserved valine-glycine-phenylalanine amino acid triplet required for HIV-1 Nef function. Retrovirology 2012; 9:34. [PMID: 22537596 PMCID: PMC3476393 DOI: 10.1186/1742-4690-9-34] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Accepted: 04/27/2012] [Indexed: 12/02/2022] Open
Abstract
Background The Nef protein of HIV facilitates virus replication and disease progression in infected patients. This role as pathogenesis factor depends on several genetically separable Nef functions that are mediated by interactions of highly conserved protein-protein interaction motifs with different host cell proteins. By studying the functionality of a series of nef alleles from clinical isolates, we identified a dysfunctional HIV group O Nef in which a highly conserved valine-glycine-phenylalanine (VGF) region, which links a preceding acidic cluster with the following proline-rich motif into an amphipathic surface was deleted. In this study, we aimed to study the functional importance of this VGF region. Results The dysfunctional HIV group O8 nef allele was restored to the consensus sequence, and mutants of canonical (NL4.3, NA-7, SF2) and non-canonical (B2 and C1422) HIV-1 group M nef alleles were generated in which the amino acids of the VGF region were changed into alanines (VGF→AAA) and tested for their capacity to interfere with surface receptor trafficking, signal transduction and enhancement of viral replication and infectivity. We found the VGF motif, and each individual amino acid of this motif, to be critical for downregulation of MHC-I and CXCR4. Moreover, Nef’s association with the cellular p21-activated kinase 2 (PAK2), the resulting deregulation of cofilin and inhibition of host cell actin remodeling, and targeting of Lck kinase to the trans-golgi-network (TGN) were affected as well. Of particular interest, VGF integrity was essential for Nef-mediated enhancement of HIV virion infectivity and HIV replication in peripheral blood lymphocytes. For targeting of Lck kinase to the TGN and viral infectivity, especially the phenylalanine of the triplet was essential. At the molecular level, the VGF motif was required for the physical interaction of the adjacent proline-rich motif with Hck. Conclusion Based on these findings, we propose that this highly conserved three amino acid VGF motif together with the acidic cluster and the proline-rich motif form a previously unrecognized amphipathic surface on Nef. This surface appears to be essential for the majority of Nef functions and thus represents a prime target for the pharmacological inhibition of Nef.
Collapse
Affiliation(s)
- Pieter J Meuwissen
- Department of Clinical Chemistry, Microbiology, and Immunology, Ghent University, Ghent, (B-9000), Belgium
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
21
|
Vermeire J, Vanbillemont G, Witkowski W, Verhasselt B. The Nef-infectivity enigma: mechanisms of enhanced lentiviral infection. Curr HIV Res 2012; 9:474-89. [PMID: 22103831 PMCID: PMC3355465 DOI: 10.2174/157016211798842099] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Revised: 10/24/2011] [Accepted: 10/27/2011] [Indexed: 11/22/2022]
Abstract
The Nef protein is an essential factor for lentiviral pathogenesis in humans and other simians. Despite a multitude of functions attributed to this protein, the exact role of Nef in disease progression remains unclear. One of its most intriguing functions is the ability of Nef to enhance the infectivity of viral particles. In this review we will discuss current insights in the mechanism of this well-known, yet poorly understood Nef effect. We will elaborate on effects of Nef, on both virion biogenesis and the early stage of the cellular infection, that might be involved in infectivity enhancement. In addition, we provide an overview of different HIV-1 Nef domains important for optimal infectivity and briefly discuss some possible sources of the frequent discrepancies in the field. Hereby we aim to contribute to a better understanding of this highly conserved and therapeutically attractive Nef function.
Collapse
Affiliation(s)
- Jolien Vermeire
- Department of Clinical Chemistry, Microbiology and Immunology, Ghent University, Belgium
| | | | | | | |
Collapse
|
22
|
Klase Z, Houzet L, Jeang KT. Replication competent HIV-1 viruses that express intragenomic microRNA reveal discrete RNA-interference mechanisms that affect viral replication. Cell Biosci 2011; 1:38. [PMID: 22112720 PMCID: PMC3256098 DOI: 10.1186/2045-3701-1-38] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 11/23/2011] [Indexed: 03/15/2023] Open
Abstract
BACKGROUND It remains unclear whether retroviruses can encode and express an intragenomic microRNA (miRNA). Some have suggested that processing by the Drosha and Dicer enzymes might preclude the viability of a replicating retroviral RNA genome that contains a cis-embedded miRNA. To date, while many studies have shown that lentiviral vectors containing miRNAs can transduce mammalian cells and express the inserted miRNA efficiently, no study has examined the impact on the replication of a lentivirus such as HIV-1 after the deliberate intragenomic insertion of a bona fide miRNA. RESULTS We have constructed several HIV-1 molecular clones, each containing a discrete cellular miRNA positioned in Nef. These retroviral genomes express the inserted miRNA and are generally replication competent in T-cells. The inserted intragenomic miRNA was observed to elicit two different consequences for HIV-1 replication. First, the expression of miRNAs with predicted target sequences in the HIV-1 genome was found to reduce viral replication. Second, in one case, where an inserted miRNA was unusually well-processed by Drosha, this processing event inhibited viral replication. CONCLUSION This is the first study to examine in detail the replication competence of HIV-1 genomes that express cis-embedded miRNAs. The results indicate that a replication competent retroviral genome is not precluded from encoding and expressing a viral miRNA.
Collapse
Affiliation(s)
- Zachary Klase
- Molecular Virology Section, Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, Bethesda MD, 20892, USA.
| | | | | |
Collapse
|
23
|
Sugiyama R, Naganuma H, Nishitsuji H, Takaku H. Human immunodeficiency virus-1 Nef suppresses Hsp70-mediated Tat activation. FEBS Lett 2011; 585:3367-71. [PMID: 21970979 DOI: 10.1016/j.febslet.2011.09.029] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 09/05/2011] [Accepted: 09/19/2011] [Indexed: 10/17/2022]
Abstract
The human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) contains binding sites for several host transcription factors that contribute to HIV-1 gene expression. Although previous reports have indicated that HIV-1 Nef positively or negatively regulates HIV-1 gene expression, the precise molecular mechanisms by which this occurs remain largely unknown. In this study, we report that Nef suppressed LTR-driven transcription only in the presence of HIV-1 Tat, which was localized to the cytoplasm and degraded by the proteasome. However, the depletion of Hsp70 was found to reduce the suppressive effect of Nef on HIV-1 gene expression. These results suggest that Nef suppresses Hsp70-mediated HIV-1 Tat activation.
Collapse
Affiliation(s)
- Ryuichi Sugiyama
- Department of Life and Environmental Sciences, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
| | | | | | | |
Collapse
|
24
|
Chono H, Matsumoto K, Tsuda H, Saito N, Lee K, Kim S, Shibata H, Ageyama N, Terao K, Yasutomi Y, Mineno J, Kim S, Inouye M, Kato I. Acquisition of HIV-1 resistance in T lymphocytes using an ACA-specific E. coli mRNA interferase. Hum Gene Ther 2010; 22:35-43. [PMID: 20649483 DOI: 10.1089/hum.2010.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Transcriptional activation of gene expression directed by the long terminal repeat (LTR) of HIV-1 requires both the transactivation response element (TAR) and Tat protein. HIV-1 mutants lacking a functional tat gene are not able to proliferate. Here we take a genetic approach to suppress HIV-1 replication based on Tat-dependent production of MazF, an ACA-specific endoribonuclease (mRNA interferase) from Escherichia coli. When induced, MazF is known to cause Bak- and NBK-dependent apoptotic cell death in mammalian cells. We first constructed a retroviral vector, in which the mazF (ACA-less) gene was inserted under the control of the HIV-1 LTR, which was then transduced into CD4+ T-lymphoid CEM-SS cells in such a way that, upon HIV-1 infection, the mazF gene is induced to destroy the infecting HIV-1 mRNA, preventing HIV-1 replication. Indeed, when the transduced cells were infected with HIV-1 IIIB, the viral replication was effectively inhibited, as HIV-1 IIIB p24 could not be detected in the culture medium. Consistently, not only cell growth but also the CD4 level was not affected by the infection. These results suggest that the HIV-1-LTR-regulated mazF gene was effectively induced upon HIV-1 IIIB infection, which is sufficient enough to destroy the viral mRNA from the infected HIV-1 IIIB to completely block viral proliferation in the cells, but not to affect normal cell growth. These results indicate that the T cells transduced with the HIV-1-LTR-regulated mazF gene acquire HIV-1 resistance, providing an intriguing potential for the use of the HIV-1-LTR-regulated mazF gene in anti-HIV gene therapy.
Collapse
Affiliation(s)
- Hideto Chono
- Center for Cell and Gene Therapy, Takara Bio Inc., Otsu, Shiga, Japan
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Laguette N, Brégnard C, Benichou S, Basmaciogullari S. Human immunodeficiency virus (HIV) type-1, HIV-2 and simian immunodeficiency virus Nef proteins. Mol Aspects Med 2010; 31:418-33. [PMID: 20594957 DOI: 10.1016/j.mam.2010.05.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Accepted: 05/26/2010] [Indexed: 11/19/2022]
Abstract
The genomes of all retroviruses encode the Gag Pol and Env structural proteins. Human and simian lentiviruses have acquired non-structural proteins among which Nef plays a major role in the evolution of viral infection towards an immunodeficiency syndrome. Indeed, in the absence of a functional nef gene, primate lentiviruses are far less pathogenic than their wild type counterparts. The multiple protein-protein interactions in which Nef is involved all contribute to explain the role played by Nef in HIV- and SIV-associated disease progression. This review summarizes common and distinct features among Nef proteins and how they contribute to increasing HIV and SIV fitness towards their respective hosts.
Collapse
Affiliation(s)
- Nadine Laguette
- Institut Cochin, CNRS UMR8104, Université Paris Descartes, Paris, France
| | | | | | | |
Collapse
|
26
|
Tazi J, Bakkour N, Marchand V, Ayadi L, Aboufirassi A, Branlant C. Alternative splicing: regulation of HIV-1 multiplication as a target for therapeutic action. FEBS J 2010; 277:867-76. [DOI: 10.1111/j.1742-4658.2009.07522.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
27
|
Wolf D, Witte V, Clark P, Blume K, Lichtenheld MG, Baur AS. HIV Nef Enhances Tat-Mediated Viral Transcription through a hnRNP-K-Nucleated Signaling Complex. Cell Host Microbe 2008; 4:398-408. [DOI: 10.1016/j.chom.2008.08.013] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2008] [Revised: 06/10/2008] [Accepted: 08/07/2008] [Indexed: 01/08/2023]
|
28
|
Foster JL, Garcia JV. Role of Nef in HIV-1 replication and pathogenesis. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2007; 55:389-409. [PMID: 17586321 DOI: 10.1016/s1054-3589(07)55011-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- John L Foster
- Department of Internal Medicine, University of Texas Southwestern, Medical Center, Dallas, TX 75390, USA
| | | |
Collapse
|
29
|
Kumar M, Mitra D. Heat Shock Protein 40 Is Necessary for Human Immunodeficiency Virus-1 Nef-mediated Enhancement of Viral Gene Expression and Replication. J Biol Chem 2005; 280:40041-50. [PMID: 16179353 DOI: 10.1074/jbc.m508904200] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The human immunodeficiency virus-1 (HIV-1) Nef protein, originally identified as a negative factor, has now emerged as one of the most important viral proteins necessary for viral pathogenesis and disease progression. Nef has been also implicated in viral infectivity and replication, however, the molecular mechanism of Nef-induced viral gene expression and replication is not clearly understood. Although involvement of heat shock proteins in viral pathogenesis has been reported earlier, a clear understanding of their role remains to be elucidated. Here we report for the first time that Nef not only interacts with heat shock protein 40 (Hsp40) but it also induces the expression of Hsp40 in HIV-1-infected cells. The interaction between Nef and Hsp40 is important for increased Hsp40 translocation into the nucleus of infected cells, which seems to facilitate viral gene expression by becoming part of the cyclin-dependent kinase 9-associated transcription complex regulating long terminal repeat-mediated gene expression. The finding is consistent with the failure of the nef-deleted virus to induce Hsp40, resulting in reduced virus production. Our data further shows that, whereas, Hsp40 overexpression induces viral gene expression, silencing of Hsp40 reduces the gene expression in a Nef-dependent manner. Thus our results clearly indicate that Hsp40 is crucial for Nef-mediated enhancement of viral gene expression and replication.
Collapse
Affiliation(s)
- Manish Kumar
- National Centre for Cell Science, Ganeshkhind, Pune-411007, India
| | | |
Collapse
|
30
|
Joseph AM, Ladha JS, Mojamdar M, Mitra D. Human immunodeficiency virus-1 Nef protein interacts with Tat and enhances HIV-1 gene expression. FEBS Lett 2003; 548:37-42. [PMID: 12885404 DOI: 10.1016/s0014-5793(03)00725-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The human immunodeficiency virus (HIV-1) Nef protein is now regarded as a regulatory protein responsible not only for establishment of infection and increased pathogenesis but also for enhancement of viral replication. However, the mechanism of Nef-induced activation of viral replication remains to be clearly understood. Using transient transfection assay, co-immunoprecipitation and pull-down analysis, we demonstrate in this report that the HIV-1 Nef protein physically interacts with Tat, the principal transactivating protein of HIV-1. Our observations with single cycle replication experiments further indicate that this interaction results not only in enhancement of Tat-induced HIV-1 long terminal repeat-mediated gene expression but also in virus production.
Collapse
|
31
|
Robinson TM, Nelson RG, Boyer JD. Parasitic infection and the polarized Th2 immune response can alter a vaccine-induced immune response. DNA Cell Biol 2003; 22:421-30. [PMID: 12906735 DOI: 10.1089/104454903767650685] [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] Open
Abstract
The AIDS epidemic in the Developing World represents a major global crisis. It is imperative that we develop an effective vaccine. Vaccines are economically the most efficient means of controlling viral infections. However, the development of a vaccine against HIV-1 has been a formidable task, and in developing countries chronic parasitic infection adds another level of complexity to AIDS vaccine development. Helminthic and protozoan infections, common in developing countries, can result in a constant state of immune activation that is characterized by a dominant Th2 type of cytokine profile, high IgE levels, and eosinophilia. Such an immune profile may have an adverse impact on the efficacy of vaccines, in particular, an HIV-1 vaccine. Indeed, the CD8 cellular immune response and the corresponding Th1 type cytokines that enhance the CD8 cellular immune response are important for clearing many viral infections. It is believed that an antigen specific CD8 cellular immune response will be an important component of an HIV-1 vaccine.
Collapse
|
32
|
Abstract
The HIV-1 is a formidable pathogen with establishment of a persistent infection based on the ability to integrate the proviral genome into chronically infected cells, and by the rapid evolution made possible by a high mutation rate and frequent recombination during the viral replication. HIV-1 has a variety of novel genes that facilitate viral persistence and regulation of HIV replication, but this virus also usurps cellular machinery for HIV replication, particularly during gene expression and virion assembly and budding. Recent success with antiretroviral therapy may be limited by the emergence HIV drug resistance and by toxicities and other requirements for successful long-term therapy. Further investigation of HIV-1 replication may allow identification of novel targets of antiretroviral therapy that may allow continued virus suppression in patients of failing current regiments, particularly drugs that target HIV-1 entry and HIV-1 integration.
Collapse
Affiliation(s)
- Monique R Ferguson
- Department of Internal Medicine, Division of Infectious Diseases, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0435, USA.
| | | | | | | |
Collapse
|
33
|
Shugurova I, Bobrisheva I, Surkova I, Grivennikov I, Tarantul V. The expression of HIV-1 tat and nef genes induces cell-specific changes in growth properties and morphology of different types of rat cells. Cell Prolif 2002; 35:237-45. [PMID: 12153615 PMCID: PMC6496306 DOI: 10.1046/j.1365-2184.2002.00244.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Among the viral regulatory genes the tat and nef genes of HIV-1 encode the proteins playing a central role in viral replication and exerting pleiotropic effects on the survival and growth of the cells. These effects differ in various cell types, possibly due to the use of genes from different HIV-1 isolates. In this work, we studied the effects of the tat and nef genes on three types of cultured rat cells: primary embryo fibroblasts, pseudonormal Rat-2, and pheochromocytoma PC12. Both genes affected growth properties and morphology of cells, the effects being cell-specific. The proliferative activity of both Rat-2 and PC12 cells was considerably increased after transfection with the tat gene. In primary rat embryo fibroblasts the tat gene induced multilayered foci. More importantly, it was shown that the efficiency of transformation was higher in cells coexpressing tat and nef. The nef gene caused considerable suppression of Rat-2 cell proliferation, but no changes in their morphology. The nef gene transfection of PC12 cells also led to suppression of their proliferative activity. In addition, cellular agglomerates which were morphologically similar to multinuclear syncytial cells were detected in these cells for the first time.
Collapse
Affiliation(s)
- Irina Shugurova
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Irina Bobrisheva
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Irina Surkova
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Igor Grivennikov
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Vyacheslav Tarantul
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| |
Collapse
|
34
|
Hayashi N, Matsubara M, Jinbo Y, Titani K, Izumi Y, Matsushima N. Nef of HIV-1 interacts directly with calcium-bound calmodulin. Protein Sci 2002; 11:529-37. [PMID: 11847276 PMCID: PMC2373460 DOI: 10.1110/ps.23702] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
It was recently found that the myristoyl group of CAP-23/NAP-22, a neuron-specific protein kinase C substrate, is essential for the interaction between the protein and Ca(2+)-bound calmodulin (Ca(2+)/CaM). Based on the N-terminal amino acid sequence alignment of CAP-23/NAP-22 and other myristoylated proteins, including the Nef protein from human immunodeficiency virus (HIV), we proposed a new hypothesis that the protein myristoylation plays important roles in protein-calmodulin interactions. To investigate the possibility of direct interaction between Nef and calmodulin, we performed structural studies of Ca(2+)/CaM in the presence of a myristoylated peptide corresponding to the N-terminal region of Nef. The dissociation constant between Ca(2+)/CaM and the myristoylated Nef peptide was determined to be 13.7 nM by fluorescence spectroscopy analyses. The NMR experiments indicated that the chemical shifts of some residues on and around the hydrophobic clefts of Ca(2+)/CaM changed markedly in the Ca(2+)/CaM-Nef peptide complex with the molar ratio of 1:2. Correspondingly, the radius of gyration determined by the small angle X-ray scattering measurements is 2-3 A smaller that of Ca(2+)/CaM alone. These results demonstrate clearly that Nef interacts directly with Ca(2+)/CaM.
Collapse
Affiliation(s)
- Nobuhiro Hayashi
- Division of Biomedical Polymer Science, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi 470-1192, Japan.
| | | | | | | | | | | |
Collapse
|
35
|
Abstract
Primate lentiviruses encode a small protein designated Nef that has been shown to be a major determinant of virus pathogenicity. Nef regulates multiple host factors in order to optimize the cellular environment for virus replication. The mechanisms by which this small protein modulates distinct host cell properties provide intriguing insight into the intricate interaction between virus and host.
Collapse
Affiliation(s)
- Vivek K Arora
- Department of Internal Medicine, Division of Infectious Diseases Y9.206, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Blvd., Dallas, TX 75390-9113, USA.
| | | | | |
Collapse
|
36
|
Cramer LA, Frelinger JA. Dendritic cells transduced with HIV Nef express normal levels of HLA-A and HLA-B class I molecules. J Acquir Immune Defic Syndr 2001; 27:417-25. [PMID: 11511817 DOI: 10.1097/00126334-200108150-00001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
HIV Nef protein is important for viral pathogenesis and disease progression. Nef downregulates CD4 and major histocompatibility antigens on the surface of HIV-infected T cells. HIV also infects dendritic cells. We wanted to determine if Nef had a similar function in professional antigen-presenting cells, where downregulation of Class I could have important effects on the initiation of HIV specific cytolytic T cell responses. We infected human dendritic cells with adenovirus expressing Nef. In contrast to T cells and Hela cells, HLA-A and HLA-B molecules are not downregulated nor are other class I molecules increased. We show that, in dendritic cells, HIV Nef has little effect on CD4 or Class I expression.
Collapse
Affiliation(s)
- L A Cramer
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC 27599-7290, USA
| | | |
Collapse
|
37
|
Dendritic Cells Transduced With HIV Nef Express Normal Levels of HLA-A and HLA-B Class I Molecules. J Acquir Immune Defic Syndr 2001. [DOI: 10.1097/00042560-200108150-00001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
38
|
Ikuta K, Suzuki S, Horikoshi H, Mukai T, Luftig RB. Positive and negative aspects of the human immunodeficiency virus protease: development of inhibitors versus its role in AIDS pathogenesis. Microbiol Mol Biol Rev 2000; 64:725-45. [PMID: 11104817 PMCID: PMC99012 DOI: 10.1128/mmbr.64.4.725-745.2000] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
In this review we summarize multiple aspects of the human immunodeficiency virus (HIV) protease from both structural and functional viewpoints. After an introductory overview, we provide an up-to-date status report on protease inhibitors (PI). This proceeds from a discussion of PI structural design, to how PI are optimally utilized in highly active antiretroviral triple therapy (one PI along with two reverse transcriptase inhibitors), the emergence of PI resistance, and the natural role of secretory leukocyte PI. Then we switch to another focus: the interaction of HIV protease with other genes in acute and persistent infection, which in turn may have an effect on AIDS pathogenesis. We conclude with a discussion on future directions in HIV treatment, involving multiple-target anti-HIV therapy, vaccine development, and novel reactivation-inhibitory reagents.
Collapse
Affiliation(s)
- K Ikuta
- Department of Virology, Research Institute for Microbial Diseases (Biken), Osaka University, Suita, Osaka 565-0871, Japan.
| | | | | | | | | |
Collapse
|
39
|
Yoon K, Kim S. Lack of negative influence on the cellular transcription factors NF-kappaB and AP-1 by the nef protein of human immunodeficiency virus type 1. J Gen Virol 1999; 80 ( Pt 11):2951-2956. [PMID: 10580057 DOI: 10.1099/0022-1317-80-11-2951] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In order to investigate the molecular mechanism of the reported negative effect of the Nef protein of human immunodeficiency virus type 1 (HIV-1) on the cellular transcription factors NF-kappaB and AP-1, human T cell lines (both populations and subclones) expressing the nef gene from HIV-1 clone pNL432 were constructed. Functional expression of the nef gene was confirmed by downregulation of CD4 and MHC class I proteins on the cell surface as measured by fluorescence-activated cell sorter analysis. However, contrary to previous reports, no significant difference was found in the induced level of NF-kappaB and AP-1 activity between nef(+) and nef(-) cell lines upon stimulation by phorbol 12-myristate 13-acetate and phytohaemagglutinin, as measured by transient transfection and electromobility shift assays. These data indicate that the Nef protein does not have a negative effect on the induction of NF-kappaB and AP-1.
Collapse
Affiliation(s)
- Keejung Yoon
- Institute of Molecular Biology and Genetics, Building 105, Seoul National University, Kwan-Ak-Gu, Seoul 151-742, Korea1
| | - Sunyoung Kim
- Institute of Molecular Biology and Genetics, Building 105, Seoul National University, Kwan-Ak-Gu, Seoul 151-742, Korea1
| |
Collapse
|
40
|
Ross TM, Oran AE, Cullen BR. Inhibition of HIV-1 progeny virion release by cell-surface CD4 is relieved by expression of the viral Nef protein. Curr Biol 1999; 9:613-21. [PMID: 10375525 DOI: 10.1016/s0960-9822(99)80283-8] [Citation(s) in RCA: 203] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
BACKGROUND The human immunodeficiency virus type 1 (HIV-1) Nef protein is required for efficient virus replication in vivo and displays a number of distinct and apparently unrelated biological activities in vitro. Of these, one of the most readily demonstrated is the efficient internalization and degradation of cell-surface CD4, the receptor for the HIV-1 envelope protein. The biological purpose of this internalization has, however, remained unclear. RESULTS Using human 293T cells expressing high levels of cell-surface CD4 or CD8, we demonstrate that CD4, but not CD8, can dramatically reduce the release of infectious virions bearing the HIV-1 envelope protein and induce a concomitant increase in the accumulation of cell-associated HIV-1 structural proteins. In contrast, CD4 had no effect on the release of HIV-1 bearing a heterologous envelope protein unable to bind CD4. Nef expression totally reversed CD4-mediated inhibition but only if the CD4 used remained susceptible to Nef-induced internalization. CONCLUSIONS These results support the hypothesis that cell-surface CD4 can interact with the envelope protein present on budding HIV-1 virions to inhibit their release. The internalization and degradation of cell-surface CD4 induced by the viral Nef protein can fully reverse this inhibition and is, therefore, likely to facilitate the spread of virus in vivo.
Collapse
Affiliation(s)
- T M Ross
- Yerkes Regional Primate Research Center, Division of Microbiology and Immunology, Emory University, Atlanta, Georgia 30329, USA
| | | | | |
Collapse
|
41
|
|
42
|
Affiliation(s)
- J W Marsh
- Laboratory of Molecular Biology, NIMH, Bethesda, Maryland, 20892-4034, USA.
| |
Collapse
|
43
|
Tokunaga K, Ikuta K, Adachi A, Matsuda M, Kurata T, Kojima A. The cellular kinase binding motifs (PxxP and RR) in human immunodeficiency virus type 1 Nef protein are dispensable for producer-cell-dependent enhancement of viral entry. Virology 1999; 257:285-9. [PMID: 10329538 DOI: 10.1006/viro.1999.9682] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have recently demonstrated that human immunodeficiency virus type 1 (HIV-1) Nef is required for enhancing viral infectivity by increasing the efficiency of viral entry in a producer-cell-dependent manner, suggesting the possible involvement of a cellular factor(s) in the enhancement of viral entry. Moreover, it has been reported that a proline-rich (PxxP) motif and an Arg-Arg (RR) motif in HIV-1 Nef bind to the SH3 domain of the Src-family tyrosine kinase Hck and to a serine/threonine kinase, respectively. To address whether these cellular kinase binding motifs, PxxP and RR, could be involved in virus producer-cell-dependent enhancement of viral entry, we constructed two nef mutant proviral clones in which these motifs were mutated. The results show that the HIV-1 Nef PxxP motif, which significantly influenced viral infectivity, and the RR motif, which modestly affected viral infectivity, were both dispensable for enhanced viral entry, thus suggesting that another interaction of Nef with a cellular factor(s) is involved in the efficiency of viral entry.
Collapse
Affiliation(s)
- K Tokunaga
- Department of Pathology, National Institute of Infectious Diseases, Tokyo, 162-8640, Japan
| | | | | | | | | | | |
Collapse
|
44
|
Glushakova S, Grivel JC, Suryanarayana K, Meylan P, Lifson JD, Desrosiers R, Margolis L. Nef enhances human immunodeficiency virus replication and responsiveness to interleukin-2 in human lymphoid tissue ex vivo. J Virol 1999; 73:3968-74. [PMID: 10196292 PMCID: PMC104175 DOI: 10.1128/jvi.73.5.3968-3974.1999] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The nef gene is important for the pathogenicity associated with simian immunodeficiency virus infection in rhesus monkeys and with human immunodeficiency virus type 1 (HIV-1) infection in humans. The mechanisms by which nef contributes to pathogenesis in vivo remain unclear. We investigated the contribution of nef to HIV-1 replication in human lymphoid tissue ex vivo by studying infection with parental HIV-1 strain NL4-3 and with a nef mutant (DeltanefNL4-3). In human tonsillar histocultures, NL4-3 replicated to higher levels than DeltanefNL4-3 did. Increased virus production with NL4-3 infection was associated with increased numbers of productively infected cells and greater loss of CD4(+) T cells over time. While the numbers of productively infected T cells were increased in the presence of nef, the levels of viral expression and production per infected T cell were similar whether the nef gene was present or not. Exogenous interleukin-2 (IL-2) increased HIV-1 production in NL4-3-infected tissue in a dose-dependent manner. In contrast, DeltanefNL4-3 production was enhanced only marginally by IL-2. Thus, Nef can facilitate HIV-1 replication in human lymphoid tissue ex vivo by increasing the numbers of productively infected cells and by increasing the responsiveness to IL-2 stimulation.
Collapse
Affiliation(s)
- S Glushakova
- Laboratory of Molecular and Cellular Biophysics, National Institute of Child Health and Human Development, Bethesda, Maryland 20892, USA
| | | | | | | | | | | | | |
Collapse
|
45
|
Meylan PR, Baumgartner M, Ciuffi A, Munoz M, Sahli R. The nef gene controls syncytium formation in primary human lymphocytes and macrophages infected by HIV type 1. AIDS Res Hum Retroviruses 1998; 14:1531-42. [PMID: 9840286 DOI: 10.1089/aid.1998.14.1531] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
nef, the 3'-most open reading frame of HIV, has been reported to enhance HIV replication in various host cell types and to promote in vivo replication and pathogenesis. The mechanism underlying the increased in vivo viral replication is still unclear. We have examined the effect of a nef deletion on the infection of primary human CD4+ T lymphocytes and macrophages, using clones with nef and env sequences derived, respectively, from T cell- and macrophage-tropic viruses. The deletion of nef enhanced the formation of syncytia in CD4+ T lymphocytes infected with macrophage-tropic clones, despite a severalfold reduced viral production. No such enhancement of syncytium formation was observed in CD4+ T lymphocytes infected with a T cell line-tropic clone, but in this clone, the deletion of nef imparted a more severe replication defect. A similar increase in syncytium formation was observed in primary human macrophages infected with nef-deleted clones compared with wild-type counterparts, except under conditions in which the deletion of nef markedly reduced viral replication. We could not demonstrate an enhanced cell surface expression of HIV-1 envelope in lymphocytes infected with nef-deficient clones to explain the increased syncytium formation. In enhancing the HIV-1 cytopathic effect, the deletion of nef might curtail virus production by infected cells, and thus explain in part the reduced viral load observed in vivo in hosts infected with nef-deficient viruses.
Collapse
Affiliation(s)
- P R Meylan
- Institute of Microbiology and Division of Infectious Diseases, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | | | | | | | | |
Collapse
|
46
|
Heidecker G, Muñoz H, Lloyd P, Hodge D, Ruscetti FW, Morton WR, Hu S, Benveniste RE. Macaques infected with cloned simian immunodeficiency virus show recurring nef gene alterations. Virology 1998; 249:260-74. [PMID: 9791018 DOI: 10.1006/viro.1998.9325] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We compared nef gene sequences isolated by polymerase chain reaction from peripheral blood lymphocyte DNA of macaques that had been inoculated with either biologically (E11S) or molecularly (clone 8) cloned SIV/Mne. Two samples from each animal obtained either early (weeks 2-8) or late (weeks 21-137) after infection were analyzed. Three substitutions in the predicted Nef amino acid sequence were seen in all animals at the late time point, and two other substitutions were seen in all except one. Two of the common exchanges are located approximately 40 residues apart in the Nef core sequence but are juxtaposed on the tertiary structure as judged by computer modeling using the structure of the HIV Nef core protein as a guide. Most recurrent in vivo changes replaced a residue found in the cloned Nef sequence with one present in a consensus derived by aligning the Nef sequences of the SIV/Sm clade. Recombinant virus containing a macaque-adapted (MA nef) nef on the clone 8 backbone was 3-fold more infectious on SMAGI cells than the original virus. A lymphocyte line infected with SIV-clone 8-MAnef contained a large proportion of cells carrying provirus with defective nef genes. These findings suggest that the nef gene of the cloned SIV/Mne had undergone attenuating mutations during propagation in tissue culture that were "corrected" in vivo.
Collapse
Affiliation(s)
- G Heidecker
- SAIC Frederick, National Cancer Institute-Frederick Cancer Research and Development Center, Frederick, Maryland, 21702, USA.
| | | | | | | | | | | | | | | |
Collapse
|
47
|
Tokunaga K, Kojima A, Kurata T, Ikuta K, Inubushi R, Shimano R, Kawamura M, Akari H, Koyama AH, Adachi A. Producer cell-dependent requirement of the Nef protein for efficient entry of HIV-1 into cells. Biochem Biophys Res Commun 1998; 250:565-8. [PMID: 9784383 DOI: 10.1006/bbrc.1998.9346] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A proviral nef gene mutant of human immunodeficiency virus type 1 (HIV-1) was evaluated for its defective early replication step. Virus stocks were prepared from six CD4-positive and -negative cell lines transfected with wild-type (wt) or the nef mutant clone and inoculated into two target CD4-positive cell lines to monitor the efficiency of viral entry process. The nef mutant virions produced in one cell line exhibited a severe defect in the entry process, although those produced in the other five cell lines were only slightly less efficient than the wt virions at entering into cells. These results have demonstrated that the HIV-1 Nef is critical for efficient viral entry in a producer cell-dependent manner.
Collapse
Affiliation(s)
- K Tokunaga
- Department of Pathology, National Institute of Infectious Diseases, Tokyo, 162-8640, Japan
| | | | | | | | | | | | | | | | | | | |
Collapse
|
48
|
Yoon K, Kestler HW, Kim S. Growth properties of HSIVnef: HIV-1 containing the nef gene from pathogenic molecular clone SIVmac239. Virus Res 1998; 57:27-34. [PMID: 9833883 DOI: 10.1016/s0168-1702(98)00076-8] [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] [Indexed: 11/18/2022]
Abstract
To elucidate the function of nef, we constructed infectious chimeric clones between human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV) of macaques, by deleting a part of the nef sequence from the HIV-1 genome and inserting the entire nef gene from the pathogenic molecular clone, SIVmac239. We have named this construct HSIVnef. While there was no difference in the replication kinetics of HSIVnef+ and HSIVnef- in transformed cell lines, there was a profound difference in the replication of these virus in primary cells. These data indicated that the SIV nef gene could complement the functions of the HIV-1 nef gene in the context of the HIV-1 genome, providing further evidence that results observed in the macaque model are relevant to HIV infections in man. HSIVnef is a useful model for the study of the nef gene.
Collapse
Affiliation(s)
- K Yoon
- Institute for Molecular Biology and Genetics, Seoul National University, South Korea
| | | | | |
Collapse
|
49
|
Lindemann D, Rethwilm A. Characterization of a human foamy virus 170-kilodalton Env-Bet fusion protein generated by alternative splicing. J Virol 1998; 72:4088-94. [PMID: 9557698 PMCID: PMC109638 DOI: 10.1128/jvi.72.5.4088-4094.1998] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Primate foamy viruses (FVs) express, in addition to the 130-kDa envelope protein, a 170-kDa glycoprotein, which reacts with antisera specific for the envelope and Bel proteins. We determined the exact nature of this 170-kDa glycoprotein by using the molecularly cloned human FV (HFV). Radioimmunoprecipitation analysis of 293T cells transfected with appropriate expression constructs by using antisera specific for the HFV Env, Bel1, and Bel2 proteins, as well as reverse transcription-PCR analysis of HFV-infected cells, demonstrated that this protein is an Env-Bet fusion protein that is secreted into the supernatant. However, it is only loosely associated, or not associated, with viral particles. gp170 is generated by an alternatively spliced Env mRNA using a splice donor and splice acceptor pair localized within the env open reading frame (ORF), which is normally used to generate Bell and Bet transcripts derived from the internal promoter within the env ORF. gp170 is expressed at a level 30 to 50% of the Env precursor gp130. However, it alone does not confer infectivity to HFV particles, because capsids derived from proviruses expressing only the gp170 were not released into the supernatant. In contrast, viruses derived from proviral clones deficient in gp170 expression showed similar in vitro infectivity and replication kinetics to wild-type virus. Furthermore, both types of viruses were inactivated to a similar extent by neutralizing sera, indicating that shedding of gp170 probably does not affect the humoral immune response in the infected host.
Collapse
Affiliation(s)
- D Lindemann
- Institut für Virologie und Immunbiologie, Universität Würzburg, Germany.
| | | |
Collapse
|
50
|
Inoshima Y, Miyazawa T, Mikami T. In vivo functions of the auxiliary genes and regulatory elements of feline immunodeficiency virus. Vet Microbiol 1998; 60:141-53. [PMID: 9646446 DOI: 10.1016/s0378-1135(98)00157-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Feline immunodeficiency virus (FIV) is a widespread lentivirus of domestic cats that causes an acquired immunodeficiency syndrome (AIDS)-like disease similar to human AIDS caused by human immunodeficiency virus. FIV has a complex genome structure including structural, enzymatic and auxiliary genes and regulatory elements. In this article, we review the in vivo roles of some of these FIV auxiliary genes and regulatory elements, especially focusing on the dUTPase, vif, and ORF-A genes and AP-1 binding site in the enhancer region of the long terminal repeat, by comparison with those of other non-primate lentiviruses. These genes and elements are considered to be important for viral replication, immunological response and pathogenesis in cats.
Collapse
Affiliation(s)
- Y Inoshima
- Department of Veterinary Microbiology, Graduate School of Agricultural and Life Sciences, University of Tokyo, Japan
| | | | | |
Collapse
|