1
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Molnar SM, Kim Y, Wieczorek L, Williams A, Patil KA, Khatkar P, Santos MF, Mensah G, Lorico A, Polonis VR, Kashanchi F. Extracellular vesicle isolation methods identify distinct HIV-1 particles released from chronically infected T-cells. J Extracell Vesicles 2024; 13:e12476. [PMID: 38978287 PMCID: PMC11231049 DOI: 10.1002/jev2.12476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 06/16/2024] [Indexed: 07/10/2024] Open
Abstract
The current study analyzed the intersecting biophysical, biochemical, and functional properties of extracellular particles (EPs) with the human immunodeficiency virus type-1 (HIV-1) beyond the currently accepted size range for HIV-1. We isolated five fractions (Frac-A through Frac-E) from HIV-infected cells by sequential differential ultracentrifugation (DUC). All fractions showed a heterogeneous size distribution with median particle sizes greater than 100 nm for Frac-A through Frac-D but not for Frac-E, which contained small EPs with an average size well below 50 nm. Synchronized and released cultures contained large infectious EPs in Frac-A, with markers of amphisomes and viral components. Additionally, Frac-E uniquely contained EPs positive for CD63, HSP70, and HIV-1 proteins. Despite its small average size, Frac-E contained membrane-protected viral integrase, detectable only after SDS treatment, indicating that it is enclosed in vesicles. Single particle analysis with dSTORM further supported these findings as CD63, HIV-1 integrase, and the viral surface envelope (Env) glycoprotein (gp) colocalized on the same Frac-E particles. Surprisingly, Frac-E EPs were infectious, and infectivity was significantly reduced by immunodepleting Frac-E with anti-CD63, indicating the presence of this protein on the surface of infectious small EPs in Frac-E. To our knowledge, this is the first time that extracellular vesicle (EV) isolation methods have identified infectious small HIV-1 particles (smHIV-1) that are under 50 nm. Collectively, our data indicate that the crossroads between EPs and HIV-1 potentially extend beyond the currently accepted biophysical properties of HIV-1, which may have further implications for viral pathogenesis.
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Affiliation(s)
- Sebastian M. Molnar
- Military HIV‐1 Research ProgramWalter Reed Army Institute of ResearchSilver SpringMarylandUSA
- Henry M. Jackson Foundation for the Advancement of Military MedicineBethesdaMarylandUSA
- Laboratory of Molecular Virology, School of System BiologyGeorge Mason UniversityManassasVirginiaUSA
| | - Yuriy Kim
- Laboratory of Molecular Virology, School of System BiologyGeorge Mason UniversityManassasVirginiaUSA
| | - Lindsay Wieczorek
- Military HIV‐1 Research ProgramWalter Reed Army Institute of ResearchSilver SpringMarylandUSA
- Henry M. Jackson Foundation for the Advancement of Military MedicineBethesdaMarylandUSA
| | - Anastasia Williams
- Laboratory of Molecular Virology, School of System BiologyGeorge Mason UniversityManassasVirginiaUSA
| | - Kajal Ashok Patil
- Laboratory of Molecular Virology, School of System BiologyGeorge Mason UniversityManassasVirginiaUSA
| | - Pooja Khatkar
- Laboratory of Molecular Virology, School of System BiologyGeorge Mason UniversityManassasVirginiaUSA
| | - Mark F. Santos
- College of MedicineTouro University NevadaHendersonNevadaUSA
| | - Gifty Mensah
- Laboratory of Molecular Virology, School of System BiologyGeorge Mason UniversityManassasVirginiaUSA
| | - Aurelio Lorico
- College of MedicineTouro University NevadaHendersonNevadaUSA
| | - Victoria R. Polonis
- Military HIV‐1 Research ProgramWalter Reed Army Institute of ResearchSilver SpringMarylandUSA
| | - Fatah Kashanchi
- Laboratory of Molecular Virology, School of System BiologyGeorge Mason UniversityManassasVirginiaUSA
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2
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Iwamoto Y, Ye AA, Shirazinejad C, Hurley JH, Drubin DG. Kinetic investigation reveals an HIV-1 Nef-dependent increase in AP-2 recruitment and productivity at endocytic sites. Mol Biol Cell 2024; 35:ar9. [PMID: 37938925 PMCID: PMC10881171 DOI: 10.1091/mbc.e23-04-0126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 10/24/2023] [Accepted: 11/02/2023] [Indexed: 11/10/2023] Open
Abstract
The HIV-1 accessory protein Nef hijacks clathrin adaptors to degrade or mislocalize host proteins involved in antiviral defenses. Here, using quantitative live-cell microscopy in genome-edited Jurkat cells, we investigate the impact of Nef on clathrin-mediated endocytosis (CME), a major pathway for membrane protein internalization in mammalian cells. Nef is recruited to CME sites on the plasma membrane, and this recruitment is associated with an increase in the recruitment and lifetime of the CME coat protein AP-2 and the late-arriving CME protein dynamin2. Furthermore, we find that CME sites that recruit Nef are more likely to recruit dynamin2 and transferrin, suggesting that Nef recruitment to CME sites promotes site maturation to ensure high efficiency in host protein downregulation. Implications of these observations for HIV-1 infection are discussed.
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Affiliation(s)
- Yuichiro Iwamoto
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Anna A. Ye
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Cyna Shirazinejad
- Biophysics Graduate Group, University of California, Berkeley, Berkeley, CA 94720
| | - James H. Hurley
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720
- Biophysics Graduate Group, University of California, Berkeley, Berkeley, CA 94720
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720
| | - David G. Drubin
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720
- Biophysics Graduate Group, University of California, Berkeley, Berkeley, CA 94720
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3
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Sharma M, Marin M, Wu H, Prikryl D, Melikyan GB. Human Immunodeficiency Virus 1 Preferentially Fuses with pH-Neutral Endocytic Vesicles in Cell Lines and Human Primary CD4+ T-Cells. ACS NANO 2023; 17:17436-17450. [PMID: 37589658 PMCID: PMC10510587 DOI: 10.1021/acsnano.3c05508] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 08/14/2023] [Indexed: 08/18/2023]
Abstract
Despite extensive efforts, the principal sites of productive HIV-1 entry in different target cells─plasma membrane (PM) vs endosomes─remain controversial. To delineate the site(s) of HIV-1 fusion, we implemented a triple labeling approach that involves tagging pseudoviruses with the fluid-phase viral content marker, iCherry, the viral membrane marker, DiD, and the extraviral pH sensor, ecliptic pHluorin. The viral content marker iCherry is released into the cytoplasm upon virus-cell fusion irrespective of the sites of fusion. In contrast, the extent of dilution of the membrane marker upon fusion with the PM (loss of signal) vs the endosomal membrane (no change in punctate DiD appearance) discriminates between the principal sites of viral fusion. Additionally, ecliptic pHluorin incorporated into the viral membrane reports whether virus fusion occurs in acidic endosomes. Real-time single virus imaging in living HeLa-derived cells, a CD4+ T-cell line, and activated primary human CD4+ T-cells revealed a strong (80-90%) HIV-1 preference for fusion with endosomes. Intriguingly, we observed HIV-1 fusion only with pH-neutral intracellular vesicles and never with acidified endosomes. These endocytic fusion events are likely culminating in productive infection since endocytic inhibitors, such as EIPA, Pitstop2, and Dynasore, as well as a dominant-negative dynamin-2 mutant, inhibited HIV-1 infection in HeLa-derived and primary CD4+ T-cells. Furthermore, the inhibition of endocytosis in HeLa-derived cells promoted hemifusion at the PM but abrogated complete fusion. Collectively, these data reveal that the primary HIV-1 entry pathway in diverse cell types is through fusion with pH-neutral intracellular vesicles.
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Affiliation(s)
- Manish Sharma
- Department
of Pediatrics, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia 30322, United States
- Children’s
Healthcare of Atlanta, Atlanta, Georgia 30322, United States
| | - Mariana Marin
- Department
of Pediatrics, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia 30322, United States
- Children’s
Healthcare of Atlanta, Atlanta, Georgia 30322, United States
| | - Hui Wu
- Department
of Pediatrics, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia 30322, United States
| | - David Prikryl
- Department
of Pediatrics, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia 30322, United States
| | - Gregory B. Melikyan
- Department
of Pediatrics, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia 30322, United States
- Children’s
Healthcare of Atlanta, Atlanta, Georgia 30322, United States
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4
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Bhardwaj V, Singh A, Choudhary A, Dalavi R, Ralte L, Chawngthu RL, Senthil Kumar N, Vijay N, Chande A. HIV-1 Vpr induces ciTRAN to prevent transcriptional repression of the provirus. SCIENCE ADVANCES 2023; 9:eadh9170. [PMID: 37672576 PMCID: PMC10482341 DOI: 10.1126/sciadv.adh9170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 08/02/2023] [Indexed: 09/08/2023]
Abstract
The functional consequences of circular RNA (circRNA) expression on HIV-1 replication are largely unknown. Using a customized protocol involving direct RNA nanopore sequencing, here, we captured circRNAs from HIV-1-infected T cells and identified ciTRAN, a circRNA that modulates HIV-1 transcription. We found that HIV-1 infection induces ciTRAN expression in a Vpr-dependent manner and that ciTRAN interacts with SRSF1, a protein known to repress HIV-1 transcription. Our results suggest that HIV-1 hijacks ciTRAN to exclude serine/arginine-rich splicing factor 1 (SRSF1) from the viral transcriptional complex, thereby promoting efficient viral transcription. In addition, we demonstrate that an SRSF1-inspired mimic can inhibit viral transcription regardless of ciTRAN induction. The hijacking of a host circRNA thus represents a previously unknown facet of primate lentiviruses in overcoming transmission bottlenecks.
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Affiliation(s)
- Vipin Bhardwaj
- Molecular Virology Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Bhopal, India
| | - Aman Singh
- Molecular Virology Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Bhopal, India
| | - Aditi Choudhary
- Molecular Virology Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Bhopal, India
| | - Rishikesh Dalavi
- Molecular Virology Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Bhopal, India
| | | | | | | | - Nagarjun Vijay
- Computational and Evolutionary Genomics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Bhopal, India
| | - Ajit Chande
- Molecular Virology Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Bhopal, India
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5
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Firrito C, Bertelli C, Rosa A, Chande A, Ananth S, van Dijk H, Fackler OT, Stoneham C, Singh R, Guatelli J, Pizzato M. A Conserved Acidic Residue in the C-Terminal Flexible Loop of HIV-1 Nef Contributes to the Activity of SERINC5 and CD4 Downregulation. Viruses 2023; 15:652. [PMID: 36992361 PMCID: PMC10057511 DOI: 10.3390/v15030652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 02/22/2023] [Accepted: 02/27/2023] [Indexed: 03/05/2023] Open
Abstract
The host transmembrane protein SERINC5 is incorporated into retrovirus particles and inhibits HIV-1 infectivity. The lentiviral Nef protein counteracts SERINC5 by downregulating it from the cell surface and preventing its incorporation into virions. The ability of Nef to antagonize the host factor varies in magnitude between different HIV-1 isolates. After having identified a subtype H nef allele unable to promote HIV-1 infectivity in the presence of SERINC5, we investigated the molecular determinants responsible for the defective counteraction of the host factor. Chimeric molecules with a subtype C Nef highly active against SERINC5 were constructed to locate Nef residues crucial for the activity against SERINC5. An Asn at the base of the C-terminal loop of the defective nef allele was found in place of a highly conserved acidic residue (D/E 150). The conversion of Asn to Asp restored the ability of the defective Nef to downregulate SERINC5 and promote HIV-1 infectivity. The substitution was also found to be crucial for the ability of Nef to downregulate CD4, but not for Nef activities that do not rely on the internalization of receptors from the cell surface, suggesting a general implication in promoting clathrin-mediated endocytosis. Accordingly, bimolecular fluorescence complementation revealed that the conserved acidic residue contributes to the recruitment of AP2 by Nef. Altogether, our results confirm that Nef downregulates SERINC5 and CD4 by engaging a similar machinery and indicates that, in addition to the di-leucine motif, other residues in the C-terminal flexible loop are important for the ability of the protein to sustain clathrin-mediated endocytosis.
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Affiliation(s)
- Claudia Firrito
- Department of Cellular, Computational and integrative Biology, University of Trento, 38123 Trento, Italy
| | - Cinzia Bertelli
- Department of Cellular, Computational and integrative Biology, University of Trento, 38123 Trento, Italy
| | - Annachiara Rosa
- Department of Cellular, Computational and integrative Biology, University of Trento, 38123 Trento, Italy
| | - Ajit Chande
- Department of Cellular, Computational and integrative Biology, University of Trento, 38123 Trento, Italy
| | - Swetha Ananth
- Department of Infectious Diseases, Integrative Virology, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Hannah van Dijk
- Department of Infectious Diseases, Integrative Virology, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Oliver T. Fackler
- Department of Infectious Diseases, Integrative Virology, University Hospital Heidelberg, 69120 Heidelberg, Germany
- German Center for Infection Research (DZIF), 69120 Heidelberg, Germany
| | - Charlotte Stoneham
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
- VA San Diego Healthcare System, San Diego, CA 92161, USA
| | - Rajendra Singh
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
- VA San Diego Healthcare System, San Diego, CA 92161, USA
| | - John Guatelli
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
- VA San Diego Healthcare System, San Diego, CA 92161, USA
| | - Massimo Pizzato
- Department of Cellular, Computational and integrative Biology, University of Trento, 38123 Trento, Italy
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6
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Chakravarty A, Yang PL. Targeted protein degradation as an antiviral approach. Antiviral Res 2023; 210:105480. [PMID: 36567024 PMCID: PMC10178900 DOI: 10.1016/j.antiviral.2022.105480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 12/01/2022] [Indexed: 12/24/2022]
Abstract
Targeted protein degradation (TPD) has emerged as a new modality in drug discovery. In this approach, small molecules are used to drive degradation of the target protein of interest. Whereas most direct-acting antivirals (DAAs) inhibit or derange the activity of their viral protein targets and have occupancy-driven pharmacology, small molecules with a TPD-based mechanism have event-driven pharmacology exerted through their ability to induce target degradation. These contrasting mechanisms can result in significant differences in drug efficacy and pharmacodynamics that may be useful in the development of new classes of antivirals. While now being widely pursued in cancer biology and autoimmune disease, TPD has not yet been widely applied as an antiviral strategy. Here, we briefly review TPD pharmacology along with the current status of tools available for developing small molecules that achieve antiviral activity through a TPD mechanism. We also highlight aspects of TPD that may be especially useful in the development of antivirals and that we hope will motivate pursuit of TPD-based antivirals by the antivirals research community.
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Affiliation(s)
- Antara Chakravarty
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Priscilla L Yang
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, 94305, USA.
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7
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Ramirez PW, Vollbrecht T, Acosta FM, Suarez M, Angerstein AO, Wallace J, O' Connell RM, Guatelli J. Nef enhances HIV-1 replication and infectivity independently of SERINC5 in CEM T cells. Virology 2023; 578:154-162. [PMID: 36577173 PMCID: PMC10484624 DOI: 10.1016/j.virol.2022.12.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 12/14/2022] [Accepted: 12/15/2022] [Indexed: 12/25/2022]
Abstract
A primary function of HIV-1 Nef is the enhancement of viral infectivity and replication. Whether counteraction of the antiretroviral proteins SERINC3 and SERINC5 is the cause of this positive influence on viral growth-rate and infectivity remains unclear. Here, we utilized CRISPR/Cas9 to knockout SERINC3 and SERINC5 in a leukemic CD4-positive T cell line (CEM) that displays nef-related infectivity and growth-rate phenotypes. Viral replication was attenuated in CEM cells infected with HIV-1 lacking Nef (HIV-1ΔNef). This attenuated growth-rate phenotype was observed regardless of whether the coding regions of the serinc3 or serinc5 genes were intact. Moreover, knockout of serinc5 alone or of both serinc5 and serinc3 together failed to restore the infectivity of HIV1ΔNef virions produced from infected CEM cells. Our results corroborate a similar study using another T-lymphoid cell line (MOLT-3) and indicate that the antagonism of SERINC3 and SERINC5 does not fully explain the virology of HIV-1 lacking Nef.
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Affiliation(s)
- Peter W Ramirez
- Department of Biological Sciences, California State University Long Beach, Long Beach, CA, USA.
| | - Thomas Vollbrecht
- Department of Medicine, University of California San Diego, La Jolla, CA, USA; VA San Diego Healthcare System, San Diego, CA, USA
| | - Francisco M Acosta
- Department of Biological Sciences, California State University Long Beach, Long Beach, CA, USA
| | | | - Aaron O Angerstein
- Department of Medicine, University of California San Diego, La Jolla, CA, USA; VA San Diego Healthcare System, San Diego, CA, USA
| | - Jared Wallace
- Division of Microbiology and Immunology, Department of Pathology, The University of Utah, Salt Lake City, UT, USA
| | - Ryan M O' Connell
- Division of Microbiology and Immunology, Department of Pathology, The University of Utah, Salt Lake City, UT, USA
| | - John Guatelli
- Department of Medicine, University of California San Diego, La Jolla, CA, USA; VA San Diego Healthcare System, San Diego, CA, USA
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8
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Zhao F, Xu F, Liu X, Hu Y, Wei L, Fan Z, Wang L, Huang Y, Mei S, Guo L, Yang L, Cen S, Wang J, Liang C, Guo F. SERINC5 restricts influenza virus infectivity. PLoS Pathog 2022; 18:e1010907. [PMID: 36223419 PMCID: PMC9591065 DOI: 10.1371/journal.ppat.1010907] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 10/24/2022] [Accepted: 09/30/2022] [Indexed: 11/16/2022] Open
Abstract
SERINC5 is a multi-span transmembrane protein that is incorporated into HIV-1 particles in producing cells and inhibits HIV-1 entry. Multiple retroviruses like HIV-1, equine infectious anemia virus and murine leukemia virus are subject to SERINC5 inhibition, while HIV-1 pseudotyped with envelope glycoproteins of vesicular stomatitis virus and Ebola virus are resistant to SERINC5. The antiviral spectrum and the underlying mechanisms of SERINC5 restriction are not completely understood. Here we show that SERINC5 inhibits influenza A virus infection by targeting virus-cell membrane fusion at an early step of infection. Further results show that different influenza hemagglutinin (HA) subtypes exhibit diverse sensitivities to SERINC5 restriction. Analysis of the amino acid sequences of influenza HA1 strains indicates that HA glycosylation sites correlate with the sensitivity of influenza HA to SERINC5, and the inhibitory effect of SERINC5 was lost when certain HA glycosylation sites were mutated. Our study not only expands the antiviral spectrum of SERINC5, but also reveals the role of viral envelope glycosylation in resisting SERINC5 restriction.
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Affiliation(s)
- Fei Zhao
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, and Center for AIDS Research, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, P. R. China
| | - Fengwen Xu
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, and Center for AIDS Research, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, P. R. China
| | - Xiaoman Liu
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, and Center for AIDS Research, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, P. R. China
| | - Yamei Hu
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, and Center for AIDS Research, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, P. R. China
| | - Liang Wei
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, and Center for AIDS Research, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, P. R. China
| | - Zhangling Fan
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, and Center for AIDS Research, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, P. R. China
| | - Liming Wang
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, and Center for AIDS Research, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, P. R. China
| | - Yu Huang
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, and Center for AIDS Research, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, P. R. China
| | - Shan Mei
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, and Center for AIDS Research, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, P. R. China
| | - Li Guo
- NHC Key Laboratory of Systems Biology of Pathogens and Christophe Mérieux Laboratory, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, P. R. China
| | - Long Yang
- School of Integrative Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Shan Cen
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, P. R. China
| | - Jianwei Wang
- NHC Key Laboratory of Systems Biology of Pathogens and Christophe Mérieux Laboratory, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, P. R. China
- * E-mail: (JW); (CL); (FG)
| | - Chen Liang
- McGill University AIDS Centre, Lady Davis Institute, Jewish General Hospital, Montreal, Quebec, Canada
- * E-mail: (JW); (CL); (FG)
| | - Fei Guo
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, and Center for AIDS Research, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, P. R. China
- * E-mail: (JW); (CL); (FG)
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9
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Ataollahi N, Broseghini M, Ferreira FF, Susana A, Pizzato M, Scardi P. Effect of High-Energy Milling on the Dissolution of Anti-HIV Drug Efavirenz in Different Solvents. ACS OMEGA 2021; 6:12647-12659. [PMID: 34056416 PMCID: PMC8154137 DOI: 10.1021/acsomega.1c00712] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/19/2021] [Indexed: 06/01/2023]
Abstract
The anti-HIV drug efavirenz (EFV) displays low and variable bioavailability because of its poor aqueous solubility. Ball milling is a simple and cost-effective alternative to traditional micronization to improve the solubility and dissolution rate of EFV. A multibody dynamics model was employed to optimize the milling process parameters, while the motion of the balls in the mill jar was monitored in operando. This led to a better understanding of the milling dynamics for efficient comminution and enhancement of EFV dissolution. The variability of results for different EFV batches was also considered. Depending on the EFV batch, there were intrinsic differences in how the milling affected the dissolution behavior and inhibition of HIV-1 infection. High-energy grinding is more effective on EFV materials containing an amorphous fraction; it helps to remove agglomeration and enhances dissolution. Polyvinylpyrrolidone (PVP) addition improves the dissolution by forming a hydrophilic layer on the EFV surface, thereby increasing the drug wettability. Polymorphism also affects the quality, dosage, and effectiveness of the drug. The mechanical stress effect and PVP addition on the EFV polymorphic transformation were monitored by X-ray powder diffraction, while the residual of ground EFV was collected after dissolution, analyzed by scanning electron microscopy, and provided insights into the morphological changes.
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Affiliation(s)
- Narges Ataollahi
- Department
of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano, 77, Trento 38123, Italy
| | - Marica Broseghini
- Helmholtz
Zentrum Geesthacht (HZG), Institute of Coastal
Research, Max-Planck-Straße 1, Geesthacht 21502, Germany
| | - Fabio F. Ferreira
- Center
for Natural and Human Sciences, Federal
University of ABC, Santo
André, SP 09210-580, Brazil
| | - Alberto Susana
- Centre
for Integrative Biology, University of Trento, Via Sommarive, 9, Trento 38123, Italy
| | - Massimo Pizzato
- Centre
for Integrative Biology, University of Trento, Via Sommarive, 9, Trento 38123, Italy
| | - Paolo Scardi
- Department
of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano, 77, Trento 38123, Italy
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10
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Selective Disruption of SERINC5 Antagonism by Nef Impairs SIV Replication in Primary CD4 + T Cells. J Virol 2021; 95:JVI.01911-20. [PMID: 33504599 PMCID: PMC8103682 DOI: 10.1128/jvi.01911-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Nef proteins of HIV-1 and SIV enhance viral infectivity by preventing the incorporation of the multipass transmembrane protein serine incorporator 5 (SERINC5), and to a lesser extent SERINC3, into virions. In addition to counteracting SERINCs, SIV Nef also downmodulates several transmembrane proteins from the surface of virus-infected cells, including simian tetherin, CD4 and MHC class I (MHC I) molecules. From a systematic analysis of alanine substitutions throughout the SIVmac239 Nef protein, we identified residues that are required to counteract SERINC5. This information was used to engineer an infectious molecular clone of SIV (SIVmac239nef AV), which differs by two amino acids in the N-terminal domain of Nef that make the virus sensitive to SERINC5 while retaining other activities of Nef. SIVmac239nef AV downmodulates CD3, CD4, MHC I and simian tetherin, but cannot counteract SERINC5. In primary rhesus macaque CD4+ T cells, SIVmac239nef AV exhibits impaired infectivity and replication compared to wild-type SIVmac239. These results demonstrate that SERINC5 antagonism can be separated from other Nef functions and reveal the impact of SERINC5 on lentiviral replication.Importance: SERINC5, a multipass transmembrane protein, is incorporated into retroviral particles during assembly. This leads to a reduction of particle infectivity by inhibiting virus fusion with the target cell membrane. The Nef proteins of HIV-1 and SIV enhance viral infectivity by preventing the incorporation of SERINC5 into virions. However, the relevance of this restriction factor in viral replication has not been elucidated. Here we report a systematic mapping of Nef residues required for SERINC5 antagonism. Counter screens for three other functions of Nef helped identify two residues in the N-terminal domain of Nef, which when mutated make Nef selectively susceptible to SERINC5. Since Nef is multi-functional, genetic separation of SERINC5 antagonism from its other functions affords comparison of the replication of isogenic viruses that are or are not sensitive to SERINC5. Such a strategy revealed the impact of SERINC5 on SIV replication in primary rhesus macaque CD4+ T-cells.
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11
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Kruize Z, van Nuenen AC, van Wijk SW, Girigorie AF, van Dort KA, Booiman T, Kootstra NA. Nef Obtained from Individuals with HIV-1 Vary in Their Ability to Antagonize SERINC3- and SERINC5-Mediated HIV-1 Restriction. Viruses 2021; 13:v13030423. [PMID: 33800773 PMCID: PMC8000780 DOI: 10.3390/v13030423] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 02/25/2021] [Accepted: 03/02/2021] [Indexed: 12/14/2022] Open
Abstract
Nef is a multifunctional viral protein that has the ability to downregulate cell surface molecules, including CD4 and major histocompatibility complex class I (MHC-I) and, as recently shown, also members of the serine incorporator family (SERINC). Here, we analyzed the impact of naturally occurring mutations in HIV-1 Nef on its ability to counteract SERINC restriction and the clinical course of infection. HIV-1 Nef sequences were obtained from 123 participants of the Amsterdam Cohort Studies and showed multiple amino acid variations and mutations. Most of the primary Nef proteins showed increased activity to counteract SERINC3 and SERINC5 as compared to NL4-3 Nef. Several mutations in Nef were associated with either an increased or decreased infectivity of Bal26-pseudotyped HIV-1 produced in the presence of SERINC3 or SERINC5. The 8R, 157N and R178G Nef mutations were shown to have an effect on disease progression. Survival analysis showed an accelerated disease progression of individuals infected with HIV-1 carrying arginine or asparagine at position 8 or 157 in Nef, respectively, or the R178G Nef mutation. Here, we observed that naturally occurring mutations in Nef affect the ability of Nef to counteract SERINC3- and SERINC5-mediated inhibition of viral infectivity. The majority of these Nef mutations had no significant effect on HIV-1 pathogenesis and only the 8R, 157N and R178G mutations were associated with disease course.
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12
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Impaired ability of Nef to counteract SERINC5 is associated with reduced plasma viremia in HIV-infected individuals. Sci Rep 2020; 10:19416. [PMID: 33173092 PMCID: PMC7656250 DOI: 10.1038/s41598-020-76375-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 10/28/2020] [Indexed: 01/23/2023] Open
Abstract
HIV-1 Nef plays an essential role in enhancing virion infectivity by antagonizing the host restriction molecule SERINC5. Because Nef is highly polymorphic due to the selective forces of host cellular immunity, we hypothesized that certain immune-escape polymorphisms may impair Nef’s ability to antagonize SERINC5 and thereby influence viral fitness in vivo. To test this hypothesis, we identified 58 Nef polymorphisms that were overrepresented in HIV-infected patients in Japan sharing the same HLA genotypes. The number of immune-associated Nef polymorphisms was inversely correlated with the plasma viral load. By breaking down the specific HLA allele-associated mutations, we found that a number of the HLA-B*51:01-associated Y120F and Q125H mutations were most significantly associated with a reduced plasma viral load. A series of biochemical experiments showed that the double mutations Y120F/Q125H, but not either single mutation, impaired Nef’s ability to antagonize SERINC5 and was associated with decreasing virion infectivity and viral replication in primary lymphocytes. In contrast, other Nef functions such as CD4, CCR5, CXCR4 and HLA class I downregulation and CD74 upregulation remained unchanged. Taken together, our results suggest that the differential ability of Nef to counteract SERINC5 by naturally occurring immune-associated mutations was associated with the plasma viral load in vivo.
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13
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Staudt RP, Smithgall TE. Nef homodimers down-regulate SERINC5 by AP-2-mediated endocytosis to promote HIV-1 infectivity. J Biol Chem 2020; 295:15540-15552. [PMID: 32873704 DOI: 10.1074/jbc.ra120.014668] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 08/24/2020] [Indexed: 12/13/2022] Open
Abstract
SERINC5 is a multipass intrinsic membrane protein that suppresses HIV-1 infectivity when incorporated into budding virions. The HIV-1 Nef virulence factor prevents viral incorporation of SERINC5 by triggering its down-regulation from the producer cell membrane through an AP-2-dependent endolysosomal pathway. However, the mechanistic basis for SERINC5 down-regulation by Nef remains elusive. Here we demonstrate that Nef homodimers are important for SERINC5 down-regulation, trafficking to late endosomes, and exclusion from newly synthesized viral particles. Based on previous X-ray crystal structures, we mutated three conserved residues in the Nef dimer interface (Leu112, Tyr115, and Phe121) and demonstrated attenuated homodimer formation in a cell-based fluorescence complementation assay. Point mutations at each position reduced the infectivity of HIV-1 produced from transfected 293T cells, the Jurkat TAg T-cell line, and donor mononuclear cells in a SERINC5-dependent manner. In SERINC5-transfected 293T cells, virion incorporation of SERINC5 was increased by dimerization-defective Nef mutants, whereas down-regulation of SERINC5 from the membrane of transfected Jurkat cells by these mutants was significantly reduced. Nef dimer interface mutants also failed to trigger internalization of SERINC5 and localization to Rab7+ late endosomes in T cells. Importantly, fluorescence complementation assays demonstrated that dimerization-defective Nef mutants retained interaction with both SERINC5 and AP-2. These results show that down-regulation of SERINC5 and subsequent enhancement of viral infectivity require Nef homodimers and support a mechanism by which the Nef dimer bridges SERINC5 to AP-2 for endocytosis. Pharmacological disruption of Nef homodimers may control HIV-1 infectivity and viral spread by enhancing virion incorporation of SERINC5.
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Affiliation(s)
- Ryan P Staudt
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Thomas E Smithgall
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, USA.
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14
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Banerjee M, Huang Y, Joshi S, Popa GJ, Mendenhall MD, Wang QJ, Garvy BA, Myint T, Whiteheart SW. Platelets Endocytose Viral Particles and Are Activated via TLR (Toll-Like Receptor) Signaling. Arterioscler Thromb Vasc Biol 2020; 40:1635-1650. [PMID: 32434410 PMCID: PMC7316618 DOI: 10.1161/atvbaha.120.314180] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
OBJECTIVE Thrombocytopenia is associated with many viral infections suggesting virions interact with and affect platelets. Consistently, viral particles are seen inside platelets, and platelet activation markers are detected in viremic patients. In this article, we sought mechanistic insights into these virion/platelet interactions by examining how platelets endocytose, traffic, and are activated by a model virion. Approach and Results: Using fluorescently tagged HIV-1 pseudovirions, 3-dimensional structured illumination microscopy, and transgenic mouse models, we probed the interactions between platelets and virions. Mouse platelets used known endocytic machinery, that is, dynamin, VAMP (vesicle-associated membrane protein)-3, and Arf6 (ADP-ribosylation factor 6), to take up and traffic HIV-1 pseudovirions. Endocytosed HIV-1 pseudovirions trafficked through early (Rab4+) and late endosomes (Rab7+), and then to an LC3+ (microtubule-associated protein 1A/1B-light chain 3) compartment. Incubation with virions induced IRAK4 (interleukin 1 receptor-associated kinase 4), Akt (protein kinase B), and IKK (IκB kinase) activation, granule secretion, and platelet-leukocyte aggregate formation. This activation required TLRs (Toll-like receptors) and MyD88 (myeloid differentiation primary response protein 88) but was less extensive and slower than activation with thrombin. In vivo, HIV-1 pseudovirions injection led to virion uptake and platelet activation, as measured by IKK activation, platelet-leukocyte aggregate formation, and mild thrombocytopenia. All were decreased in VAMP-3-/- and, megakaryocyte/platelet-specific, Arf6-/- mice. Similar platelet activation profiles (increased platelet-leukocyte aggregates, plasma platelet factor 4, and phospho-IκBα) were detected in newly diagnosed and antiretroviral therapy-controlled HIV-1+ patients. CONCLUSIONS Collectively, our data provide mechanistic insights into the cell biology of how platelets endocytose and process virions. We propose a mechanism by which platelets sample the circulation and respond to potential pathogens that they take up.
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Affiliation(s)
- Meenakshi Banerjee
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY
| | - Yunjie Huang
- Division of Pulmonary Medicine, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH
| | - Smita Joshi
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY
- Lexington VA Health Care System, Lexington, KY
| | - Gabriel J. Popa
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY
| | - Michael D. Mendenhall
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY
| | - Qing Jun Wang
- Department of Ophthalmology and Visual Sciences, University of Kentucky, Lexington, KY
| | - Beth A. Garvy
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky, Lexington, KY
| | - Thein Myint
- Department of Infectious Diseases, Bluegrass Care Clinic, Kentucky Clinic, University of Kentucky, Lexington, KY
| | - Sidney W. Whiteheart
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY
- Lexington VA Health Care System, Lexington, KY
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15
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Thippeshappa R, Kimata JT, Kaushal D. Toward a Macaque Model of HIV-1 Infection: Roadblocks, Progress, and Future Strategies. Front Microbiol 2020; 11:882. [PMID: 32477302 PMCID: PMC7237640 DOI: 10.3389/fmicb.2020.00882] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 04/16/2020] [Indexed: 12/15/2022] Open
Abstract
The human-specific tropism of Human Immunodeficiency Virus Type 1 (HIV-1) has complicated the development of a macaque model of HIV-1 infection/AIDS that is suitable for preclinical evaluation of vaccines and novel treatment strategies. Several innate retroviral restriction factors, such as APOBEC3 family of proteins, TRIM5α, BST2, and SAMHD1, that prevent HIV-1 replication have been identified in macaque cells. Accessory proteins expressed by Simian Immunodeficiency virus (SIV) such as viral infectivity factor (Vif), viral protein X (Vpx), viral protein R (Vpr), and negative factor (Nef) have been shown to play key roles in overcoming these restriction factors in macaque cells. Thus, substituting HIV-1 accessory genes with those from SIV may enable HIV-1 replication in macaques. We and others have constructed macaque-tropic HIV-1 derivatives [also called simian-tropic HIV-1 (stHIV-1) or Human-Simian Immunodeficiency Virus (HSIV)] carrying SIV vif to overcome APOBEC3 family proteins. Additional modifications to HIV-1 gag in some of the macaque-tropic HIV-1 have also been done to overcome TRIM5α restriction in rhesus and cynomolgus macaques. Although these viruses replicate persistently in macaque species, they do not result in CD4 depletion. Thus, these studies suggest that additional blocks to HIV-1 replication exist in macaques that prevent high-level viral replication. Furthermore, serial animal-to-animal passaging of macaque-tropic HIV-1 in vivo has not resulted in pathogenic variants that cause AIDS in immunocompetent macaques. In this review, we discuss recent developments made toward developing macaque model of HIV-1 infection.
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Affiliation(s)
- Rajesh Thippeshappa
- Southwest National Primate Research Center, Texas Biomedical Research Institute, San Antonio, TX, United States
| | - Jason T Kimata
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, United States
| | - Deepak Kaushal
- Southwest National Primate Research Center, Texas Biomedical Research Institute, San Antonio, TX, United States
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16
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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.
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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
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17
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Li WF, Aryal M, Shu ST, Smithgall TE. HIV-1 Nef dimers short-circuit immune receptor signaling by activating Tec-family kinases at the host cell membrane. J Biol Chem 2020; 295:5163-5174. [PMID: 32144207 DOI: 10.1074/jbc.ra120.012536] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 03/04/2020] [Indexed: 01/08/2023] Open
Abstract
The HIV-1 virulence factor Nef promotes high-titer viral replication, immune escape, and pathogenicity. Nef interacts with interleukin-2-inducible T-cell kinase (Itk) and Bruton's tyrosine kinase (Btk), two Tec-family kinases expressed in HIV-1 target cells (CD4 T cells and macrophages, respectively). Using a cell-based bimolecular fluorescence complementation assay, here we demonstrate that Nef recruits both Itk and Btk to the cell membrane and induces constitutive kinase activation in transfected 293T cells. Nef homodimerization-defective mutants retained their interaction with both kinases but failed to induce activation, supporting a role for Nef homodimer formation in the activation mechanism. HIV-1 infection up-regulates endogenous Itk activity in SupT1 T cells and donor-derived peripheral blood mononuclear cells. However, HIV-1 strains expressing Nef variants with mutations in the dimerization interface replicated poorly and were significantly attenuated in Itk activation. We conclude that direct activation of Itk and Btk by Nef at the membrane in HIV-infected cells may override normal immune receptor control of Tec-family kinase activity to enhance the viral life cycle.
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Affiliation(s)
- Wing Fai Li
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, Pennsylvania 15219
| | - Manish Aryal
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, Pennsylvania 15219
| | - Sherry T Shu
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, Pennsylvania 15219
| | - Thomas E Smithgall
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, Pennsylvania 15219
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18
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Abstract
The accessory protein Nef of human immunodeficiency virus (HIV) is a primary determinant of viral pathogenesis. Nef is abundantly expressed during infection and reroutes a variety of cell surface proteins to disrupt host immunity and promote the viral replication cycle. Nef counteracts host defenses by sequestering and/or degrading its targets via the endocytic and secretory pathways. Nef does this by physically engaging a number of host trafficking proteins. Substantial progress has been achieved in identifying the targets of Nef, and a structural and mechanistic understanding of Nef's ability to command the protein trafficking machinery has recently started to coalesce. Comparative analysis of HIV and simian immunodeficiency virus (SIV) Nef proteins in the context of recent structural advances sheds further light on both viral evolution and the mechanisms whereby trafficking is hijacked. This review describes how advances in cell and structural biology are uncovering in growing detail how Nef subverts the host immune system, facilitates virus release, and enhances viral infectivity.
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19
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Marrero-Hernández S, Márquez-Arce D, Cabrera-Rodríguez R, Estévez-Herrera J, Pérez-Yanes S, Barroso-González J, Madrid R, Machado JD, Blanco J, Valenzuela-Fernández A. HIV-1 Nef Targets HDAC6 to Assure Viral Production and Virus Infection. Front Microbiol 2019; 10:2437. [PMID: 31736889 PMCID: PMC6831784 DOI: 10.3389/fmicb.2019.02437] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 10/10/2019] [Indexed: 12/11/2022] Open
Abstract
HIV Nef is a central auxiliary protein in HIV infection and pathogenesis. Our results indicate that HDAC6 promotes the aggresome/autophagic degradation of the viral polyprotein Pr55Gag to inhibit HIV-1 production. Nef counteracts this antiviral activity of HDAC6 by inducing its degradation and subsequently stabilizing Pr55Gag and Vif viral proteins. Nef appears to neutralize HDAC6 by an acidic/endosomal-lysosomal processing and does not need the downregulation function, since data obtained with the non-associated cell-surface Nef-G2A mutant - the cytoplasmic location of HDAC6 - together with studies with chemical inhibitors and other Nef mutants, point to this direction. Hence, the polyproline rich region P72xxP75 (69-77 aa) and the di-Leucin motif in the Nef-ExxxLL160-165 sequence of Nef, appear to be responsible for HDAC6 clearance and, therefore, required for this novel Nef proviral function. Nef and Nef-G2A co-immunoprecipitate with HDAC6, whereas the Nef-PPAA mutant showed a reduced interaction with the anti-HIV-1 enzyme. Thus, the P72xxP75 motif appears to be responsible, directly or indirectly, for the interaction of Nef with HDAC6. Remarkably, by neutralizing HDAC6, Nef assures Pr55Gag location and aggregation at plasma membrane, as observed by TIRFM, promotes viral egress, and enhances the infectivity of viral particles. Consequently, our results suggest that HDAC6 acts as an anti-HIV-1 restriction factor, limiting viral production and infection by targeting Pr55Gag and Vif. This function is counteracted by functional HIV-1 Nef, in order to assure viral production and infection capacities. The interplay between HIV-1 Nef and cellular HDAC6 may determine viral infection and pathogenesis, representing both molecules as key targets to battling HIV.
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Affiliation(s)
- Sara Marrero-Hernández
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Medicina, Universidad de La Laguna (ULL), La Laguna, Spain.,Unidad Virología y Microbiología del IUETSPC, Universidad de La Laguna (ULL), La Laguna, Spain
| | - Daniel Márquez-Arce
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Medicina, Universidad de La Laguna (ULL), La Laguna, Spain.,Unidad Virología y Microbiología del IUETSPC, Universidad de La Laguna (ULL), La Laguna, Spain
| | - Romina Cabrera-Rodríguez
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Medicina, Universidad de La Laguna (ULL), La Laguna, Spain.,Unidad Virología y Microbiología del IUETSPC, Universidad de La Laguna (ULL), La Laguna, Spain
| | - Judith Estévez-Herrera
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Medicina, Universidad de La Laguna (ULL), La Laguna, Spain.,Unidad Virología y Microbiología del IUETSPC, Universidad de La Laguna (ULL), La Laguna, Spain
| | - Silvia Pérez-Yanes
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Medicina, Universidad de La Laguna (ULL), La Laguna, Spain.,Unidad Virología y Microbiología del IUETSPC, Universidad de La Laguna (ULL), La Laguna, Spain
| | - Jonathan Barroso-González
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Medicina, Universidad de La Laguna (ULL), La Laguna, Spain
| | - Ricardo Madrid
- BioAssays SL, Campus de Cantoblanco, Madrid, Spain.,Departmento de Genética, Fisiología y Microbiología, Facultad de Biología, Universidad Complutense de Madrid (UCM), Madrid, Spain
| | - José-David Machado
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Medicina, Universidad de La Laguna (ULL), La Laguna, Spain
| | - Julià Blanco
- AIDS Research Institute IrsiCaixa, Institut de Recerca en Ciències de la Salut Germans Trias i Pujol (IGTP), Badalona, Spain.,Universitat de Vic-Central de Catalunya, UVIC-UCC, Catalonia, Spain
| | - Agustín Valenzuela-Fernández
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Medicina, Universidad de La Laguna (ULL), La Laguna, Spain.,Unidad Virología y Microbiología del IUETSPC, Universidad de La Laguna (ULL), La Laguna, Spain
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20
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Ramirez PW, Sharma S, Singh R, Stoneham CA, Vollbrecht T, Guatelli J. Plasma Membrane-Associated Restriction Factors and Their Counteraction by HIV-1 Accessory Proteins. Cells 2019; 8:E1020. [PMID: 31480747 PMCID: PMC6770538 DOI: 10.3390/cells8091020] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 08/29/2019] [Accepted: 08/30/2019] [Indexed: 02/07/2023] Open
Abstract
The plasma membrane is a site of conflict between host defenses and many viruses. One aspect of this conflict is the host's attempt to eliminate infected cells using innate and adaptive cell-mediated immune mechanisms that recognize features of the plasma membrane characteristic of viral infection. Another is the expression of plasma membrane-associated proteins, so-called restriction factors, which inhibit enveloped virions directly. HIV-1 encodes two countermeasures to these host defenses: The membrane-associated accessory proteins Vpu and Nef. In addition to inhibiting cell-mediated immune-surveillance, Vpu and Nef counteract membrane-associated restriction factors. These include BST-2, which traps newly formed virions at the plasma membrane unless counteracted by Vpu, and SERINC5, which decreases the infectivity of virions unless counteracted by Nef. Here we review key features of these two antiviral proteins, and we review Vpu and Nef, which deplete them from the plasma membrane by co-opting specific cellular proteins and pathways of membrane trafficking and protein-degradation. We also discuss other plasma membrane proteins modulated by HIV-1, particularly CD4, which, if not opposed in infected cells by Vpu and Nef, inhibits viral infectivity and increases the sensitivity of the viral envelope glycoprotein to host immunity.
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Affiliation(s)
- Peter W Ramirez
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
- VA San Diego Healthcare System, San Diego, CA 92161, USA
| | - Shilpi Sharma
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
- VA San Diego Healthcare System, San Diego, CA 92161, USA
| | - Rajendra Singh
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
- VA San Diego Healthcare System, San Diego, CA 92161, USA
| | - Charlotte A Stoneham
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
- VA San Diego Healthcare System, San Diego, CA 92161, USA
| | - Thomas Vollbrecht
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
- VA San Diego Healthcare System, San Diego, CA 92161, USA
| | - John Guatelli
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA.
- VA San Diego Healthcare System, San Diego, CA 92161, USA.
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21
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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.
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22
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Firrito C, Bertelli C, Vanzo T, Chande A, Pizzato M. SERINC5 as a New Restriction Factor for Human Immunodeficiency Virus and Murine Leukemia Virus. Annu Rev Virol 2019; 5:323-340. [PMID: 30265629 DOI: 10.1146/annurev-virology-092917-043308] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
SERINC genes encode for homologous multipass transmembrane proteins with unknown cellular function, despite being highly conserved across eukaryotes. Among the five SERINC genes found in humans, SERINC5 was shown to act as a powerful inhibitor of retroviruses. It is efficiently incorporated into virions and blocks the penetration of the viral core into target cells, by impairing the fusion process with a yet unclear mechanism. SERINC5 was also found to promote human immunodeficiency virus 1 (HIV-1) virion neutralization by antibodies, indicating a pleiotropic activity, which remains mostly unexplored. Counteracting factors have emerged independently in at least three retrovirus lineages, underscoring their fundamental importance during retrovirus evolution. Nef and S2 of primate and equine lentiviruses, and glycoGag of gammaretroviruses, act similarly by targeting SERINC5 to endosomes and excluding it from virions. Here, we discuss the features that distinguish SERINC5 from other known restriction factors, delineating a yet unique class of antiviral inhibitors.
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Affiliation(s)
- Claudia Firrito
- Centre for Integrative Biology, University of Trento, 38123 Trento, Italy ; , , ,
| | - Cinzia Bertelli
- Centre for Integrative Biology, University of Trento, 38123 Trento, Italy ; , , ,
| | - Teresa Vanzo
- Centre for Integrative Biology, University of Trento, 38123 Trento, Italy ; , , ,
| | - Ajit Chande
- Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal, Bhopal 462 066, Madhya Pradesh, India;
| | - Massimo Pizzato
- Centre for Integrative Biology, University of Trento, 38123 Trento, Italy ; , , ,
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23
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TIM-mediated inhibition of HIV-1 release is antagonized by Nef but potentiated by SERINC proteins. Proc Natl Acad Sci U S A 2019; 116:5705-5714. [PMID: 30842281 DOI: 10.1073/pnas.1819475116] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The T cell Ig and mucin domain (TIM) proteins inhibit release of HIV-1 and other enveloped viruses by interacting with cell- and virion-associated phosphatidylserine (PS). Here, we show that the Nef proteins of HIV-1 and other lentiviruses antagonize TIM-mediated restriction. TIM-1 more potently inhibits the release of Nef-deficient relative to Nef-expressing HIV-1, and ectopic expression of Nef relieves restriction. HIV-1 Nef does not down-regulate the overall level of TIM-1 expression, but promotes its internalization from the plasma membrane and sequesters its expression in intracellular compartments. Notably, Nef mutants defective in modulating membrane protein endocytic trafficking are incapable of antagonizing TIM-mediated inhibition of HIV-1 release. Intriguingly, depletion of SERINC3 or SERINC5 proteins in human peripheral blood mononuclear cells (PBMCs) attenuates TIM-1 restriction of HIV-1 release, in particular that of Nef-deficient viruses. In contrast, coexpression of SERINC3 or SERINC5 increases the expression of TIM-1 on the plasma membrane and potentiates TIM-mediated inhibition of HIV-1 production. Pulse-chase metabolic labeling reveals that the half-life of TIM-1 is extended by SERINC5 from <2 to ∼6 hours, suggesting that SERINC5 stabilizes the expression of TIM-1. Consistent with a role for SERINC protein in potentiating TIM-1 restriction, we find that MLV glycoGag and EIAV S2 proteins, which, like Nef, antagonize SERINC-mediated diminishment of HIV-1 infectivity, also effectively counteract TIM-mediated inhibition of HIV-1 release. Collectively, our work reveals a role of Nef in antagonizing TIM-1 and highlights the complex interplay between Nef and HIV-1 restriction by TIMs and SERINCs.
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24
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de Sousa-Pereira P, Abrantes J, Bauernfried S, Pierini V, Esteves PJ, Keppler OT, Pizzato M, Hornung V, Fackler OT, Baldauf HM. The antiviral activity of rodent and lagomorph SERINC3 and SERINC5 is counteracted by known viral antagonists. J Gen Virol 2018; 100:278-288. [PMID: 30566072 DOI: 10.1099/jgv.0.001201] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A first step towards the development of a human immunodeficiency virus (HIV) animal model has been the identification and surmounting of species-specific barriers encountered by HIV along its replication cycle in cells from small animals. Serine incorporator proteins 3 (SERINC3) and 5 (SERINC5) were recently identified as restriction factors that reduce HIV-1 infectivity. Here, we compared the antiviral activity of SERINC3 and SERINC5 among mice, rats and rabbits, and their susceptibility to viral counteraction to their human counterparts. In the absence of viral antagonists, rodent and lagomorph SERINC3 and SERINC5 displayed anti-HIV activity in a similar range to human controls. Vesicular stomatitis virus G protein (VSV-G) pseudotyped virions were considerably less sensitive to restriction by all SERINC3/5 orthologs. Interestingly, HIV-1 Nef, murine leukemia virus (MLV) GlycoGag and equine infectious anemia virus (EIAV) S2 counteracted the antiviral activity of all SERINC3/5 orthologs with similar efficiency. Our results demonstrate that the antiviral activity of SERINC3/5 proteins is conserved in rodents and rabbits, and can be overcome by all three previously reported viral antagonists.
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Affiliation(s)
- Patrícia de Sousa-Pereira
- 3Institute of Medical Virology, University Hospital Frankfurt, Frankfurt, Germany.,1CIBIO/InBIO- Research Network in Biodiversity and Evolutionary Biology, Campus de Vairão, University of Porto, Vairão, Portugal.,5Institute of Virology, Technische Universität München/Helmholtz Zentrum, Munich, Germany.,4Max von Pettenkofer Institute & Gene Center, Virology, National Reference Center for Retroviruses, Faculty of Medicine, LMU München, Munich, Germany.,2Department of Biology, Faculty of Sciences, University of Porto, Porto, Portugal
| | - Joana Abrantes
- 1CIBIO/InBIO- Research Network in Biodiversity and Evolutionary Biology, Campus de Vairão, University of Porto, Vairão, Portugal
| | - Stefan Bauernfried
- 6Gene Center and Department of Biochemistry, LMU München, Munich, Germany
| | - Virginia Pierini
- 7Department of Infectious Diseases, Integrative Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Pedro José Esteves
- 1CIBIO/InBIO- Research Network in Biodiversity and Evolutionary Biology, Campus de Vairão, University of Porto, Vairão, Portugal.,2Department of Biology, Faculty of Sciences, University of Porto, Porto, Portugal.,8CITS - Centro de Investigação em Tecnologias de Saúde, CESPU, Gandra, Portugal
| | - Oliver T Keppler
- 3Institute of Medical Virology, University Hospital Frankfurt, Frankfurt, Germany.,4Max von Pettenkofer Institute & Gene Center, Virology, National Reference Center for Retroviruses, Faculty of Medicine, LMU München, Munich, Germany.,5Institute of Virology, Technische Universität München/Helmholtz Zentrum, Munich, Germany
| | - Massimo Pizzato
- 9University of Trento, Centre for Integrative Biology, Trento, Italy
| | - Veit Hornung
- 6Gene Center and Department of Biochemistry, LMU München, Munich, Germany
| | - Oliver T Fackler
- 7Department of Infectious Diseases, Integrative Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Hanna-Mari Baldauf
- 5Institute of Virology, Technische Universität München/Helmholtz Zentrum, Munich, Germany.,3Institute of Medical Virology, University Hospital Frankfurt, Frankfurt, Germany.,4Max von Pettenkofer Institute & Gene Center, Virology, National Reference Center for Retroviruses, Faculty of Medicine, LMU München, Munich, Germany
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25
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Abstract
The p2b domain of Rous sarcoma virus (RSV) Gag and the p6 domain of HIV-1 Gag contain late assembly (L) domains that engage the ESCRT membrane fission machinery and are essential for virus release. We now show that the PPXY-type RSV L domain specifically recruits the BAR domain protein PACSIN2 into virus-like particles (VLP), in addition to the NEDD4-like ubiquitin ligase ITCH and ESCRT pathway components such as TSG101. PACSIN2, which has been implicated in the remodeling of cellular membranes and the actin cytoskeleton, is also recruited by HIV-1 p6 independent of its ability to engage the ESCRT factors TSG101 or ALIX. Moreover, PACSIN2 is robustly recruited by NEDD4-2s, a NEDD4-like ubiquitin ligase capable of rescuing HIV-1 budding defects. The NEDD4-2s-induced incorporation of PACSIN2 into VLP correlated with the formation of Gag-ubiquitin conjugates, indicating that PACSIN2 binds ubiquitin. Although PACSIN2 was not required for a single cycle of HIV-1 replication after infection with cell-free virus, HIV-1 spreading was nevertheless severely impaired in T cell lines and primary human peripheral blood mononuclear cells depleted of PACSIN2. HIV-1 spreading could be restored by reintroduction of wild-type PACSIN2, but not of a SH3 domain mutant unable to interact with the actin polymerization regulators WASP and N-WASP. Overall, our observations indicate that PACSIN2 promotes the cell-to-cell spreading of HIV-1 by connecting Gag to the actin cytoskeleton.
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26
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Shi J, Xiong R, Zhou T, Su P, Zhang X, Qiu X, Li H, Li S, Yu C, Wang B, Ding C, Smithgall TE, Zheng YH. HIV-1 Nef Antagonizes SERINC5 Restriction by Downregulation of SERINC5 via the Endosome/Lysosome System. J Virol 2018; 92:e00196-18. [PMID: 29514909 PMCID: PMC5952139 DOI: 10.1128/jvi.00196-18] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 03/01/2018] [Indexed: 12/11/2022] Open
Abstract
The primate lentiviral accessory protein Nef downregulates CD4 and major histocompatibility complex class I (MHC-I) from the cell surface via independent endosomal trafficking pathways to promote viral pathogenesis. In addition, Nef antagonizes a novel restriction factor, SERINC5 (Ser5), to increase viral infectivity. To explore the molecular mechanism of Ser5 antagonism by Nef, we determined how Nef affects Ser5 expression and intracellular trafficking in comparison to CD4 and MHC-I. We confirm that Nef excludes Ser5 from human immunodeficiency virus type 1 (HIV-1) virions by downregulating its cell surface expression via similar functional motifs required for CD4 downregulation. We find that Nef decreases both Ser5 and CD4 expression at steady-state levels, which are rescued by NH4Cl or bafilomycin A1 treatment. Nef binding to Ser5 was detected in living cells using a bimolecular fluorescence complementation assay, where Nef membrane association is required for interaction. In addition, Nef triggers rapid Ser5 internalization via receptor-mediated endocytosis and relocalizes Ser5 to Rab5+ early, Rab7+ late, and Rab11+ recycling endosomes. Manipulation of AP-2, Rab5, Rab7, and Rab11 expression levels affects the Nef-dependent Ser5 and CD4 downregulation. Moreover, although Nef does not promote Ser5 polyubiquitination, Ser5 downregulation relies on the ubiquitination pathway, and both K48- and K63-specific ubiquitin linkages are required for the downregulation. Finally, Nef promotes Ser5 colocalization with LAMP1, which is enhanced by bafilomycin A1 treatment, suggesting that Ser5 is targeted to lysosomes for destruction. We conclude that Nef uses a similar mechanism to downregulate Ser5 and CD4, which sorts Ser5 into a point-of-no-return degradative pathway to counteract its restriction.IMPORTANCE Human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) express an accessory protein called Nef to promote viral pathogenesis. Nef drives immune escape in vivo through downregulation of CD4 and MHC-I from the host cell surface. Recently, Nef was reported to counteract a novel host restriction factor, Ser5, to increase viral infectivity. Nef downregulates cell surface Ser5, thus preventing its incorporation into virus particles, resulting in disruption of its antiviral activity. Here, we report mechanistic studies of Nef-mediated Ser5 downregulation in comparison to CD4 and MHC-I. We demonstrate that Nef binds directly to Ser5 in living cells and that Nef-Ser5 interaction requires Nef association with the plasma membrane. Subsequently, Nef internalizes Ser5 from the plasma membrane via receptor-mediated endocytosis, and targets ubiquitinated Ser5 to endosomes and lysosomes for destruction. Collectively, these results provide new insights into our ongoing understanding of the Nef-Ser5 arms race in HIV-1 infection.
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Affiliation(s)
- Jing Shi
- Harbin Veterinary Research Institute, CAAS-Michigan State University Joint Laboratory of Innate Immunity, State Key Laboratory of Veterinary Biotechnology, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Ran Xiong
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Tao Zhou
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Peiyi Su
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Xihe Zhang
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Xusheng Qiu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Hongmei Li
- Department of Pathology, Qiqihar Medical University, Qiqihar, China
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Sunan Li
- Harbin Veterinary Research Institute, CAAS-Michigan State University Joint Laboratory of Innate Immunity, State Key Laboratory of Veterinary Biotechnology, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Changqing Yu
- Harbin Veterinary Research Institute, CAAS-Michigan State University Joint Laboratory of Innate Immunity, State Key Laboratory of Veterinary Biotechnology, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Bin Wang
- Harbin Veterinary Research Institute, CAAS-Michigan State University Joint Laboratory of Innate Immunity, State Key Laboratory of Veterinary Biotechnology, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Chan Ding
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Thomas E Smithgall
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Yong-Hui Zheng
- Harbin Veterinary Research Institute, CAAS-Michigan State University Joint Laboratory of Innate Immunity, State Key Laboratory of Veterinary Biotechnology, Chinese Academy of Agricultural Sciences, Harbin, China
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
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27
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Compeer EB, Kraus F, Ecker M, Redpath G, Amiezer M, Rother N, Nicovich PR, Kapoor-Kaushik N, Deng Q, Samson GPB, Yang Z, Lou J, Carnell M, Vartoukian H, Gaus K, Rossy J. A mobile endocytic network connects clathrin-independent receptor endocytosis to recycling and promotes T cell activation. Nat Commun 2018; 9:1597. [PMID: 29686427 PMCID: PMC5913236 DOI: 10.1038/s41467-018-04088-w] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 04/03/2018] [Indexed: 01/17/2023] Open
Abstract
Endocytosis of surface receptors and their polarized recycling back to the plasma membrane are central to many cellular processes, such as cell migration, cytokinesis, basolateral polarity of epithelial cells and T cell activation. Little is known about the mechanisms that control the organization of recycling endosomes and how they connect to receptor endocytosis. Here, we follow the endocytic journey of the T cell receptor (TCR), from internalization at the plasma membrane to recycling back to the immunological synapse. We show that TCR triggering leads to its rapid uptake through a clathrin-independent pathway. Immediately after internalization, TCR is incorporated into a mobile and long-lived endocytic network demarked by the membrane-organizing proteins flotillins. Although flotillins are not required for TCR internalization, they are necessary for its recycling to the immunological synapse. We further show that flotillins are essential for T cell activation, supporting TCR nanoscale organization and signaling.
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Affiliation(s)
- Ewoud B Compeer
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences and the ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, High St Gate 9, Sydney, NSW, 2052, Australia
- Kennedy Institute of Rheumatology, University of Oxford, Roosevelt Drive, Headington, Oxford, OX3 7FY, UK
| | - Felix Kraus
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences and the ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, High St Gate 9, Sydney, NSW, 2052, Australia
- Department of Biochemistry and Molecular Biology, Monash University, 23 Innovation Walk, Melbourne, VIC, 3800, Australia
| | - Manuela Ecker
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences and the ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, High St Gate 9, Sydney, NSW, 2052, Australia
| | - Gregory Redpath
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences and the ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, High St Gate 9, Sydney, NSW, 2052, Australia
| | - Mayan Amiezer
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences and the ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, High St Gate 9, Sydney, NSW, 2052, Australia
- The Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW, 2010, Australia
| | - Nils Rother
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences and the ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, High St Gate 9, Sydney, NSW, 2052, Australia
- Department of Nephrology, Radboud University Medical Center, Geert Grooteplein 10, 6525, GA, Nijmegen, The Netherlands
| | - Philip R Nicovich
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences and the ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, High St Gate 9, Sydney, NSW, 2052, Australia
| | - Natasha Kapoor-Kaushik
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences and the ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, High St Gate 9, Sydney, NSW, 2052, Australia
| | - Qiji Deng
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences and the ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, High St Gate 9, Sydney, NSW, 2052, Australia
| | - Guerric P B Samson
- Biotechnology Institute Thurgau at the University of Konstanz, 8280, Kreuzlingen, Switzerland
| | - Zhengmin Yang
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences and the ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, High St Gate 9, Sydney, NSW, 2052, Australia
| | - Jieqiong Lou
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences and the ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, High St Gate 9, Sydney, NSW, 2052, Australia
| | - Michael Carnell
- Biomedical Imaging Facility, University of New South Wales, High St Gate 9, Sydney, NSW, 2052, Australia
| | - Haig Vartoukian
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences and the ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, High St Gate 9, Sydney, NSW, 2052, Australia
| | - Katharina Gaus
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences and the ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, High St Gate 9, Sydney, NSW, 2052, Australia
| | - Jérémie Rossy
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences and the ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, High St Gate 9, Sydney, NSW, 2052, Australia.
- Biotechnology Institute Thurgau at the University of Konstanz, 8280, Kreuzlingen, Switzerland.
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28
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Dai W, Usami Y, Wu Y, Göttlinger H. A Long Cytoplasmic Loop Governs the Sensitivity of the Anti-viral Host Protein SERINC5 to HIV-1 Nef. Cell Rep 2018; 22:869-875. [PMID: 29386131 PMCID: PMC5810964 DOI: 10.1016/j.celrep.2017.12.082] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 12/05/2017] [Accepted: 12/22/2017] [Indexed: 12/14/2022] Open
Abstract
We recently identified the multipass transmembrane protein SERINC5 as an antiviral protein that can potently inhibit HIV-1 infectivity and is counteracted by HIV-1 Nef. We now report that the anti-HIV-1 activity, but not the sensitivity to Nef, is conserved among vertebrate SERINC5 proteins. However, a Nef-resistant SERINC5 became Nef sensitive when its intracellular loop 4 (ICL4) was replaced by that of Nef-sensitive human SERINC5. Conversely, human SERINC5 became resistant to Nef when its ICL4 was replaced by that of a Nef-resistant SERINC5. In general, ICL4 regions from SERINCs that exhibited resistance to a given Nef conferred resistance to the same Nef when transferred to a sensitive SERINC, and vice versa. Our results establish that human SERINC5 can be modified to restrict HIV-1 infectivity even in the presence of Nef.
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Affiliation(s)
- Weiwei Dai
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Yoshiko Usami
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Yuanfei Wu
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Heinrich Göttlinger
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
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29
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Foster TL, Pickering S, Neil SJD. Inhibiting the Ins and Outs of HIV Replication: Cell-Intrinsic Antiretroviral Restrictions at the Plasma Membrane. Front Immunol 2018; 8:1853. [PMID: 29354117 PMCID: PMC5758531 DOI: 10.3389/fimmu.2017.01853] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 12/07/2017] [Indexed: 01/01/2023] Open
Abstract
Like all viruses, human immunodeficiency viruses (HIVs) and their primate lentivirus relatives must enter cells in order to replicate and, once produced, new virions need to exit to spread to new targets. These processes require the virus to cross the plasma membrane of the cell twice: once via fusion mediated by the envelope glycoprotein to deliver the viral core into the cytosol; and secondly by ESCRT-mediated scission of budding virions during release. This physical barrier thus presents a perfect location for host antiviral restrictions that target enveloped viruses in general. In this review we will examine the current understanding of innate host antiviral defences that inhibit these essential replicative steps of primate lentiviruses associated with the plasma membrane, the mechanism by which these viruses have adapted to evade such defences, and the role that this virus/host battleground plays in the transmission and pathogenesis of HIV/AIDS.
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Affiliation(s)
- Toshana L Foster
- Department of Infectious Disease, School of Immunology and Microbial Sciences, King's College London, London, United Kingdom
| | - Suzanne Pickering
- Department of Infectious Disease, School of Immunology and Microbial Sciences, King's College London, London, United Kingdom
| | - Stuart J D Neil
- Department of Infectious Disease, School of Immunology and Microbial Sciences, King's College London, London, United Kingdom
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30
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HIV Activates the Tyrosine Kinase Hck to Secrete ADAM Protease-Containing Extracellular Vesicles. EBioMedicine 2018; 28:151-161. [PMID: 29331674 PMCID: PMC5836510 DOI: 10.1016/j.ebiom.2018.01.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 12/13/2017] [Accepted: 01/03/2018] [Indexed: 11/21/2022] Open
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31
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SERINC as a Restriction Factor to Inhibit Viral Infectivity and the Interaction with HIV. J Immunol Res 2017; 2017:1548905. [PMID: 29359168 PMCID: PMC5735641 DOI: 10.1155/2017/1548905] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 10/22/2017] [Accepted: 11/02/2017] [Indexed: 12/16/2022] Open
Abstract
The serine incorporator 5 (SERINC5) is a recently discovered restriction factor that inhibits viral infectivity by preventing fusion. Retroviruses have developed strategies to counteract the action of SERINC5, such as the expression of proteins like negative regulatory factor (Nef), S2, and glycosylated Gag (glycoGag). These accessory proteins downregulate SERINC5 from the plasma membrane for subsequent degradation in the lysosomes. The observed variability in the action of SERINC5 suggests the participation of other elements like the envelope glycoprotein (Env) that modulates susceptibility of the virus towards SERINC5. The exact mechanism by which SERINC5 inhibits viral fusion has not yet been determined, although it has been proposed that it increases the sensitivity of the Env by exposing regions which are recognized by neutralizing antibodies. More studies are needed to understand the role of SERINC5 and to assess its utility as a therapeutic strategy.
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32
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Jakobsdottir GM, Iliopoulou M, Nolan R, Alvarez L, Compton AA, Padilla-Parra S. On the Whereabouts of HIV-1 Cellular Entry and Its Fusion Ports. Trends Mol Med 2017; 23:932-944. [PMID: 28899754 DOI: 10.1016/j.molmed.2017.08.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 08/12/2017] [Accepted: 08/14/2017] [Indexed: 01/06/2023]
Abstract
HIV-1 disseminates to diverse tissues through different cell types and establishes long-lived reservoirs. The exact cellular compartment where fusion occurs differs depending on the cell type and mode of viral transmission. This implies that HIV-1 may modulate a number of common host cell factors in different cell types. In this review, we evaluate recent advances on the host cell factors that play an important role in HIV-1 entry and fusion. New insights from restriction factors inhibiting virus-cell fusion in vitro may contribute to the development of future therapeutic interventions. Collectively, novel findings underline the need for potent, host-directed therapies that disrupt the earliest stages of the virus life cycle and preclude the emergence of resistant viral variants.
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Affiliation(s)
- G Maria Jakobsdottir
- Wellcome Trust Centre for Human Genetics, Cellular Imaging, University of Oxford, Oxford, UK
| | - Maro Iliopoulou
- Wellcome Trust Centre for Human Genetics, Cellular Imaging, University of Oxford, Oxford, UK
| | - Rory Nolan
- Wellcome Trust Centre for Human Genetics, Cellular Imaging, University of Oxford, Oxford, UK
| | - Luis Alvarez
- Wellcome Trust Centre for Human Genetics, Cellular Imaging, University of Oxford, Oxford, UK
| | - Alex A Compton
- HIV Dynamics and Replication Program, National Cancer Institute, Frederick, MD 21702, USA
| | - Sergi Padilla-Parra
- Wellcome Trust Centre for Human Genetics, Cellular Imaging, University of Oxford, Oxford, UK; Division of Structural Biology, University of Oxford,The Henry Wellcome Building for Genomic Medicine, Headington, Oxford OX3 7BN, UK.
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33
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Trautz B, Wiedemann H, Lüchtenborg C, Pierini V, Kranich J, Glass B, Kräusslich HG, Brocker T, Pizzato M, Ruggieri A, Brügger B, Fackler OT. The host-cell restriction factor SERINC5 restricts HIV-1 infectivity without altering the lipid composition and organization of viral particles. J Biol Chem 2017; 292:13702-13713. [PMID: 28659343 DOI: 10.1074/jbc.m117.797332] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 06/21/2017] [Indexed: 12/14/2022] Open
Abstract
The host-cell restriction factor SERINC5 potently suppresses the infectivity of HIV, type 1 (HIV-1) particles, and is counteracted by the viral pathogenesis factor Nef. However, the molecular mechanism by which SERINC5 restricts HIV-1 particle infectivity is still unclear. Because SERINC proteins have been suggested to facilitate the incorporation of serine during the biosynthesis of membrane lipids and because lipid composition of HIV particles is a major determinant of the infectious potential of the particles, we tested whether SERINC5-mediated restriction of HIV particle infectivity involves alterations of membrane lipid composition. We produced and purified HIV-1 particles from SERINC5293T cells with very low endogenous SERINC5 levels under conditions in which ectopically expressed SERINC5 restricts HIV-1 infectivity and is antagonized by Nef and analyzed both virions and producer cells with quantitative lipid MS. SERINC5 restriction and Nef antagonism were not associated with significant alterations in steady-state lipid composition of producer cells and HIV particles. Sphingosine metabolism kinetics were also unaltered by SERINC5 expression. Moreover, the levels of phosphatidylserine on the surface of HIV-1 particles, which may trigger uptake into non-productive internalization pathways in target cells, did not change upon expression of SERINC5 or Nef. Finally, saturating the phosphatidylserine-binding sites on HIV target cells did not affect SERINC5 restriction or Nef antagonism. These results demonstrate that the restriction of HIV-1 particle infectivity by SERINC5 does not depend on alterations in lipid composition and organization of HIV-1 particles and suggest that channeling serine into lipid biosynthesis may not be a cardinal cellular function of SERINC5.
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Affiliation(s)
- Birthe Trautz
- From the Department of Infectious Diseases, Integrative Virology, and
| | - Hannah Wiedemann
- the Heidelberg University Biochemistry Center, INF 328, 69120 Heidelberg, Germany
| | | | - Virginia Pierini
- From the Department of Infectious Diseases, Integrative Virology, and
| | - Jan Kranich
- the Institute for Immunology, Ludwig-Maximilians-Universität München, Groβhardener Straße 9, 82152 Planegg-Martinsried, Germany
| | - Bärbel Glass
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, INF 324, 69120 Heidelberg, Germany
| | - Hans-Georg Kräusslich
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, INF 324, 69120 Heidelberg, Germany
| | - Thomas Brocker
- the Institute for Immunology, Ludwig-Maximilians-Universität München, Groβhardener Straße 9, 82152 Planegg-Martinsried, Germany
| | - Massimo Pizzato
- the University of Trento, Centre for Integrative Biology, 38122 Trento, Italy, and
| | - Alessia Ruggieri
- the Department of Infectious Diseases, Molecular Virology, University Hospital Heidelberg, INF 345, 69120 Heidelberg, Germany
| | - Britta Brügger
- the Heidelberg University Biochemistry Center, INF 328, 69120 Heidelberg, Germany,
| | - Oliver T Fackler
- From the Department of Infectious Diseases, Integrative Virology, and
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Serena M, Parolini F, Biswas P, Sironi F, Blanco Miranda A, Zoratti E, Scupoli MT, Ziglio S, Valenzuela-Fernandez A, Gibellini D, Romanelli MG, Siccardi A, Malnati M, Beretta A, Zipeto D. HIV-1 Env associates with HLA-C free-chains at the cell membrane modulating viral infectivity. Sci Rep 2017; 7:40037. [PMID: 28051183 PMCID: PMC5209703 DOI: 10.1038/srep40037] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 11/30/2016] [Indexed: 12/13/2022] Open
Abstract
HLA-C has been demonstrated to associate with HIV-1 envelope glycoprotein (Env). Virions lacking HLA-C have reduced infectivity and increased susceptibility to neutralizing antibodies. Like all others MHC-I molecules, HLA-C requires β2-microglobulin (β2m) for appropriate folding and expression on the cell membrane but this association is weaker, thus generating HLA-C free-chains on the cell surface. In this study, we deepen the understanding of HLA-C and Env association by showing that HIV-1 specifically increases the amount of HLA-C free chains, not bound to β2m, on the membrane of infected cells. The association between Env and HLA-C takes place at the cell membrane requiring β2m to occur. We report that the enhanced infectivity conferred to HIV-1 by HLA-C specifically involves HLA-C free chain molecules that have been correctly assembled with β2m. HIV-1 Env-pseudotyped viruses produced in the absence of β2m are less infectious than those produced in the presence of β2m. We hypothesize that the conformation and surface expression of HLA-C molecules could be a discriminant for the association with Env. Binding stability to β2m may confer to HLA-C the ability to preferentially act either as a conventional immune-competent molecule or as an accessory molecule involved in HIV-1 infectivity.
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Affiliation(s)
- Michela Serena
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Strada le Grazie 8, 37134, Verona, Italy
| | - Francesca Parolini
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Strada le Grazie 8, 37134, Verona, Italy
| | - Priscilla Biswas
- IRCCS Ospedale San Raffaele, Via Olgettina 60, 20132, Milan, Italy
| | - Francesca Sironi
- IRCCS Ospedale San Raffaele, Via Olgettina 60, 20132, Milan, Italy
| | - Almudena Blanco Miranda
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Strada le Grazie 8, 37134, Verona, Italy
| | - Elisa Zoratti
- University Laboratory of Medical Research, Piazzale L. A. Scuro 10, 37134 Verona, Italy
| | - Maria Teresa Scupoli
- University Laboratory of Medical Research, Piazzale L. A. Scuro 10, 37134 Verona, Italy
| | - Serena Ziglio
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Strada le Grazie 8, 37134, Verona, Italy.,Laboratorio de Inmunología Celular y Viral, Unidad de Virología IUETSPC, Unidad de Farmacología, Sección de Medicina, Facultad de Ciencias de la Salud, Universidad de La Laguna (ULL), Campus de Ofra s/n, 38071, Tenerife, Spain
| | - Agustin Valenzuela-Fernandez
- Laboratorio de Inmunología Celular y Viral, Unidad de Virología IUETSPC, Unidad de Farmacología, Sección de Medicina, Facultad de Ciencias de la Salud, Universidad de La Laguna (ULL), Campus de Ofra s/n, 38071, Tenerife, Spain
| | - Davide Gibellini
- Department of Diagnostics and Public Health, University of Verona, Strada le Grazie 8, 37134, Verona, Italy
| | - Maria Grazia Romanelli
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Strada le Grazie 8, 37134, Verona, Italy
| | - Antonio Siccardi
- IRCCS Ospedale San Raffaele, Via Olgettina 60, 20132, Milan, Italy
| | - Mauro Malnati
- IRCCS Ospedale San Raffaele, Via Olgettina 60, 20132, Milan, Italy
| | - Alberto Beretta
- IRCCS Ospedale San Raffaele, Via Olgettina 60, 20132, Milan, Italy
| | - Donato Zipeto
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Strada le Grazie 8, 37134, Verona, Italy
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The Antagonism of HIV-1 Nef to SERINC5 Particle Infectivity Restriction Involves the Counteraction of Virion-Associated Pools of the Restriction Factor. J Virol 2016; 90:10915-10927. [PMID: 27681140 DOI: 10.1128/jvi.01246-16] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 09/21/2016] [Indexed: 11/20/2022] Open
Abstract
SERINC3 (serine incorporator 3) and SERINC5 are recently identified host cell inhibitors of HIV-1 particle infectivity that are counteracted by the viral pathogenesis factor Nef. Here we confirm that HIV-1 Nef, but not HIV-1 Vpu, antagonizes the particle infectivity restriction of SERINC5. SERINC5 antagonism occurred in parallel with other Nef activities, including cell surface receptor downregulation, trans-Golgi network targeting of Lck, and inhibition of host cell actin dynamics. Interaction motifs with host cell endocytic machinery and the Nef-associated kinase complex, as well as CD4 cytoplasmic tail/HIV-1 protease, were identified as essential Nef determinants for SERINC5 antagonism. Characterization of antagonism-deficient Nef mutants revealed that counteraction of SERINC5 occurs in the absence of retargeting of the restriction factor to intracellular compartments and reduction of SERINC5 cell surface density is insufficient for antagonism. Consistent with virion incorporation of SERINC5 being a prerequisite for its antiviral activity, the infectivity of HIV-1 particles produced in the absence of a SERINC5 antagonist decreased with increasing amounts of virion SERINC5. At low levels of SERINC5 expression, enhancement of virion infectivity by Nef was associated with reduced virion incorporation of SERINC5 and antagonism-defective Nef mutants failed to exclude SERINC5 from virions. However, at elevated levels of SERINC5 expression, Nef maintained infectious HIV particles, despite significant virion incorporation of the restriction factor. These results suggest that in addition to virion exclusion, Nef employs a cryptic mechanism to antagonize virion-associated SERINC5. The involvement of common determinants suggests that the antagonism of Nef to SERINC5 and the downregulation of cell surface CD4 by Nef involve related molecular mechanisms. IMPORTANCE HIV-1 Nef critically determines virus spread and disease progression in infected individuals by incompletely defined mechanisms. SERINC3 and SERINC5 were recently identified as potent inhibitors of HIV particle infectivity whose antiviral activity is antagonized by HIV-1 Nef. To address the mechanism of SERINC5 antagonism, we identified four molecular determinants of Nef antagonism that are all linked to the mechanism by which Nef downregulates cell surface CD4. Functional characterization of these mutants revealed that endosomal targeting and cell surface downregulation of SERINC5 are dispensable and insufficient for antagonism, respectively. In contrast, virion exclusion and antagonism of SERINC5 were correlated; however, Nef was also able to enhance the infectivity of virions that incorporated robust levels of SERINC5. These results suggest that the antagonism of HIV-1 Nef to SERINC5 restriction of virion infectivity is mediated by a dual mechanism that is related to CD4 downregulation.
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36
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S2 from equine infectious anemia virus is an infectivity factor which counteracts the retroviral inhibitors SERINC5 and SERINC3. Proc Natl Acad Sci U S A 2016; 113:13197-13202. [PMID: 27803322 DOI: 10.1073/pnas.1612044113] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The lentivirus equine infectious anemia virus (EIAV) encodes the small protein S2, a pathogenic determinant that is important for virus replication and disease progression in horses. No molecular function had been linked to this accessory protein. We report that S2 can replace the activity of Negative factor (Nef) in HIV-1 infectivity, being required to antagonize the inhibitory activity of Serine incorporator (SERINC) proteins on Nef-defective HIV-1. Like Nef, S2 excludes SERINC5 from virus particles and requires an ExxxLL motif predicted to recruit the clathrin adaptor, Adaptor protein 2 (AP2). Accordingly, functional endocytic machinery is essential for S2-mediated infectivity enhancement, and S2-mediated enhancement is impaired by inhibitors of clathrin-mediated endocytosis. In addition to retargeting SERINC5 to a late endosomal compartment, S2 promotes host factor degradation. Emphasizing the similarity with Nef, we show that S2 is myristoylated, and, as is compatible with a crucial role in posttranslational modification, its N-terminal glycine is required for anti-SERINC5 activity. EIAV-derived vectors devoid of S2 are less susceptible than HIV-1 to the inhibitory effect of both human and equine SERINC5. We then identified the envelope glycoprotein of EIAV as a determinant that also modulates retroviral susceptibility to SERINC5, indicating that EIAV has a bimodal ability to counteract the host factor. S2 shares no sequence homology with other retroviral factors known to counteract SERINC5. Like the primate lentivirus Nef and the gammaretrovirus glycoGag, the accessory protein from EIAV is an example of a retroviral virulence determinant that independently evolved SERINC5-antagonizing activity. SERINC5 therefore plays a critical role in the interaction of the host with diverse retrovirus pathogens.
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37
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Redgrove KA, Bernstein IR, Pye VJ, Mihalas BP, Sutherland JM, Nixon B, McCluskey A, Robinson PJ, Holt JE, McLaughlin EA. Dynamin 2 is essential for mammalian spermatogenesis. Sci Rep 2016; 6:35084. [PMID: 27725702 PMCID: PMC5057128 DOI: 10.1038/srep35084] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 09/26/2016] [Indexed: 11/09/2022] Open
Abstract
The dynamin family of proteins play important regulatory roles in membrane remodelling and endocytosis, especially within brain and neuronal tissues. In the context of reproduction, dynamin 1 (DNM1) and dynamin 2 (DNM2) have recently been shown to act as key mediators of sperm acrosome formation and function. However, little is known about the roles that these proteins play in the developing testicular germ cells. In this study, we employed a DNM2 germ cell-specific knockout model to investigate the role of DNM2 in spermatogenesis. We demonstrate that ablation of DNM2 in early spermatogenesis results in germ cell arrest during prophase I of meiosis, subsequent loss of all post-meiotic germ cells and concomitant sterility. These effects become exacerbated with age, and ultimately result in the demise of the spermatogonial stem cells and a Sertoli cell only phenotype. We also demonstrate that DNM2 activity may be temporally regulated by phosphorylation of DNM2 via the kinase CDK1 in spermatogonia, and dephosphorylation by phosphatase PPP3CA during meiotic and post-meiotic spermatogenesis.
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Affiliation(s)
- Kate A Redgrove
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia.,PRC in Chemical Biology, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Ilana R Bernstein
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia.,PRC in Chemical Biology, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Victoria J Pye
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia.,PRC in Chemical Biology, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Bettina P Mihalas
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Jessie M Sutherland
- School of Biomedical Sciences &Pharmacy, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Brett Nixon
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia.,PRC in Chemical Biology, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Adam McCluskey
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia.,PRC in Chemical Biology, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Phillip J Robinson
- Cell Signalling Unit, Children's Medical Research Institute, University of Sydney, Sydney, NSW 2145, Australia
| | - Janet E Holt
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia.,PRC in Chemical Biology, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Eileen A McLaughlin
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia.,PRC in Chemical Biology, University of Newcastle, Callaghan, NSW 2308, Australia.,School of Biological Sciences, University of Auckland, Auckland 1010, New Zealand
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38
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Pereira EA, daSilva LLP. HIV-1 Nef: Taking Control of Protein Trafficking. Traffic 2016; 17:976-96. [PMID: 27161574 DOI: 10.1111/tra.12412] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 05/05/2016] [Accepted: 05/05/2016] [Indexed: 12/25/2022]
Abstract
The Nef protein of the human immunodeficiency virus is a crucial determinant of viral pathogenesis and disease progression. Nef is abundantly expressed early in infection and is thought to optimize the cellular environment for viral replication. Nef controls expression levels of various cell surface molecules that play important roles in immunity and virus life cycle, by directly interfering with the itinerary of these proteins within the endocytic and late secretory pathways. To exert these functions, Nef physically interacts with host proteins that regulate protein trafficking. In recent years, considerable progress was made in identifying host-cell-interacting partners for Nef, and the molecular machinery used by Nef to interfere with protein trafficking has started to be unraveled. Here, we briefly review the knowledge gained and discuss new findings regarding the mechanisms by which Nef modifies the intracellular trafficking pathways to prevent antigen presentation, facilitate viral particle release and enhance the infectivity of HIV-1 virions.
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Affiliation(s)
- Estela A Pereira
- Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Luis L P daSilva
- Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
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39
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Stevenson M. CROI 2016: Basic Science Review. TOPICS IN ANTIVIRAL MEDICINE 2016; 24:4-9. [PMID: 27398858 PMCID: PMC6148922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 04/13/2016] [Indexed: 06/06/2023]
Abstract
The 2016 Conference on Retroviruses and Opportunistic Infections continued to maintain balance in the representation of different areas of research related to HIV/AIDS. The basic science category encompasses research on viral reservoirs and HIV cure, on cellular factors regulating the interplay between virus and host, and on factors that influence viral pathogenicity. Basic research on factors that influence the interaction between the virus and the host cell continues to unearth surprises with the identification of a new host antiviral factor. Further, research into the mechanisms of viral persistence reveals that there is much to learn about how HIV-1 is able to persist in the face of antiviral suppression.
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40
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Remodeling of the Host Cell Plasma Membrane by HIV-1 Nef and Vpu: A Strategy to Ensure Viral Fitness and Persistence. Viruses 2016; 8:67. [PMID: 26950141 PMCID: PMC4810257 DOI: 10.3390/v8030067] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Revised: 02/09/2016] [Accepted: 02/16/2016] [Indexed: 02/07/2023] Open
Abstract
The plasma membrane protects the cell from its surroundings and regulates cellular communication, homing, and metabolism. Not surprisingly, the composition of this membrane is highly controlled through the vesicular trafficking of proteins to and from the cell surface. As intracellular pathogens, most viruses exploit the host plasma membrane to promote viral replication while avoiding immune detection. This is particularly true for the enveloped human immunodeficiency virus (HIV), which assembles and obtains its lipid shell directly at the plasma membrane. HIV-1 encodes two proteins, negative factor (Nef) and viral protein U (Vpu), which function primarily by altering the quantity and localization of cell surface molecules to increase virus fitness despite host antiviral immune responses. These proteins are expressed at different stages in the HIV-1 life cycle and employ a variety of mechanisms to target both unique and redundant surface proteins, including the viral receptor CD4, host restriction factors, immunoreceptors, homing molecules, tetraspanins and membrane transporters. In this review, we discuss recent progress in the study of the Nef and Vpu targeting of host membrane proteins with an emphasis on how remodeling of the cell membrane allows HIV-1 to avoid host antiviral immune responses leading to the establishment of systemic and persistent infection.
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41
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Serena M, Giorgetti A, Busato M, Gasparini F, Diani E, Romanelli MG, Zipeto D. Molecular characterization of HIV-1 Nef and ACOT8 interaction: insights from in silico structural predictions and in vitro functional assays. Sci Rep 2016; 6:22319. [PMID: 26927806 PMCID: PMC4772117 DOI: 10.1038/srep22319] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 02/11/2016] [Indexed: 11/29/2022] Open
Abstract
HIV-1 Nef interacts with several cellular proteins, among which the human peroxisomal thioesterase 8 (ACOT8). This interaction may be involved in the endocytosis regulation of membrane proteins and might modulate lipid composition in membrane rafts. Nef regions involved in the interaction have been experimentally characterized, whereas structural details of the ACOT8 protein are unknown. The lack of structural information hampers the comprehension of the functional consequences of the complex formation during HIV-1 infection. We modelled, through in silico predictions, the ACOT8 structure and we observed a high charge complementarity between Nef and ACOT8 surfaces, which allowed the identification of the ACOT8 putative contact points involved in the interaction. The predictions were validated by in vitro assays through the development of ACOT8 deletion mutants. Coimmunoprecipitation and immunofluorescence analyses showed that ACOT8 Arg45-Phe55 and Arg86-Pro93 regions are involved in Nef association. In addition, K91S mutation abrogated the interaction with Nef, indicating that Lys91 plays a key role in the interaction. Finally, when associated with ACOT8, Nef may be preserved from degradation. These findings improve the comprehension of the association between HIV-1 Nef and ACOT8, helping elucidating the biological effect of their interaction.
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Affiliation(s)
- Michela Serena
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Strada le Grazie 8, 37134 Verona, Italy
| | - Alejandro Giorgetti
- Department of Biotechnology, University of Verona, Strada le Grazie 15, 37134 Verona, Italy
| | - Mirko Busato
- Department of Biotechnology, University of Verona, Strada le Grazie 15, 37134 Verona, Italy
| | - Francesca Gasparini
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Strada le Grazie 8, 37134 Verona, Italy.,Department of Biotechnology, University of Verona, Strada le Grazie 15, 37134 Verona, Italy
| | - Erica Diani
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Strada le Grazie 8, 37134 Verona, Italy
| | - Maria Grazia Romanelli
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Strada le Grazie 8, 37134 Verona, Italy
| | - Donato Zipeto
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Strada le Grazie 8, 37134 Verona, Italy
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42
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Spotlight on HIV-1 Nef: SERINC3 and SERINC5 Identified as Restriction Factors Antagonized by the Pathogenesis Factor. Viruses 2015; 7:6730-8. [PMID: 26703715 PMCID: PMC4690893 DOI: 10.3390/v7122970] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 12/15/2015] [Accepted: 12/16/2015] [Indexed: 12/20/2022] Open
Abstract
The Nef protein is an accessory gene product encoded by human immunodeficiency virus types 1 and 2 (HIV-1/-2) and simian immunodeficiency virus (SIV) that boosts virus replication in the infected host and accelerates disease progression. Unlike the HIV-1 accessory proteins Vif, Vpr and Vpu, Nef was, until recently, not known to antagonize the antiviral activity of a host cell restriction factor. Two recent reports now describe the host cell proteins serine incorporator 3 and 5 (SERINC3 and SERINC5) as potent inhibitors of HIV-1 particle infectivity and demonstrate that Nef counteracts these effects. These findings establish SERINC3/5 as restrictions to HIV replication in human cells and define a novel activity for the HIV pathogenesis factor Nef.
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43
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44
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AP-2 Is the Crucial Clathrin Adaptor Protein for CD4 Downmodulation by HIV-1 Nef in Infected Primary CD4+ T Cells. J Virol 2015; 89:12518-24. [PMID: 26423947 DOI: 10.1128/jvi.01838-15] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 09/22/2015] [Indexed: 01/28/2023] Open
Abstract
HIV-1 Nef-mediated CD4 downmodulation involves various host factors. We investigated the importance of AP-1, AP-2, AP-3, V1H-ATPase, β-COP, and ACOT8 for CD4 downmodulation in HIV-1-infected short hairpin RNA (shRNA)-expressing CD4(+) T cells and characterized direct interaction with Nef by Förster resonance energy transfer (FRET). Binding of lentiviral Nefs to CD4 and AP-2 was conserved, and only AP-2 knockdown impaired Nef-mediated CD4 downmodulation from primary T cells. Altogether, among the factors tested, AP-2 is the most important player for Nef-mediated CD4 downmodulation.
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45
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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.
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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
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46
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HIV-1 Nef promotes infection by excluding SERINC5 from virion incorporation. Nature 2015; 526:212-7. [PMID: 26416734 DOI: 10.1038/nature15399] [Citation(s) in RCA: 319] [Impact Index Per Article: 35.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 08/18/2015] [Indexed: 12/18/2022]
Abstract
HIV-1 Nef, a protein important for the development of AIDS, has well-characterized effects on host membrane trafficking and receptor downregulation. By an unidentified mechanism, Nef increases the intrinsic infectivity of HIV-1 virions in a host-cell-dependent manner. Here we identify the host transmembrane protein SERINC5, and to a lesser extent SERINC3, as a potent inhibitor of HIV-1 particle infectivity that is counteracted by Nef. SERINC5 localizes to the plasma membrane, where it is efficiently incorporated into budding HIV-1 virions and impairs subsequent virion penetration of susceptible target cells. Nef redirects SERINC5 to a Rab7-positive endosomal compartment and thereby excludes it from HIV-1 particles. The ability to counteract SERINC5 was conserved in Nef encoded by diverse primate immunodeficiency viruses, as well as in the structurally unrelated glycosylated Gag from murine leukaemia virus. These examples of functional conservation and convergent evolution emphasize the fundamental importance of SERINC5 as a potent anti-retroviral factor.
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47
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Association with PAK2 Enables Functional Interactions of Lentiviral Nef Proteins with the Exocyst Complex. mBio 2015; 6:e01309-15. [PMID: 26350970 PMCID: PMC4600113 DOI: 10.1128/mbio.01309-15] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
UNLABELLED Human immunodeficiency virus type 1 (HIV-1) Nef enhances virus replication and contributes to immune evasion in vivo, but the underlying molecular mechanisms remain incompletely defined. Nef interferes with host cell actin dynamics to restrict T lymphocyte responses to chemokine stimulation and T cell receptor engagement. This relies on the assembly of a labile multiprotein complex including the host kinase PAK2 that Nef usurps to phosphorylate and inactivate the actin-severing factor cofilin. Components of the exocyst complex (EXOC), an octameric protein complex involved in vesicular transport and actin remodeling, were recently reported to interact with Nef via the same molecular surface that mediates PAK2 association. Exploring the functional relevance of EXOC in Nef-PAK2 complex assembly/function, we found Nef-EXOC interactions to be specifically mediated by the PAK2 interface of Nef, to occur in infected human T lymphocytes, and to be conserved among lentiviral Nef proteins. In turn, EXOC was dispensable for direct downstream effector functions of Nef-associated PAK2. Surprisingly, PAK2 was essential for Nef-EXOC association, which required a functional Rac1/Cdc42 binding site but not the catalytic activity of PAK2. EXOC was dispensable for Nef functions in vesicular transport but critical for inhibition of actin remodeling and proximal signaling upon T cell receptor engagement. Thus, Nef exploits PAK2 in a stepwise mechanism in which its kinase activity cooperates with an adaptor function for EXOC to inhibit host cell actin dynamics. IMPORTANCE Human immunodeficiency virus type 1 (HIV-1) Nef contributes to AIDS pathogenesis, but the underlying molecular mechanisms remain incompletely understood. An important aspect of Nef function is to facilitate virus replication by disrupting T lymphocyte actin dynamics in response to stimulation via its association with the host cell kinase PAK2. We report here that the molecular surface of Nef for PAK2 association also mediates interaction of Nef with EXOC and establish that PAK2 provides an essential adaptor function for the subsequent formation of Nef-EXOC complexes. PAK2 and EXOC specifically cooperate in the inhibition of actin dynamics and proximal signaling induced by T cell receptor engagement by Nef. These results establish EXOC as a functionally relevant Nef interaction partner, emphasize the suitability of the PAK2 interaction surface for future therapeutic interference with Nef function, and show that such strategies need to target activity-independent PAK2 functions.
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Nakano Y, Matsuda K, Yoshikawa R, Yamada E, Misawa N, Hirsch VM, Koyanagi Y, Sato K. Down-modulation of primate lentiviral receptors by Nef proteins of simian immunodeficiency virus (SIV) of chimpanzees (SIVcpz) and related SIVs: implication for the evolutionary event at the emergence of SIVcpz. J Gen Virol 2015; 96:2867-2877. [PMID: 26041873 DOI: 10.1099/vir.0.000207] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
It has been estimated that human immunodeficiency virus type 1 originated from the zoonotic transmission of simian immunodeficiency virus (SIV) of chimpanzees, SIVcpz, and that SIVcpz emerged by the recombination of two lineages of SIVs in Old World monkeys (SIVgsn/mon/mus in guenons and SIVrcm in red-capped mangabeys) and SIVcpz Nef is most closely related to SIVrcm Nef. These observations suggest that SIVrcm Nef had an advantage over SIVgsn/mon/mus during the evolution of SIVcpz in chimpanzees, although this advantage remains uncertain. Nef is a multifunctional protein which downregulates CD4 and coreceptor proteins from the surface of infected cells, presumably to limit superinfection. To assess the possibility that SIVrcm Nef was selected by its superior ability to downregulate viral entry receptors in chimpanzees, we compared its ability to down-modulate viral receptor proteins from humans, chimpanzees and red-capped mangabeys with Nef proteins from eight other different strains of SIVs. Surprisingly, the ability of SIVrcm Nef to downregulate CCR5, CCR2B and CXCR6 was comparable to or lower than SIVgsn/mon/mus Nef, indicating that ability to down-modulate chemokine receptors was not the selective pressure. However, SIVrcm Nef significantly downregulates chimpanzee CD4 over SIVgsn/mon/mus Nefs. Our findings suggest the possibility that the selection of SIVrcm Nef by ancestral SIVcpz is due to its superior capacity to down-modulate chimpanzees CD4 rather than coreceptor proteins.
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Affiliation(s)
- Yusuke Nakano
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan
- Department of Medical Virology, Faculty of Life Sciences, Kumamoto University, Kumamoto 8608556, Japan
| | - Kenta Matsuda
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Rokusuke Yoshikawa
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan
| | - Eri Yamada
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan
| | - Naoko Misawa
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan
| | - Vanessa M Hirsch
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yoshio Koyanagi
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan
| | - Kei Sato
- CREST, Japan Science and Technology Agency, Saitama 3220012, Japan
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan
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Yamada E, Yoshikawa R, Nakano Y, Misawa N, Koyanagi Y, Sato K. Impacts of humanized mouse models on the investigation of HIV-1 infection: illuminating the roles of viral accessory proteins in vivo. Viruses 2015; 7:1373-90. [PMID: 25807049 PMCID: PMC4379576 DOI: 10.3390/v7031373] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 03/10/2015] [Accepted: 03/10/2015] [Indexed: 12/26/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) encodes four accessory genes: vif, vpu, vpr, and nef. Recent investigations using in vitro cell culture systems have shed light on the roles of these HIV-1 accessory proteins, Vif, Vpr, Vpu, and Nef, in counteracting, modulating, and evading various cellular factors that are responsible for anti-HIV-1 intrinsic immunity. However, since humans are the exclusive target for HIV-1 infection, conventional animal models are incapable of mimicking the dynamics of HIV-1 infection in vivo. Moreover, the effects of HIV-1 accessory proteins on viral infection in vivo remain unclear. To elucidate the roles of HIV-1 accessory proteins in the dynamics of viral infection in vivo, humanized mouse models, in which the mice are xenotransplanted with human hematopoietic stem cells, has been utilized. This review describes the current knowledge of the roles of HIV-1 accessory proteins in viral infection, replication, and pathogenicity in vivo, which are revealed by the studies using humanized mouse models.
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Affiliation(s)
- Eri Yamada
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan.
| | - Rokusuke Yoshikawa
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan.
| | - Yusuke Nakano
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan.
| | - Naoko Misawa
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan.
| | - Yoshio Koyanagi
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan.
| | - Kei Sato
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan.
- CREST, Japan Science and Technology Agency, Saitama 3220012, Japan.
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Vpu is the main determinant for tetraspanin downregulation in HIV-1-infected cells. J Virol 2015; 89:3247-55. [PMID: 25568205 DOI: 10.1128/jvi.03719-14] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
UNLABELLED Tetraspanins constitute a family of cellular proteins that organize various membrane-based processes. Several members of this family, including CD81, are actively recruited by HIV-1 Gag to viral assembly and release sites. Despite their enrichment at viral exit sites, the overall levels of tetraspanins are decreased in HIV-1-infected cells. Here, we identify Vpu as the main viral determinant for tetraspanin downregulation. We also show that reduction of CD81 levels by Vpu is not a by-product of CD4 or BST-2/tetherin elimination from the surfaces of infected cells and likely occurs through an interaction between Vpu and CD81. Finally, we document that Vpu-mediated downregulation of CD81 from the surfaces of infected T cells can contribute to preserving the infectiousness of viral particles, thus revealing a novel Vpu function that promotes virus propagation by modulating the host cell environment. IMPORTANCE The HIV-1 accessory protein Vpu has previously been shown to downregulate various host cell factors, thus helping the virus to overcome restriction barriers, evade immune attack, and maintain the infectivity of viral particles. Our study identifies tetraspanins as an additional group of host factors whose expression at the surfaces of infected cells is lowered by Vpu. While the downregulation of these integral membrane proteins, including CD81 and CD82, likely affects more than one function of HIV-1-infected cells, we document that Vpu-mediated lowering of CD81 levels in viral particles can be critical to maintaining their infectiousness.
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