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Padron A, Dwivedi R, Chakraborty R, Prakash P, Kim K, Shi J, Ahn J, Pandhare J, Luban J, Aiken C, Balasubramaniam M, Dash C. Cyclophilin A Facilitates HIV-1 DNA Integration. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.15.599180. [PMID: 38948800 PMCID: PMC11212919 DOI: 10.1101/2024.06.15.599180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/02/2024]
Abstract
Cyclophilin A (CypA) promotes HIV-1 infection by facilitating reverse transcription, nuclear entry and by countering the antiviral activity of TRIM5α. These multifunctional roles of CypA are driven by its binding to the viral capsid. Interestingly, recent studies suggest that the HIV-1 capsid lattice enters the nucleus of an infected cell and uncoats just before integration. Therefore, we tested whether CypA-capsid interaction regulates post-nuclear entry steps of infection, particularly integration. First, we challenged CypA-expressing (CypA +/+ ) and CypA-depleted (CypA -/- ) cells with HIV-1 particles and quantified the resulting levels of provirus. Surprisingly, CypA-depletion significantly reduced integration, an effect that was independent of CypA's effect on reverse transcription, nuclear entry, and the presence or absence of TRIM5α. Additionally, cyclosporin A, an inhibitor that disrupts CypA-capsid binding, inhibited HIV-1 integration in CypA +/+ cells but not in CypA -/- cells. Accordingly, HIV-1 capsid mutants (G89V and P90A) deficient in CypA binding were also blocked at integration in CypA +/+ cells but not in CypA -/- cells. Then, to understand the mechanism, we assessed the integration activity of HIV-1 preintegration complexes (PICs) extracted from infected cells. The PICs from CypA -/- cells had lower activity in vitro compared to those from CypA +/+ cells. PICs from cells depleted for CypA and TRIM5α also had lower activity, suggesting that CypA's effect on PIC activity is independent of TRIM5α. Finally, addition of CypA protein significantly stimulated the integration activity of PICs extracted from both CypA +/+ and CypA -/- cells. Collectively, these results suggest that CypA promotes HIV-1 integration, a previously unknown role of this host factor. Importance HIV-1 capsid interaction with host cellular factors is essential for establishing a productive infection. However, the molecular details of such virus-host interactions are not fully understood. Cyclophilin A (CypA) is the first host protein identified to specifically bind to the HIV-1 capsid. Now it is established that CypA promotes reverse transcription and nuclear entry steps of HIV-1 infection. In this report, we show that CypA promotes HIV-1 integration by binding to the viral capsid. Specifically, our results demonstrate that CypA promotes HIV-1 integration by stimulating the activity of the viral preintegration complex and identifies a novel role of CypA during HIV-1 infection. This new knowledge is important because recent reports suggest that an operationally intact HIV-1 capsid enters the nucleus of an infected cell.
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2
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Ritter C, Lee JY, Pham MT, Pabba MK, Cardoso MC, Bartenschlager R, Rohr K. Multi-detector fusion and Bayesian smoothing for tracking viral and chromatin structures. Med Image Anal 2024; 97:103227. [PMID: 38897031 DOI: 10.1016/j.media.2024.103227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 08/15/2023] [Accepted: 05/27/2024] [Indexed: 06/21/2024]
Abstract
Automatic tracking of viral and intracellular structures displayed as spots with varying sizes in fluorescence microscopy images is an important task to quantify cellular processes. We propose a novel probabilistic tracking approach for multiple particle tracking based on multi-detector and multi-scale data fusion as well as Bayesian smoothing. The approach integrates results from multiple detectors using a novel intensity-based covariance intersection method which takes into account information about the image intensities, positions, and uncertainties. The method ensures a consistent estimate of multiple fused particle detections and does not require an optimization step. Our probabilistic tracking approach performs data fusion of detections from classical and deep learning methods as well as exploits single-scale and multi-scale detections. In addition, we use Bayesian smoothing to fuse information of predictions from both past and future time points. We evaluated our approach using image data of the Particle Tracking Challenge and achieved state-of-the-art results or outperformed previous methods. Our method was also assessed on challenging live cell fluorescence microscopy image data of viral and cellular proteins expressed in hepatitis C virus-infected cells and chromatin structures in non-infected cells, acquired at different spatial-temporal resolutions. We found that the proposed approach outperforms existing methods.
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Affiliation(s)
- C Ritter
- Biomedical Computer Vision Group, BioQuant, IPMB, Heidelberg University, Im Neuenheimer Feld 267, Heidelberg, Germany.
| | - J-Y Lee
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 344, Heidelberg, Germany; German Center for Infection Research (DZIF), Heidelberg Partner Site, Germany
| | - M-T Pham
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 344, Heidelberg, Germany; German Center for Infection Research (DZIF), Heidelberg Partner Site, Germany
| | - M K Pabba
- Department of Biology, Cell Biology and Epigenetics, Technical University of Darmstadt, Schnittspahnstraße 10, Darmstadt, Germany
| | - M C Cardoso
- Department of Biology, Cell Biology and Epigenetics, Technical University of Darmstadt, Schnittspahnstraße 10, Darmstadt, Germany
| | - R Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 344, Heidelberg, Germany; German Center for Infection Research (DZIF), Heidelberg Partner Site, Germany
| | - K Rohr
- Biomedical Computer Vision Group, BioQuant, IPMB, Heidelberg University, Im Neuenheimer Feld 267, Heidelberg, Germany.
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3
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Minoshima M, Reja SI, Hashimoto R, Iijima K, Kikuchi K. Hybrid Small-Molecule/Protein Fluorescent Probes. Chem Rev 2024; 124:6198-6270. [PMID: 38717865 DOI: 10.1021/acs.chemrev.3c00549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2024]
Abstract
Hybrid small-molecule/protein fluorescent probes are powerful tools for visualizing protein localization and function in living cells. These hybrid probes are constructed by diverse site-specific chemical protein labeling approaches through chemical reactions to exogenous peptide/small protein tags, enzymatic post-translational modifications, bioorthogonal reactions for genetically incorporated unnatural amino acids, and ligand-directed chemical reactions. The hybrid small-molecule/protein fluorescent probes are employed for imaging protein trafficking, conformational changes, and bioanalytes surrounding proteins. In addition, fluorescent hybrid probes facilitate visualization of protein dynamics at the single-molecule level and the defined structure with super-resolution imaging. In this review, we discuss development and the bioimaging applications of fluorescent probes based on small-molecule/protein hybrids.
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Affiliation(s)
- Masafumi Minoshima
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita, Osaka 5650871, Japan
| | - Shahi Imam Reja
- Immunology Frontier Research Center, Osaka University, 2-1, Yamadaoka, Suita, Osaka 5650871, Japan
| | - Ryu Hashimoto
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita, Osaka 5650871, Japan
| | - Kohei Iijima
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita, Osaka 5650871, Japan
| | - Kazuya Kikuchi
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita, Osaka 5650871, Japan
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4
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Stephens C, Naghavi MH. The host cytoskeleton: a key regulator of early HIV-1 infection. FEBS J 2024; 291:1835-1848. [PMID: 36527282 PMCID: PMC10272291 DOI: 10.1111/febs.16706] [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: 10/21/2022] [Revised: 11/29/2022] [Accepted: 12/16/2022] [Indexed: 12/23/2022]
Abstract
Due to its central role in cell biology, the cytoskeleton is a key regulator of viral infection, influencing nearly every step of the viral life cycle. In this review, we will discuss the role of two key components of the cytoskeleton, namely the actin and microtubule networks in early HIV-1 infection. We will discuss key contributions to processes ranging from the attachment and entry of viral particles at the cell surface to their arrival and import into the nucleus and identify areas where further research into this complex relationship may yield new insights into HIV-1 pathogenesis.
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Affiliation(s)
- Christopher Stephens
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611, USA
| | - Mojgan H. Naghavi
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611, USA
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5
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Burdick RC, Duchon A, Hu WS, Pathak VK. Imaging HIV-1 Nuclear Import, Uncoating, and Proviral Transcription. Methods Mol Biol 2024; 2807:15-30. [PMID: 38743218 DOI: 10.1007/978-1-0716-3862-0_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Live-cell imaging has become a powerful tool for dissecting the behavior of viral complexes during HIV-1 infection with high temporal and spatial resolution. Very few HIV-1 particles in a viral population are infectious and successfully complete replication (~1/50). Single-particle live-cell imaging enables the study of these rare infectious viral particles, which cannot be accomplished in biochemical assays that measure the average property of the entire viral population, most of which are not infectious. The timing and location of many events in the early stage of the HIV-1 life cycle, including nuclear import, uncoating, and integration, have only recently been elucidated. Live-cell imaging also provides a valuable approach to study interactions of viral and host factors in distinct cellular compartments and at specific stages of viral replication. Successful live-cell imaging experiments require careful consideration of the fluorescent labeling method used and avoid or minimize its potential impact on normal viral replication and produce misleading results. Ideally, it is beneficial to utilize multiple virus labeling strategies and compare the results to ensure that the virion labeling did not adversely influence the viral replication step that is under investigation. Another potential benefit of using different labeling strategies is that they can provide information about the state of the viral complexes. Here, we describe our methods that utilize multiple fluorescent protein labeling approaches to visualize and quantify important events in the HIV-1 life cycle, including docking HIV-1 particles with the nuclear envelope (NE) and their nuclear import, uncoating, and proviral transcription.
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Affiliation(s)
- Ryan C Burdick
- Viral Mutation Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD, USA
| | - Alice Duchon
- Viral Recombination Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD, USA
| | - Wei-Shau Hu
- Viral Recombination Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD, USA
| | - Vinay K Pathak
- Viral Mutation Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD, USA.
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6
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Badieyan S, Lichon D, Andreas MP, Gillies JP, Peng W, Shi J, DeSantis ME, Aiken CR, Böcking T, Giessen TW, Campbell EM, Cianfrocco MA. HIV-1 binds dynein directly to hijack microtubule transport machinery. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.29.555335. [PMID: 37693451 PMCID: PMC10491134 DOI: 10.1101/2023.08.29.555335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Viruses exploit host cytoskeletal elements and motor proteins for trafficking through the dense cytoplasm. Yet the molecular mechanism that describes how viruses connect to the motor machinery is unknown. Here, we demonstrate the first example of viral microtubule trafficking from purified components: HIV-1 hijacking microtubule transport machinery. We discover that HIV-1 directly binds to the retrograde microtubule-associated motor, dynein, and not via a cargo adaptor, as previously suggested. Moreover, we show that HIV-1 motility is supported by multiple, diverse dynein cargo adaptors as HIV-1 binds to dynein light and intermediate chains on dynein's tail. Further, we demonstrate that multiple dynein motors tethered to rigid cargoes, like HIV-1 capsids, display reduced motility, distinct from the behavior of multiple motors on membranous cargoes. Our results introduce a new model of viral trafficking wherein a pathogen opportunistically 'hijacks' the microtubule transport machinery for motility, enabling multiple transport pathways through the host cytoplasm.
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Affiliation(s)
| | - Drew Lichon
- Department of Microbiology and Immunology, Stritch School of Medicine, Loyola University Chicago, IL, USA
| | - Michael P Andreas
- Department of Biological Chemistry, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - John P Gillies
- Department of Molecular, Cellular, and Developmental Biology, College of Literature, Sciences, and the Arts, University of Michigan, Ann Arbor, MI USA
| | - Wang Peng
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW Sydney, Sydney, New South Wales, Australia
| | - Jiong Shi
- Department of Pathology, Microbiology, and Immunology, Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Morgan E DeSantis
- Department of Molecular, Cellular, and Developmental Biology, College of Literature, Sciences, and the Arts, University of Michigan, Ann Arbor, MI USA
| | - Christopher R Aiken
- Department of Pathology, Microbiology, and Immunology, Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Till Böcking
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW Sydney, Sydney, New South Wales, Australia
| | - Tobias W Giessen
- Department of Biological Chemistry, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Edward M Campbell
- Department of Microbiology and Immunology, Stritch School of Medicine, Loyola University Chicago, IL, USA
| | - Michael A Cianfrocco
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Biological Chemistry, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
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7
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Padron A, Prakash P, Pandhare J, Luban J, Aiken C, Balasubramaniam M, Dash C. Emerging role of cyclophilin A in HIV-1 infection: from producer cell to the target cell nucleus. J Virol 2023; 97:e0073223. [PMID: 37843371 PMCID: PMC10688351 DOI: 10.1128/jvi.00732-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2023] Open
Abstract
The HIV-1 genome encodes a small number of proteins with structural, enzymatic, regulatory, and accessory functions. These viral proteins interact with a number of host factors to promote the early and late stages of HIV-1 infection. During the early stages of infection, interactions between the viral proteins and host factors enable HIV-1 to enter the target cell, traverse the cytosol, dock at the nuclear pore, gain access to the nucleus, and integrate into the host genome. Similarly, the viral proteins recruit another set of host factors during the late stages of infection to orchestrate HIV-1 transcription, translation, assembly, and release of progeny virions. Among the host factors implicated in HIV-1 infection, Cyclophilin A (CypA) was identified as the first host factor to be packaged within HIV-1 particles. It is now well established that CypA promotes HIV-1 infection by directly binding to the viral capsid. Mechanistic models to pinpoint CypA's role have spanned from an effect in the producer cell to the early steps of infection in the target cell. In this review, we will describe our understanding of the role(s) of CypA in HIV-1 infection, highlight the current knowledge gaps, and discuss the potential role of this host factor in the post-nuclear entry steps of HIV-1 infection.
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Affiliation(s)
- Adrian Padron
- The Center for AIDS Health Disparities Research, Meharry Medical College, Nashville, Tennessee, USA
- Department of Microbiology, Immunology, and Physiology, Meharry Medical College, Nashville, Tennessee, USA
- School of Graduate Studies, Meharry Medical College, Nashville, Tennessee, USA
| | - Prem Prakash
- The Center for AIDS Health Disparities Research, Meharry Medical College, Nashville, Tennessee, USA
- Department of Biochemistry, Cancer Biology, Pharmacology and Neuroscience, Meharry Medical College, Nashville, Tennessee, USA
| | - Jui Pandhare
- The Center for AIDS Health Disparities Research, Meharry Medical College, Nashville, Tennessee, USA
- Department of Microbiology, Immunology, and Physiology, Meharry Medical College, Nashville, Tennessee, USA
- School of Graduate Studies, Meharry Medical College, Nashville, Tennessee, USA
| | - Jeremy Luban
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Chris Aiken
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Muthukumar Balasubramaniam
- The Center for AIDS Health Disparities Research, Meharry Medical College, Nashville, Tennessee, USA
- Department of Biochemistry, Cancer Biology, Pharmacology and Neuroscience, Meharry Medical College, Nashville, Tennessee, USA
| | - Chandravanu Dash
- The Center for AIDS Health Disparities Research, Meharry Medical College, Nashville, Tennessee, USA
- Department of Microbiology, Immunology, and Physiology, Meharry Medical College, Nashville, Tennessee, USA
- Department of Biochemistry, Cancer Biology, Pharmacology and Neuroscience, Meharry Medical College, Nashville, Tennessee, USA
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8
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Cherayil BJ. Survival probabilities and first-passage distributions of self-propelled particles in spherical cavities. Phys Rev E 2023; 108:054607. [PMID: 38115486 DOI: 10.1103/physreve.108.054607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 11/05/2023] [Indexed: 12/21/2023]
Abstract
A model of self-propelled motion in a closed compartment containing simple or complex fluids is formulated in this paper in terms of the dynamics of a point particle moving in a spherical cavity under the action of random thermal forces and exponentially correlated noise. The particle's time evolution is governed by a generalized Langevin equation (GLE) in which the memory function, connected to the thermal forces by a fluctuation-dissipation relation, is described by Jeffrey's model of viscoelasticity (which reduces to a model of ordinary viscous dynamics in a suitable limit). The GLE is transformed exactly to a Fokker-Planck equation that in spherical polar coordinates is in turn found to admit of an exact solution for the particle's probability density function under absorbing boundary conditions at the surface of the sphere. The solution is used to derive an expression (that is also exact) for the survival probability of the particle in the sphere, starting from its center, which is then used to calculate the distribution of the particle's first-passage times to the boundary. The behavior of these quantities is investigated as a function of the Péclet number and the persistence time of the athermal forces, providing insight into the effects of nonequilibrium fluctuations on confined particle motion in three dimensions.
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Affiliation(s)
- Binny J Cherayil
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012, Karnataka, India
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9
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Cabrera-Rodríguez R, Pérez-Yanes S, Lorenzo-Sánchez I, Trujillo-González R, Estévez-Herrera J, García-Luis J, Valenzuela-Fernández A. HIV Infection: Shaping the Complex, Dynamic, and Interconnected Network of the Cytoskeleton. Int J Mol Sci 2023; 24:13104. [PMID: 37685911 PMCID: PMC10487602 DOI: 10.3390/ijms241713104] [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: 08/08/2023] [Revised: 08/21/2023] [Accepted: 08/22/2023] [Indexed: 09/10/2023] Open
Abstract
HIV-1 has evolved a plethora of strategies to overcome the cytoskeletal barrier (i.e., actin and intermediate filaments (AFs and IFs) and microtubules (MTs)) to achieve the viral cycle. HIV-1 modifies cytoskeletal organization and dynamics by acting on associated adaptors and molecular motors to productively fuse, enter, and infect cells and then traffic to the cell surface, where virions assemble and are released to spread infection. The HIV-1 envelope (Env) initiates the cycle by binding to and signaling through its main cell surface receptors (CD4/CCR5/CXCR4) to shape the cytoskeleton for fusion pore formation, which permits viral core entry. Then, the HIV-1 capsid is transported to the nucleus associated with cytoskeleton tracks under the control of specific adaptors/molecular motors, as well as HIV-1 accessory proteins. Furthermore, HIV-1 drives the late stages of the viral cycle by regulating cytoskeleton dynamics to assure viral Pr55Gag expression and transport to the cell surface, where it assembles and buds to mature infectious virions. In this review, we therefore analyze how HIV-1 generates a cell-permissive state to infection by regulating the cytoskeleton and associated factors. Likewise, we discuss the relevance of this knowledge to understand HIV-1 infection and pathogenesis in patients and to develop therapeutic strategies to battle HIV-1.
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Affiliation(s)
- Romina Cabrera-Rodríguez
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Ciencias de la Salud, Universidad de La Laguna (ULL), 38200 La Laguna, Spain; (R.C.-R.); (S.P.-Y.); (I.L.-S.); (R.T.-G.); (J.E.-H.); (J.G.-L.)
| | - Silvia Pérez-Yanes
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Ciencias de la Salud, Universidad de La Laguna (ULL), 38200 La Laguna, Spain; (R.C.-R.); (S.P.-Y.); (I.L.-S.); (R.T.-G.); (J.E.-H.); (J.G.-L.)
| | - Iria Lorenzo-Sánchez
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Ciencias de la Salud, Universidad de La Laguna (ULL), 38200 La Laguna, Spain; (R.C.-R.); (S.P.-Y.); (I.L.-S.); (R.T.-G.); (J.E.-H.); (J.G.-L.)
| | - Rodrigo Trujillo-González
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Ciencias de la Salud, Universidad de La Laguna (ULL), 38200 La Laguna, Spain; (R.C.-R.); (S.P.-Y.); (I.L.-S.); (R.T.-G.); (J.E.-H.); (J.G.-L.)
- Analysis Department, Faculty of Mathematics, Universidad de La Laguna (ULL), 38200 La Laguna, Spain
| | - Judith Estévez-Herrera
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Ciencias de la Salud, Universidad de La Laguna (ULL), 38200 La Laguna, Spain; (R.C.-R.); (S.P.-Y.); (I.L.-S.); (R.T.-G.); (J.E.-H.); (J.G.-L.)
| | - Jonay García-Luis
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Ciencias de la Salud, Universidad de La Laguna (ULL), 38200 La Laguna, Spain; (R.C.-R.); (S.P.-Y.); (I.L.-S.); (R.T.-G.); (J.E.-H.); (J.G.-L.)
| | - Agustín Valenzuela-Fernández
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Ciencias de la Salud, Universidad de La Laguna (ULL), 38200 La Laguna, Spain; (R.C.-R.); (S.P.-Y.); (I.L.-S.); (R.T.-G.); (J.E.-H.); (J.G.-L.)
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10
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Santos MF, Rappa G, Karbanová J, Diana P, Cirrincione G, Carbone D, Manna D, Aalam F, Wang D, Vanier C, Corbeil D, Lorico A. HIV-1-induced nuclear invaginations mediated by VAP-A, ORP3, and Rab7 complex explain infection of activated T cells. Nat Commun 2023; 14:4588. [PMID: 37563144 PMCID: PMC10415338 DOI: 10.1038/s41467-023-40227-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 07/19/2023] [Indexed: 08/12/2023] Open
Abstract
The mechanism of human immunodeficiency virus 1 (HIV-1) nuclear entry, required for productive infection, is not fully understood. Here, we report that in HeLa cells and activated CD4+ T cells infected with HIV-1 pseudotyped with VSV-G and native Env protein, respectively, Rab7+ late endosomes containing endocytosed HIV-1 promote the formation of nuclear envelope invaginations (NEIs) by a molecular mechanism involving the VOR complex, composed of the outer nuclear membrane protein VAP-A, hyperphosphorylated ORP3 and Rab7. Silencing VAP-A or ORP3 and drug-mediated impairment of Rab7 binding to ORP3-VAP-A inhibited the nuclear transfer of the HIV-1 components and productive infection. In HIV-1-resistant quiescent CD4+ T cells, ORP3 was not hyperphosphorylated and neither VOR complex nor NEIs were formed. This new cellular pathway and its molecular players are potential therapeutic targets, perhaps shared by other viruses that require nuclear entry to complete their life cycle.
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Affiliation(s)
- Mark F Santos
- Touro University Nevada College of Osteopathic Medicine, Henderson, NV, USA
| | - Germana Rappa
- Touro University Nevada College of Osteopathic Medicine, Henderson, NV, USA
| | - Jana Karbanová
- Biotechnology Center (BIOTEC) and Center for Molecular and Cellular Bioengineering, Technische Universität Dresden, Dresden, Germany
| | - Patrizia Diana
- Department of Biological, Chemical, and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Palermo, Italy
| | - Girolamo Cirrincione
- Department of Biological, Chemical, and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Palermo, Italy
| | - Daniela Carbone
- Department of Biological, Chemical, and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Palermo, Italy
| | - David Manna
- Touro College of Osteopathic Medicine, Middletown, New York, NY, USA
| | - Feryal Aalam
- Touro University Nevada College of Osteopathic Medicine, Henderson, NV, USA
| | - David Wang
- Touro University Nevada College of Osteopathic Medicine, Henderson, NV, USA
| | - Cheryl Vanier
- Touro University Nevada College of Osteopathic Medicine, Henderson, NV, USA
- Imgen Research, LLC, 5495 South Rainbow #201, Las Vegas, NV, USA
| | - Denis Corbeil
- Biotechnology Center (BIOTEC) and Center for Molecular and Cellular Bioengineering, Technische Universität Dresden, Dresden, Germany.
| | - Aurelio Lorico
- Touro University Nevada College of Osteopathic Medicine, Henderson, NV, USA.
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11
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Malikov V, Naghavi MH. FEZ1 Plays Dual Roles in Early HIV-1 Infection by Independently Regulating Capsid Transport and Host Interferon-Stimulated Gene Expression. J Virol 2023; 97:e0049923. [PMID: 37219433 PMCID: PMC10308898 DOI: 10.1128/jvi.00499-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 05/05/2023] [Indexed: 05/24/2023] Open
Abstract
Fasciculation and elongation factor zeta 1 (FEZ1), a multifunctional kinesin-1 adaptor, binds human immunodeficiency virus type 1 (HIV-1) capsids and is required for efficient translocation of virus particles to the nucleus to initiate infection. However, we recently found that FEZ1 also acts as a negative regulator of interferon (IFN) production and interferon-stimulated gene (ISG) expression in primary fibroblasts and human immortalized microglial cell line clone 3 (CHME3) microglia, a natural target cell type for HIV-1 infection. This raises the question of whether depleting FEZ1 negatively affects early HIV-1 infection through effects on virus trafficking or IFN induction or both. Here, we address this by comparing the effects of FEZ1 depletion or IFN-β treatment on early stages of HIV-1 infection in different cell systems with various IFN-β responsiveness. In either CHME3 microglia or HEK293A cells, depletion of FEZ1 reduced the accumulation of fused HIV-1 particles around the nucleus and suppressed infection. In contrast, various doses of IFN-β had little to no effect on HIV-1 fusion or the translocation of fused viral particles to the nucleus in either cell type. Moreover, the potency of IFN-β's effects on infection in each cell type reflected the level of induction of MxB, an ISG that blocks subsequent stages of HIV-1 nuclear import. Collectively, our findings demonstrate that loss of FEZ1 function impacts infection through its roles in two independent processes, as a direct regulator of HIV-1 particle transport and as a regulator of ISG expression. IMPORTANCE As a hub protein, fasciculation and elongation factor zeta 1 (FEZ1) interacts with a range of other proteins involved in various biological processes, acting as an adaptor for the microtubule (MT) motor kinesin-1 to mediate outward transport of intracellular cargoes, including viruses. Indeed, incoming HIV-1 capsids bind to FEZ1 to regulate the balance of inward/outward motor activity to ensure net forward movement toward the nucleus to initiate infection. However, we recently showed that FEZ1 depletion also induces interferon (IFN) production and interferon-stimulated gene (ISG) expression. As such, it remains unknown whether modulating FEZ1 activity affects HIV-1 infection through its ability to regulate ISG expression or whether FEZ1 functions directly, or both. Using distinct cell systems that separate the effects of IFN and FEZ1 depletion, here we demonstrate that the kinesin adaptor FEZ1 regulates HIV-1 translocation to the nucleus independently of its effects on IFN production and ISG expression.
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Affiliation(s)
- Viacheslav Malikov
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Mojgan H. Naghavi
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
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12
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da Silva ES, Naghavi MH. Microtubules and viral infection. Adv Virus Res 2023; 115:87-134. [PMID: 37173066 DOI: 10.1016/bs.aivir.2023.02.003] [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] [Indexed: 04/05/2023]
Abstract
Microtubules (MTs) form rapidly adaptable, complex intracellular networks of filaments that not only provide structural support, but also form the tracks along which motors traffic macromolecular cargos to specific sub-cellular sites. These dynamic arrays play a central role in regulating various cellular processes including cell shape and motility as well as cell division and polarization. Given their complex organization and functional importance, MT arrays are carefully controlled by many highly specialized proteins that regulate the nucleation of MT filaments at distinct sites, their dynamic growth and stability, and their engagement with other subcellular structures and cargoes destined for transport. This review focuses on recent advances in our understanding of how MTs and their regulatory proteins function, including their active targeting and exploitation, during infection by viruses that utilize a wide variety of replication strategies that occur within different cellular sub-compartments or regions of the cell.
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Affiliation(s)
- Eveline Santos da Silva
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States; HIV Clinical and Translational Research, Luxembourg Institute of Health, Department of Infection and Immunity, Esch-sur-Alzette, Luxembourg
| | - Mojgan H Naghavi
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States.
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13
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Río-Bergé C, Cong Y, Reggiori F. Getting on the right track: Interactions between viruses and the cytoskeletal motor proteins. Traffic 2023; 24:114-130. [PMID: 35146839 DOI: 10.1111/tra.12835] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 02/06/2022] [Accepted: 02/07/2022] [Indexed: 11/29/2022]
Abstract
The cytoskeleton is an essential component of the cell and it is involved in multiple physiological functions, including intracellular organization and transport. It is composed of three main families of proteinaceous filaments; microtubules, actin filaments and intermediate filaments and their accessory proteins. Motor proteins, which comprise the dynein, kinesin and myosin superfamilies, are a remarkable group of accessory proteins that mainly mediate the intracellular transport of cargoes along with the cytoskeleton. Like other cellular structures and pathways, viruses can exploit the cytoskeleton to promote different steps of their life cycle through associations with motor proteins. The complexity of the cytoskeleton and the differences among viruses, however, has led to a wide diversity of interactions, which in most cases remain poorly understood. Unveiling the details of these interactions is necessary not only for a better comprehension of specific infections, but may also reveal new potential drug targets to fight dreadful diseases such as rabies disease and acquired immunodeficiency syndrome (AIDS). In this review, we describe a few examples of the mechanisms that some human viruses, that is, rabies virus, adenovirus, herpes simplex virus, human immunodeficiency virus, influenza A virus and papillomavirus, have developed to hijack dyneins, kinesins and myosins.
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Affiliation(s)
- Clàudia Río-Bergé
- Department of Biomedical Sciences of Cells & Systems, Molecular Cell Biology Section, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Yingying Cong
- Department of Biomedical Sciences of Cells & Systems, Molecular Cell Biology Section, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Fulvio Reggiori
- Department of Biomedical Sciences of Cells & Systems, Molecular Cell Biology Section, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
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14
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Capturing the start point of the virus-cell interaction with high-speed 3D single-virus tracking. Nat Methods 2022; 19:1642-1652. [PMID: 36357694 PMCID: PMC10154077 DOI: 10.1038/s41592-022-01672-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 09/30/2022] [Indexed: 11/12/2022]
Abstract
The early stages of the virus-cell interaction have long evaded observation by existing microscopy methods due to the rapid diffusion of virions in the extracellular space and the large three-dimensional cellular structures involved. Here we present an active-feedback single-particle tracking method with simultaneous volumetric imaging of the live cell environment called 3D-TrIm to address this knowledge gap. 3D-TrIm captures the extracellular phase of the infectious cycle in what we believe is unprecedented detail. We report what are, to our knowledge, previously unobserved phenomena in the early stages of the virus-cell interaction, including skimming contact events at the millisecond timescale, orders of magnitude change in diffusion coefficient upon binding and cylindrical and linear diffusion modes along cellular protrusions. Finally, we demonstrate how this method can move single-particle tracking from simple monolayer culture toward more tissue-like conditions by tracking single virions in tightly packed epithelial cells. This multiresolution method presents opportunities for capturing fast, three-dimensional processes in biological systems.
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15
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Trim69 is a microtubule regulator that acts as a pantropic viral inhibitor. Proc Natl Acad Sci U S A 2022; 119:e2211467119. [PMID: 36251989 PMCID: PMC9618055 DOI: 10.1073/pnas.2211467119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Through a screen that combines functional and evolutionary analyses, we identified tripartite motif protein (Trim69), a poorly studied member of the Trim family, as a negative regulator of HIV-1 infection in interferon (IFN)-stimulated myeloid cells. Trim69 inhibits the early phases of infection of HIV-1, but also of HIV-2 and SIVMAC in addition to the negative and positive-strand RNA viruses vesicular stomatitis virus and severe acute respiratory syndrome coronavirus 2, with magnitudes that depend on the combination between cell type and virus. Mechanistically, Trim69 associates directly to microtubules and its antiviral activity is linked to its ability to promote the accumulation of stable microtubules, a program that we uncover to be an integral part of antiviral IFN-I responses in myeloid cells. Overall, our study identifies Trim69 as the antiviral innate defense factor that regulates the properties of microtubules to limit viral spread and highlights the cytoskeleton as an unappreciated battleground in the host-pathogen interactions that underlie viral infections.
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16
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Localization and functions of native and eGFP-tagged capsid proteins in HIV-1 particles. PLoS Pathog 2022; 18:e1010754. [PMID: 35951676 PMCID: PMC9426931 DOI: 10.1371/journal.ppat.1010754] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 08/30/2022] [Accepted: 07/21/2022] [Indexed: 12/24/2022] Open
Abstract
In infectious HIV-1 particles, the capsid protein (CA) forms a cone-shaped shell called the capsid, which encases the viral ribonucleoprotein complex (vRNP). Following cellular entry, the capsid is disassembled through a poorly understood process referred to as uncoating, which is required to release the reverse transcribed HIV-1 genome for integration into host chromatin. Whereas single virus imaging using indirect CA labeling techniques suggested uncoating to occur in the cytoplasm or at the nuclear pore, a recent study using eGFP-tagged CA reported uncoating in the nucleus. To delineate the HIV-1 uncoating site, we investigated the mechanism of eGFP-tagged CA incorporation into capsids and the utility of this fluorescent marker for visualizing HIV-1 uncoating. We find that virion incorporated eGFP-tagged CA is effectively excluded from the capsid shell, and that a subset of the tagged CA is vRNP associated. These results thus imply that eGFP-tagged CA is not a direct marker for capsid uncoating. We further show that native CA co-immunoprecipitates with vRNP components, providing a basis for retention of eGFP-tagged and untagged CA by sub-viral complexes in the nucleus. Moreover, we find that functional viral replication complexes become accessible to integrase-interacting host factors at the nuclear pore, leading to inhibition of infection and demonstrating capsid permeabilization prior to nuclear import. Finally, we find that HIV-1 cores containing a mixture of wild-type and mutant CA interact differently with cytoplasmic versus nuclear pools of the CA-binding host cofactor CPSF6. Our results suggest that capsid remodeling (including a loss of capsid integrity) is the predominant pathway for HIV-1 nuclear entry and provide new insights into the mechanism of CA retention in the nucleus via interaction with vRNP components. The timing, location and mechanisms of HIV-1 capsid disassembly which is referred to as uncoating remains unclear. Direct labeling of HIV-1 capsids, by incorporating a few green fluorescent proteins (GFP) tagged capsid protein (CA) into virions allows to image the spatio-temporal loss of HIV-1 CA during virus infection. However, the localization and functions of a few virion incorporated eGFP-tagged CA proteins remain unclear, since <50% of virus packaged CA proteins participate to form the conical capsid shell that protects the HIV-1 genome. Here we developed several approaches to test the localization and function of eGFP-tagged CA proteins in virions. We found that eGFP-tagged CA proteins are excluded from the conical capsid shell and that a subset of these proteins is associated with the viral ribonucleoprotein complex (vRNPs), through direct interactions between CA and vRNP components. eGFP-tagged CA is retained in the nucleus by virtue of vRNP association and is unlikely to report on HIV-1 capsid disassembly. We also found that HIV-1 capsids become permeabilized and are remodeled during their transport into the nucleus. Our study provides new insights into the ability of CA to interact with vRNPs for its retention in the nucleus and highlights capsid remodeling as a preferred pathway for HIV-1 entry into the nucleus.
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17
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Kim Y, Lizana L, Jeon JH. Fractal and Knot-Free Chromosomes Facilitate Nucleoplasmic Transport. PHYSICAL REVIEW LETTERS 2022; 128:038101. [PMID: 35119884 DOI: 10.1103/physrevlett.128.038101] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Accepted: 11/24/2021] [Indexed: 06/14/2023]
Abstract
Chromosomes in the nucleus assemble into hierarchies of 3D domains that, during interphase, share essential features with a knot-free condensed polymer known as the fractal globule (FG). The FG-like chromosome likely affects macromolecular transport, yet its characteristics remain poorly understood. Using computer simulations and scaling analysis, we show that the 3D folding and macromolecular size of the chromosomes determine their transport characteristics. Large-scale subdiffusion occurs at a critical particle size where the network of accessible volumes is critically connected. Condensed chromosomes have connectivity networks akin to simple Bernoulli bond percolation clusters, regardless of the polymer models. However, even if the network structures are similar, the tracer's walk dimension varies. It turns out that the walk dimension depends on the network topology of the accessible volume and dynamic heterogeneity of the tracer's hopping rate. We find that the FG structure has a smaller walk dimension than other random geometries, suggesting that the FG-like chromosome structure accelerates macromolecular diffusion and target-search.
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Affiliation(s)
- Yeonghoon Kim
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Ludvig Lizana
- Integrated Science Lab, Department of Physics, Umeå University, Umeå 90187, Sweden
| | - Jae-Hyung Jeon
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
- Asia Pacific Center for Theoretical Physics, Pohang 37673, Republic of Korea
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18
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Dynactin 1 negatively regulates HIV-1 infection by sequestering the host cofactor CLIP170. Proc Natl Acad Sci U S A 2021; 118:2102884118. [PMID: 34686593 DOI: 10.1073/pnas.2102884118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/08/2021] [Indexed: 11/18/2022] Open
Abstract
Many viruses directly engage and require the dynein-dynactin motor-adaptor complex in order to transport along microtubules (MTs) to the nucleus and initiate infection. HIV type 1 (HIV-1) exploits dynein, the dynein adaptor BICD2, and core dynactin subunits but unlike several other viruses, does not require dynactin-1 (DCTN1). The underlying reason for HIV-1's variant dynein engagement strategy and independence from DCTN1 remains unknown. Here, we reveal that DCTN1 actually inhibits early HIV-1 infection by interfering with the ability of viral cores to interact with critical host cofactors. Specifically, DCTN1 competes for binding to HIV-1 particles with cytoplasmic linker protein 170 (CLIP170), one of several MT plus-end tracking proteins (+TIPs) that regulate the stability of viral cores after entry into the cell. Outside of its function as a dynactin subunit, DCTN1 also functions as a +TIP that we find sequesters CLIP170 from incoming particles. Deletion of the Zinc knuckle (Zn) domain in CLIP170 that mediates its interactions with several proteins, including DCTN1, increased CLIP170 binding to virus particles but failed to promote infection, further suggesting that DCTN1 blocks a critical proviral function of CLIP170 mediated by its Zn domain. Our findings suggest that the unique manner in which HIV-1 binds and exploits +TIPs to regulate particle stability leaves them vulnerable to the negative effects of DCTN1 on +TIP availability and function, which may in turn have driven HIV-1 to evolve away from DCTN1 in favor of BICD2-based engagement of dynein during early infection.
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19
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Lagache T, Hanson A, Pérez-Ortega JE, Fairhall A, Yuste R. Tracking calcium dynamics from individual neurons in behaving animals. PLoS Comput Biol 2021; 17:e1009432. [PMID: 34624016 PMCID: PMC8528277 DOI: 10.1371/journal.pcbi.1009432] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 10/20/2021] [Accepted: 09/08/2021] [Indexed: 12/03/2022] Open
Abstract
Measuring the activity of neuronal populations with calcium imaging can capture emergent functional properties of neuronal circuits with single cell resolution. However, the motion of freely behaving animals, together with the intermittent detectability of calcium sensors, can hinder automatic monitoring of neuronal activity and their subsequent functional characterization. We report the development and open-source implementation of a multi-step cellular tracking algorithm (Elastic Motion Correction and Concatenation or EMC2) that compensates for the intermittent disappearance of moving neurons by integrating local deformation information from detectable neurons. We demonstrate the accuracy and versatility of our algorithm using calcium imaging data from two-photon volumetric microscopy in visual cortex of awake mice, and from confocal microscopy in behaving Hydra, which experiences major body deformation during its contractions. We quantify the performance of our algorithm using ground truth manual tracking of neurons, along with synthetic time-lapse sequences, covering a wide range of particle motions and detectability parameters. As a demonstration of the utility of the algorithm, we monitor for several days calcium activity of the same neurons in layer 2/3 of mouse visual cortex in vivo, finding significant turnover within the active neurons across days, with only few neurons that remained active across days. Also, combining automatic tracking of single neuron activity with statistical clustering, we characterize and map neuronal ensembles in behaving Hydra, finding three major non-overlapping ensembles of neurons (CB, RP1 and RP2) whose activity correlates with contractions and elongations. Our results show that the EMC2 algorithm can be used as a robust and versatile platform for neuronal tracking in behaving animals.
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Affiliation(s)
- Thibault Lagache
- Department of Biological Sciences, Columbia University, New York, New York, United States of America
- Marine Biological Laboratory, Woods Hole, Massachusetts, United States of America
| | - Alison Hanson
- Department of Biological Sciences, Columbia University, New York, New York, United States of America
- Marine Biological Laboratory, Woods Hole, Massachusetts, United States of America
- Department of Psychiatry, New York State Psychiatric Institute, Columbia University, New York, New York, United States of America
| | - Jesús E Pérez-Ortega
- Department of Biological Sciences, Columbia University, New York, New York, United States of America
| | - Adrienne Fairhall
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, United States of America
- UW Computational Neuroscience Center, University of Washington, Seattle, Washington, United States of America
| | - Rafael Yuste
- Department of Biological Sciences, Columbia University, New York, New York, United States of America
- Marine Biological Laboratory, Woods Hole, Massachusetts, United States of America
- Donostia International Physics Center, San Sebastian, Spain
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20
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Guedán A, Caroe ER, Barr GCR, Bishop KN. The Role of Capsid in HIV-1 Nuclear Entry. Viruses 2021; 13:1425. [PMID: 34452291 PMCID: PMC8402913 DOI: 10.3390/v13081425] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/16/2021] [Accepted: 07/17/2021] [Indexed: 12/19/2022] Open
Abstract
HIV-1 can infect non-dividing cells. The nuclear envelope therefore represents a barrier that HIV-1 must traverse in order to gain access to the host cell chromatin for integration. Hence, nuclear entry is a critical step in the early stages of HIV-1 replication. Following membrane fusion, the viral capsid (CA) lattice, which forms the outer face of the retroviral core, makes numerous interactions with cellular proteins that orchestrate the progress of HIV-1 through the replication cycle. The ability of CA to interact with nuclear pore proteins and other host factors around the nuclear pore determines whether nuclear entry occurs. Uncoating, the process by which the CA lattice opens and/or disassembles, is another critical step that must occur prior to integration. Both early and delayed uncoating have detrimental effects on viral infectivity. How uncoating relates to nuclear entry is currently hotly debated. Recent technological advances have led to intense discussions about the timing, location, and requirements for uncoating and have prompted the field to consider alternative uncoating scenarios that presently focus on uncoating at the nuclear pore and within the nuclear compartment. This review describes recent advances in the study of HIV-1 nuclear entry, outlines the interactions of the retroviral CA protein, and discusses the challenges of investigating HIV-1 uncoating.
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Affiliation(s)
| | | | | | - Kate N. Bishop
- Retroviral Replication Laboratory, The Francis Crick Institute, London NW1 1AT, UK; (A.G.); (E.R.C.); (G.C.R.B.)
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21
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Ritter C, Wollmann T, Lee JY, Imle A, Müller B, Fackler OT, Bartenschlager R, Rohr K. Data fusion and smoothing for probabilistic tracking of viral structures in fluorescence microscopy images. Med Image Anal 2021; 73:102168. [PMID: 34340105 DOI: 10.1016/j.media.2021.102168] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 06/10/2021] [Accepted: 07/07/2021] [Indexed: 10/20/2022]
Abstract
Automatic tracking of viral structures displayed as small spots in fluorescence microscopy images is an important task to determine quantitative information about cellular processes. We introduce a novel probabilistic approach for tracking multiple particles based on multi-sensor data fusion and Bayesian smoothing methods. The approach exploits multiple measurements as in a particle filter, both detection-based measurements and prediction-based measurements from a Kalman filter using probabilistic data association with elliptical sampling. Compared to previous probabilistic tracking methods, our approach exploits separate uncertainties for the detection-based and prediction-based measurements, and integrates them by a sequential multi-sensor data fusion method. In addition, information from both past and future time points is taken into account by a Bayesian smoothing method in conjunction with the covariance intersection algorithm for data fusion. Also, motion information based on displacements is used to improve correspondence finding. Our approach has been evaluated on data of the Particle Tracking Challenge and yielded state-of-the-art results or outperformed previous approaches. We also applied our approach to challenging time-lapse fluorescence microscopy data of human immunodeficiency virus type 1 and hepatitis C virus proteins acquired with different types of microscopes and spatial-temporal resolutions. It turned out, that our approach outperforms existing methods.
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Affiliation(s)
- C Ritter
- Biomedical Computer Vision Group, BioQuant, IPMB, Heidelberg University, Im Neuenheimer Feld 267, Heidelberg, Germany.
| | - T Wollmann
- Biomedical Computer Vision Group, BioQuant, IPMB, Heidelberg University, Im Neuenheimer Feld 267, Heidelberg, Germany
| | - J-Y Lee
- Dept. of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 344, Heidelberg, Germany; German Center for Infection Research (DZIF), Heidelberg Partner Site, Germany
| | - A Imle
- Dept. of Infectious Diseases, Integrative Virology, University Hospital Heidelberg, Im Neuenheimer Feld 344, Heidelberg, Germany; Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, Heidelberg, Germany
| | - B Müller
- Dept. of Infectious Diseases, Virology, University Hospital Heidelberg, Im Neuenheimer Feld 344, Heidelberg, Germany
| | - O T Fackler
- Dept. of Infectious Diseases, Integrative Virology, University Hospital Heidelberg, Im Neuenheimer Feld 344, Heidelberg, Germany; German Center for Infection Research (DZIF), Heidelberg Partner Site, Germany
| | - R Bartenschlager
- Dept. of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 344, Heidelberg, Germany; German Center for Infection Research (DZIF), Heidelberg Partner Site, Germany
| | - K Rohr
- Biomedical Computer Vision Group, BioQuant, IPMB, Heidelberg University, Im Neuenheimer Feld 267, Heidelberg, Germany.
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22
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Naghavi MH. HIV-1 capsid exploitation of the host microtubule cytoskeleton during early infection. Retrovirology 2021; 18:19. [PMID: 34229718 PMCID: PMC8259435 DOI: 10.1186/s12977-021-00563-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 06/29/2021] [Indexed: 01/07/2023] Open
Abstract
Microtubules (MTs) form a filamentous array that provide both structural support and a coordinated system for the movement and organization of macromolecular cargos within the cell. As such, they play a critical role in regulating a wide range of cellular processes, from cell shape and motility to cell polarization and division. The array is radial with filament minus-ends anchored at perinuclear MT-organizing centers and filament plus-ends continuously growing and shrinking to explore and adapt to the intracellular environment. In response to environmental cues, a small subset of these highly dynamic MTs can become stabilized, acquire post-translational modifications and act as specialized tracks for cargo trafficking. MT dynamics and stability are regulated by a subset of highly specialized MT plus-end tracking proteins, known as +TIPs. Central to this is the end-binding (EB) family of proteins which specifically recognize and track growing MT plus-ends to both regulate MT polymerization directly and to mediate the accumulation of a diverse array of other +TIPs at MT ends. Moreover, interaction of EB1 and +TIPs with actin-MT cross-linking factors coordinate changes in actin and MT dynamics at the cell periphery, as well as during the transition of cargos from one network to the other. The inherent structural polarity of MTs is sensed by specialized motor proteins. In general, dynein directs trafficking of cargos towards the minus-end while most kinesins direct movement toward the plus-end. As a pathogenic cargo, HIV-1 uses the actin cytoskeleton for short-range transport most frequently at the cell periphery during entry before transiting to MTs for long-range transport to reach the nucleus. While the fundamental importance of MT networks to HIV-1 replication has long been known, recent work has begun to reveal the underlying mechanistic details by which HIV-1 engages MTs after entry into the cell. This includes mimicry of EB1 by capsid (CA) and adaptor-mediated engagement of dynein and kinesin motors to elegantly coordinate early steps in infection that include MT stabilization, uncoating (conical CA disassembly) and virus transport toward the nucleus. This review discusses recent advances in our understanding of how MT regulators and their associated motors are exploited by incoming HIV-1 capsid during early stages of infection.
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Affiliation(s)
- Mojgan H Naghavi
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
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23
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AlBurtamani N, Paul A, Fassati A. The Role of Capsid in the Early Steps of HIV-1 Infection: New Insights into the Core of the Matter. Viruses 2021; 13:v13061161. [PMID: 34204384 PMCID: PMC8234406 DOI: 10.3390/v13061161] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 06/10/2021] [Accepted: 06/14/2021] [Indexed: 01/27/2023] Open
Abstract
In recent years, major advances in research and experimental approaches have significantly increased our knowledge on the role of the HIV-1 capsid in the virus life cycle, from reverse transcription to integration and gene expression. This makes the capsid protein a good pharmacological target to inhibit HIV-1 replication. This review covers our current understanding of the role of the viral capsid in the HIV-1 life cycle and its interaction with different host factors that enable reverse transcription, trafficking towards the nucleus, nuclear import and integration into host chromosomes. It also describes different promising small molecules, some of them in clinical trials, as potential targets for HIV-1 therapy.
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24
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Zila V, Margiotta E, Turoňová B, Müller TG, Zimmerli CE, Mattei S, Allegretti M, Börner K, Rada J, Müller B, Lusic M, Kräusslich HG, Beck M. Cone-shaped HIV-1 capsids are transported through intact nuclear pores. Cell 2021; 184:1032-1046.e18. [PMID: 33571428 PMCID: PMC7895898 DOI: 10.1016/j.cell.2021.01.025] [Citation(s) in RCA: 158] [Impact Index Per Article: 52.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 11/20/2020] [Accepted: 01/19/2021] [Indexed: 12/14/2022]
Abstract
Human immunodeficiency virus (HIV-1) remains a major health threat. Viral capsid uncoating and nuclear import of the viral genome are critical for productive infection. The size of the HIV-1 capsid is generally believed to exceed the diameter of the nuclear pore complex (NPC), indicating that capsid uncoating has to occur prior to nuclear import. Here, we combined correlative light and electron microscopy with subtomogram averaging to capture the structural status of reverse transcription-competent HIV-1 complexes in infected T cells. We demonstrated that the diameter of the NPC in cellulo is sufficient for the import of apparently intact, cone-shaped capsids. Subsequent to nuclear import, we detected disrupted and empty capsid fragments, indicating that uncoating of the replication complex occurs by breaking the capsid open, and not by disassembly into individual subunits. Our data directly visualize a key step in HIV-1 replication and enhance our mechanistic understanding of the viral life cycle.
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Affiliation(s)
- Vojtech Zila
- Department of Infectious Diseases, Virology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Erica Margiotta
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany; Collaboration for joint PhD degree between EMBL and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany
| | - Beata Turoňová
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany
| | - Thorsten G Müller
- Department of Infectious Diseases, Virology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Christian E Zimmerli
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany
| | - Simone Mattei
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany; Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, 8092 Zurich, Switzerland; European Molecular Biology Laboratory, Imaging Center, 69117 Heidelberg, Germany
| | - Matteo Allegretti
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany
| | - Kathleen Börner
- Department of Infectious Diseases, Virology, University of Heidelberg, 69120 Heidelberg, Germany; German Center for Infection Research, partner site Heidelberg, 69120 Heidelberg, Germany
| | - Jona Rada
- Department of Infectious Diseases, Virology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Barbara Müller
- Department of Infectious Diseases, Virology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Marina Lusic
- Department of Infectious Diseases, Virology, University of Heidelberg, 69120 Heidelberg, Germany; German Center for Infection Research, partner site Heidelberg, 69120 Heidelberg, Germany
| | - Hans-Georg Kräusslich
- Department of Infectious Diseases, Virology, University of Heidelberg, 69120 Heidelberg, Germany; German Center for Infection Research, partner site Heidelberg, 69120 Heidelberg, Germany.
| | - Martin Beck
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany; Max Planck Institute of Biophysics, Department of Molecular Sociology, 60438 Frankfurt, Germany.
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25
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Imaging Viral Infection by Fluorescence Microscopy: Focus on HIV-1 Early Stage. Viruses 2021; 13:v13020213. [PMID: 33573241 PMCID: PMC7911428 DOI: 10.3390/v13020213] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/28/2021] [Accepted: 01/28/2021] [Indexed: 12/15/2022] Open
Abstract
During the last two decades, progresses in bioimaging and the development of various strategies to fluorescently label the viral components opened a wide range of possibilities to visualize the early phase of Human Immunodeficiency Virus 1 (HIV-1) life cycle directly in infected cells. After fusion of the viral envelope with the cell membrane, the viral core is released into the cytoplasm and the viral RNA (vRNA) is retro-transcribed into DNA by the reverse transcriptase. During this process, the RNA-based viral complex transforms into a pre-integration complex (PIC), composed of the viral genomic DNA (vDNA) coated with viral and host cellular proteins. The protective capsid shell disassembles during a process called uncoating. The viral genome is transported into the cell nucleus and integrates into the host cell chromatin. Unlike biochemical approaches that provide global data about the whole population of viral particles, imaging techniques enable following individual viruses on a single particle level. In this context, quantitative microscopy has brought original data shedding light on the dynamics of the viral entry into the host cell, the cytoplasmic transport, the nuclear import, and the selection of the integration site. In parallel, multi-color imaging studies have elucidated the mechanism of action of host cell factors implicated in HIV-1 viral cycle progression. In this review, we describe the labeling strategies used for HIV-1 fluorescence imaging and report on the main advancements that imaging studies have brought in the understanding of the infection mechanisms from the viral entry into the host cell until the provirus integration step.
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26
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Rocha S, Hendrix J, Borrenberghs D, Debyser Z, Hofkens J. Imaging the Replication of Single Viruses: Lessons Learned from HIV and Future Challenges To Overcome. ACS NANO 2020; 14:10775-10783. [PMID: 32820634 DOI: 10.1021/acsnano.0c06369] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The molecular composition of viral particles indicates that a single virion is capable of initiating an infection. However, the majority of viruses that come into contact with cells fails to infect them. Understanding what makes one viral particle more successful than others requires visualizing the infection process directly in living cells, one virion at a time. In this Perspective, we explain how single-virus imaging using fluorescence microscopy can provide answers to unsolved questions in virology. We discuss fluorescent labeling of virus particles, resolution at the subviral and molecular levels, tracking in living cells, and imaging of interactions between viral and host proteins. We end this Perspective with a set of remaining questions in understanding the life cycle of retroviruses and how imaging a single virus can help researchers address these questions. Although we use examples from the HIV field, these methods are of value for the study of other viruses as well.
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Affiliation(s)
- Susana Rocha
- Molecular Imaging and Photonics, Chemistry Department, KU Leuven, B-3001 Heverlee, Flanders, Belgium
| | - Jelle Hendrix
- Molecular Imaging and Photonics, Chemistry Department, KU Leuven, B-3001 Heverlee, Flanders, Belgium
- Dynamic Bioimaging Lab, Advanced Optical Microscopy Centre and Biomedical Research Institute (BIOMED), Hasselt University, B-3590 Diepenbeek, Flanders, Belgium
| | - Doortje Borrenberghs
- Molecular Imaging and Photonics, Chemistry Department, KU Leuven, B-3001 Heverlee, Flanders, Belgium
| | - Zeger Debyser
- Laboratory for Molecular Virology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, B-3001 Heverlee, Flanders, Belgium
| | - Johan Hofkens
- Molecular Imaging and Photonics, Chemistry Department, KU Leuven, B-3001 Heverlee, Flanders, Belgium
- Max Planck Institute for Polymer Research, 55128 Mainz, Germany
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27
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Santos da Silva E, Shanmugapriya S, Malikov V, Gu F, Delaney MK, Naghavi MH. HIV-1 capsids mimic a microtubule regulator to coordinate early stages of infection. EMBO J 2020; 39:e104870. [PMID: 32896909 DOI: 10.15252/embj.2020104870] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 08/05/2020] [Accepted: 08/06/2020] [Indexed: 01/09/2023] Open
Abstract
While the microtubule end-binding protein, EB1 facilitates early stages of HIV-1 infection, how it does so remains unclear. Here, we show that beyond its effects on microtubule acetylation, EB1 also indirectly contributes to infection by delivering the plus-end tracking protein (+TIP), cytoplasmic linker protein 170 (CLIP170) to the cell periphery. CLIP170 bound to intact HIV-1 cores or in vitro assembled capsid-nucleocapsid complexes, while EB1 did not. Moreover, unlike EB1 and several other +TIPs, CLIP170 enhanced infection independently of effects on microtubule acetylation. Capsid mutants and imaging revealed that CLIP170 bound HIV-1 cores in a manner distinct from currently known capsid cofactors, influenced by pentamer composition or curvature. Structural analyses revealed an EB-like +TIP-binding motif within the capsid major homology region (MHR) that binds SxIP motifs found in several +TIPs, and variability across this MHR sequence correlated with the extent to which different retroviruses engage CLIP170 to facilitate infection. Our findings provide mechanistic insights into the complex roles of +TIPs in mediating early stages of retroviral infection, and reveal divergent capsid-based EB1 mimicry across retroviral species.
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Affiliation(s)
- Eveline Santos da Silva
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Shanmugapriya Shanmugapriya
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Viacheslav Malikov
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Feng Gu
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - M Keegan Delaney
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Mojgan H Naghavi
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
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28
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Liu YL, Perillo EP, Ang P, Kim M, Nguyen DT, Blocher K, Chen YA, Liu C, Hassan AM, Vu HT, Chen YI, Dunn AK, Yeh HC. Three-Dimensional Two-Color Dual-Particle Tracking Microscope for Monitoring DNA Conformational Changes and Nanoparticle Landings on Live Cells. ACS NANO 2020; 14:7927-7939. [PMID: 32668152 PMCID: PMC7456512 DOI: 10.1021/acsnano.9b08045] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Here, we present a three-dimensional two-color dual-particle tracking (3D-2C-DPT) technique that can simultaneously localize two spectrally distinct targets in three dimensions with a time resolution down to 5 ms. The dual-targets can be tracked with separation distances from 33 to 250 nm with tracking precisions of ∼15 nm (for static targets) and ∼35 nm (for freely diffusing targets). Since each target is individually localized, a wealth of data can be extracted, such as the relative 3D position, the 2D rotation, and the separation distance between the two targets. Using this technique, we turn a double-stranded DNA (dsDNA)-linked dumbbell-like dimer into a nanoscopic optical ruler to quantify the bending dynamics of nicked or gapped dsDNA molecules in free solution by manipulating the design of dsDNA linkers (1-nick, 3-nt, 6-nt, or 9-nt single-strand gap), and the results show the increase of kon (linear to bent) from 3.2 to 10.7 s-1. The 3D-2C-DPT is then applied to observe translational and rotational motions of the landing of an antibody-conjugated nanoparticle on the plasma membrane of living cells, revealing the reduction of rotations possibly due to interactions with membrane receptors. This study demonstrates that this 3D-2C-DPT technique is a new tool to shed light on the conformational changes of biomolecules and the intermolecular interactions on plasma membrane.
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Affiliation(s)
- Yen-Liang Liu
- Graduate Institute of Biomedical Sciences, China Medical University, No.91, Hsueh-Shih Road, Taichung 40402, Taiwan
- Center for Molecular Medicine, China Medical University, Taichung 40402, Taiwan
- Department of Biomedical Engineering, The University of Texas at Austin, 107 West Dean Keeton Street, BME Building, Austin, Texas 78712, United States
| | - Evan P Perillo
- Department of Biomedical Engineering, The University of Texas at Austin, 107 West Dean Keeton Street, BME Building, Austin, Texas 78712, United States
- Nanostring Technologies, Seattle, Washington 98109, United States
| | - Phyllis Ang
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
- Department of Computer Science, Duke University, Durham, North Carolina 27705, United States
| | - Mirae Kim
- Department of Biomedical Engineering, The University of Texas at Austin, 107 West Dean Keeton Street, BME Building, Austin, Texas 78712, United States
| | - Duc Trung Nguyen
- Department of Biomedical Engineering, The University of Texas at Austin, 107 West Dean Keeton Street, BME Building, Austin, Texas 78712, United States
| | - Katherine Blocher
- Department of Biomedical Engineering, The University of Texas at Austin, 107 West Dean Keeton Street, BME Building, Austin, Texas 78712, United States
| | - Yu-An Chen
- Department of Biomedical Engineering, The University of Texas at Austin, 107 West Dean Keeton Street, BME Building, Austin, Texas 78712, United States
| | - Cong Liu
- Department of Biomedical Engineering, The University of Texas at Austin, 107 West Dean Keeton Street, BME Building, Austin, Texas 78712, United States
| | - Ahmed M Hassan
- Department of Biomedical Engineering, The University of Texas at Austin, 107 West Dean Keeton Street, BME Building, Austin, Texas 78712, United States
| | - Huong T Vu
- Department of Biomedical Engineering, The University of Texas at Austin, 107 West Dean Keeton Street, BME Building, Austin, Texas 78712, United States
| | - Yuan-I Chen
- Department of Biomedical Engineering, The University of Texas at Austin, 107 West Dean Keeton Street, BME Building, Austin, Texas 78712, United States
| | - Andrew K Dunn
- Department of Biomedical Engineering, The University of Texas at Austin, 107 West Dean Keeton Street, BME Building, Austin, Texas 78712, United States
| | - Hsin-Chih Yeh
- Department of Biomedical Engineering, The University of Texas at Austin, 107 West Dean Keeton Street, BME Building, Austin, Texas 78712, United States
- Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, United States
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HIV-1 Exploits CLASP2 To Induce Microtubule Stabilization and Facilitate Virus Trafficking to the Nucleus. J Virol 2020; 94:JVI.00404-20. [PMID: 32376623 DOI: 10.1128/jvi.00404-20] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 04/30/2020] [Indexed: 01/01/2023] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) exploits a number of specialized microtubule (MT) plus-end tracking proteins (commonly known as +TIPs) to induce the formation of stable microtubules soon after virus entry and promote early stages of infection. However, given their functional diversity, the nature of the +TIPs involved and how they facilitate HIV-1 infection remains poorly understood. Here, we identify cytoplasmic linker-associated protein 2 (CLASP2), a +TIP that captures cortical MT plus ends to enable filament stabilization, as a host factor that enables HIV-1 to induce MT stabilization and promote early infection in natural target cell types. Using fixed- and live-cell imaging in human microglia cells, we further show that CLASP2 is required for the trafficking of incoming HIV-1 particles carrying wild-type (WT) envelope. Moreover, both WT CLASP2 and a CLASP2 mutant lacking its C-terminal domain, which mediates its interaction with several host effector proteins, bind to intact HIV-1 cores or in vitro-assembled capsid-nucleocapsid (CA-NC) complexes. However, unlike WT CLASP2, the CLASP2 C-terminal mutant is unable to induce MT stabilization or promote early HIV-1 infection. Our findings identify CLASP2 as a new host cofactor that utilizes distinct regulatory domains to bind incoming HIV-1 particles and facilitate trafficking of incoming viral cores through MT stabilization.IMPORTANCE While microtubules (MTs) have long been known to be important for delivery of incoming HIV-1 cores to the nucleus, how the virus engages and exploits these filaments remains poorly understood. Our previous work revealed the importance of highly specialized MT regulators that belong to a family called plus-end tracking proteins (+TIPs) in facilitating early stages of infection. These +TIPs perform various functions, such as engaging cargos for transport or engaging peripheral actin to stabilize MTs, suggesting several family members have the potential to contribute to infection in different ways. Here, we reveal that cytoplasmic linker-associated protein 2 (CLASP2), a key regulator of cortical capture and stabilization of MTs, interacts with incoming HIV-1 particles, and we identify a distinct C-terminal domain in CLASP2 that promotes both MT stabilization and early infection. Our findings identify a new +TIP acting as a host cofactor that facilitates early stages of viral infection.
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30
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Pietrantoni G, Ibarra-Karmy R, Arriagada G. Microtubule Retrograde Motors and Their Role in Retroviral Transport. Viruses 2020; 12:v12040483. [PMID: 32344581 PMCID: PMC7232228 DOI: 10.3390/v12040483] [Citation(s) in RCA: 4] [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: 03/16/2020] [Revised: 04/18/2020] [Accepted: 04/22/2020] [Indexed: 12/16/2022] Open
Abstract
Following entry into the host cell, retroviruses generate a dsDNA copy of their genomes via reverse transcription, and this viral DNA is subsequently integrated into the chromosomal DNA of the host cell. Before integration can occur, however, retroviral DNA must be transported to the nucleus as part of a ‘preintegration complex’ (PIC). Transporting the PIC through the crowded environment of the cytoplasm is challenging, and retroviruses have evolved different mechanisms to accomplish this feat. Within a eukaryotic cell, microtubules act as the roads, while the microtubule-associated proteins dynein and kinesin are the vehicles that viruses exploit to achieve retrograde and anterograde trafficking. This review will examine the various mechanisms retroviruses have evolved in order to achieve retrograde trafficking, confirming that each retrovirus has its own strategy to functionally subvert microtubule associated proteins.
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31
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Fernandez J, Arhel NJ. [Transportin-1 orchestrates HIV-1 uncoating and nuclear entry]. Med Sci (Paris) 2020; 36:203-206. [PMID: 32228833 DOI: 10.1051/medsci/2020031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Affiliation(s)
- Juliette Fernandez
- Institut de recherche en infectiologie de Montpellier (IRIM), Université de Montpellier, CNRS, 1919 route de Mende, 34293 Montpellier, France
| | - Nathalie J Arhel
- Institut de recherche en infectiologie de Montpellier (IRIM), Université de Montpellier, CNRS, 1919 route de Mende, 34293 Montpellier, France
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32
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Ingram Z, Taylor M, Okland G, Martin R, Hulme AE. Characterization of HIV-1 uncoating in human microglial cell lines. Virol J 2020; 17:31. [PMID: 32143686 PMCID: PMC7060623 DOI: 10.1186/s12985-020-01301-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 02/21/2020] [Indexed: 12/17/2022] Open
Abstract
Background After viral fusion with the cell membrane, the conical capsid of HIV-1 disassembles by a process called uncoating. Previously we have utilized the CsA washout assay, in which TRIM-CypA mediated restriction of viral replication is used to detect the state of the viral capsid, to study the kinetics of HIV-1 uncoating in owl monkey kidney (OMK) and HeLa cells. Here we have extended this analysis to the human microglial cell lines CHME3 and C20 to characterize uncoating in a cell type that is a natural target of HIV infection. Methods The CsA washout was used to characterize uncoating of wildtype and capsid mutant viruses in CHME3 and C20 cells. Viral fusion assays and nevirapine addition assays were performed to relate the kinetics of viral fusion and reverse transcription to uncoating. Results We found that uncoating initiated within the first hour after viral fusion and was facilitated by reverse transcription in CHME3 and C20 cells. The capsid mutation A92E did not significantly alter uncoating kinetics. Viruses with capsid mutations N74D and E45A decreased the rate of uncoating in CHME3 cells, but did not alter reverse transcription. Interestingly, the second site suppressor capsid mutation R132T was able to rescue the uncoating kinetics of the E45A mutation, despite having a hyperstable capsid. Conclusions These results are most similar to previously observed characteristics of uncoating in HeLa cells and support the model in which uncoating is initiated by early steps of reverse transcription in the cytoplasm. A comparison of the uncoating kinetics of CA mutant viruses in OMK and CHME3 cells reveals the importance of cellular factors in the process of uncoating. The E45A/R132T mutant virus specifically suggests that disrupted interactions with cellular factors, rather than capsid stability, is responsible for the delayed uncoating kinetics seen in E45A mutant virus. Future studies aimed at identifying these factors will be important for understanding the process of uncoating and the development of interventions to disrupt this process.
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Affiliation(s)
- Zachary Ingram
- Department of Biomedical Sciences, Missouri State University, Springfield, MO, USA
| | - Melanie Taylor
- Department of Biomedical Sciences, Missouri State University, Springfield, MO, USA
| | - Glister Okland
- Department of Biomedical Sciences, Missouri State University, Springfield, MO, USA
| | - Richard Martin
- Department of Biomedical Sciences, Missouri State University, Springfield, MO, USA
| | - Amy E Hulme
- Department of Biomedical Sciences, Missouri State University, Springfield, MO, USA.
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33
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Sannier G, Dubé M, Kaufmann DE. Single-Cell Technologies Applied to HIV-1 Research: Reaching Maturity. Front Microbiol 2020; 11:297. [PMID: 32194526 PMCID: PMC7064469 DOI: 10.3389/fmicb.2020.00297] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 02/10/2020] [Indexed: 12/11/2022] Open
Abstract
The need for definitive answers probably explains our natural tendency to seek simplicity. The reductionist “bulk” approach, in which a mean behavior is attributed to a heterogeneous cell population, fulfills this need by considerably helping the conceptualization of complex biological processes. However, the limits of this methodology are becoming increasingly clear as models seek to explain biological events occurring in vivo, where heterogeneity is the rule. Research in the HIV-1 field is no exception: the challenges encountered in the development of preventive and curative anti-HIV-1 strategies may well originate in part from inadequate assumptions built on bulk technologies, highlighting the need for new perspectives. The emergence of diverse single-cell technologies set the stage for potential breakthrough discoveries, as heterogeneous processes can now be investigated with an unprecedented depth in topics as diverse as HIV-1 tropism, dynamics of the replication cycle, latency, viral reservoirs and immune control. In this review, we summarize recent advances in the HIV-1 field made possible by single-cell technologies, and contextualize their importance.
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Affiliation(s)
- Gérémy Sannier
- Research Centre of the Centre Hospitalier de l'Université de Montréal (CRCHUM), Montreal, QC, Canada.,Department of Microbiology, Infectiology and Immunology, Université de Montréal, Montreal, QC, Canada
| | - Mathieu Dubé
- Research Centre of the Centre Hospitalier de l'Université de Montréal (CRCHUM), Montreal, QC, Canada
| | - Daniel E Kaufmann
- Research Centre of the Centre Hospitalier de l'Université de Montréal (CRCHUM), Montreal, QC, Canada.,Department of Medicine, Université de Montréal, Montreal, QC, Canada.,Consortium for HIV/AIDS Vaccine Development (Scripps CHAVD), La Jolla, CA, United States
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34
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Liu SL, Wang ZG, Xie HY, Liu AA, Lamb DC, Pang DW. Single-Virus Tracking: From Imaging Methodologies to Virological Applications. Chem Rev 2020; 120:1936-1979. [PMID: 31951121 PMCID: PMC7075663 DOI: 10.1021/acs.chemrev.9b00692] [Citation(s) in RCA: 100] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
![]()
Uncovering
the mechanisms of virus infection and assembly is crucial
for preventing the spread of viruses and treating viral disease. The
technique of single-virus tracking (SVT), also known as single-virus
tracing, allows one to follow individual viruses at different parts
of their life cycle and thereby provides dynamic insights into fundamental
processes of viruses occurring in live cells. SVT is typically based
on fluorescence imaging and reveals insights into previously unreported
infection mechanisms. In this review article, we provide the readers
a broad overview of the SVT technique. We first summarize recent advances
in SVT, from the choice of fluorescent labels and labeling strategies
to imaging implementation and analytical methodologies. We then describe
representative applications in detail to elucidate how SVT serves
as a valuable tool in virological research. Finally, we present our
perspectives regarding the future possibilities and challenges of
SVT.
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Affiliation(s)
- Shu-Lin Liu
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Center for Analytical Sciences, College of Chemistry, and School of Medicine , Nankai University , Tianjin 300071 , P. R. China.,Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry , China University of Geosciences , Wuhan 430074 , P. R. China
| | - Zhi-Gang Wang
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Center for Analytical Sciences, College of Chemistry, and School of Medicine , Nankai University , Tianjin 300071 , P. R. China
| | - Hai-Yan Xie
- School of Life Science , Beijing Institute of Technology , Beijing 100081 , P. R. China
| | - An-An Liu
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Center for Analytical Sciences, College of Chemistry, and School of Medicine , Nankai University , Tianjin 300071 , P. R. China
| | - Don C Lamb
- Physical Chemistry, Department of Chemistry, Center for Nanoscience (CeNS), and Center for Integrated Protein Science Munich (CIPSM) and Nanosystems Initiative Munich (NIM) , Ludwig-Maximilians-Universität , München , 81377 , Germany
| | - Dai-Wen Pang
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Center for Analytical Sciences, College of Chemistry, and School of Medicine , Nankai University , Tianjin 300071 , P. R. China.,College of Chemistry and Molecular Sciences, State Key Laboratory of Virology, The Institute for Advanced Studies, and Wuhan Institute of Biotechnology , Wuhan University , Wuhan 430072 , P. R. China
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35
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Huang PT, Summers BJ, Xu C, Perilla JR, Malikov V, Naghavi MH, Xiong Y. FEZ1 Is Recruited to a Conserved Cofactor Site on Capsid to Promote HIV-1 Trafficking. Cell Rep 2019; 28:2373-2385.e7. [PMID: 31422020 PMCID: PMC6736649 DOI: 10.1016/j.celrep.2019.07.079] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Revised: 05/08/2019] [Accepted: 07/22/2019] [Indexed: 12/31/2022] Open
Abstract
HIV-1 uses the microtubule network to traffic the viral capsid core toward the nucleus. Viral nuclear trafficking and infectivity require the kinesin-1 adaptor protein FEZ1. Here, we demonstrate that FEZ1 directly interacts with the HIV-1 capsid and specifically binds capsid protein (CA) hexamers. FEZ1 contains multiple acidic, poly-glutamate stretches that interact with the positively charged central pore of CA hexamers. The FEZ1-capsid interaction directly competes with nucleotides and inositol hexaphosphate (IP6) that bind at the same location. In addition, all-atom molecular dynamic (MD) simulations establish the molecular details of FEZ1-capsid interactions. Functionally, mutation of the FEZ1 capsid-interacting residues significantly reduces trafficking of HIV-1 particles toward the nucleus and early infection. These findings support a model in which the central capsid hexamer pore is a general HIV-1 cofactor-binding hub and FEZ1 serves as a unique CA hexamer pattern sensor to recognize this site and promote capsid trafficking in the cell.
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Affiliation(s)
- Pei-Tzu Huang
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Brady James Summers
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Chaoyi Xu
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
| | - Juan R Perilla
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
| | - Viacheslav Malikov
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Mojgan H Naghavi
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Yong Xiong
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA.
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36
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Hillman C, Stewart PE, Strnad M, Stone H, Starr T, Carmody A, Evans TJ, Carracoi V, Wachter J, Rosa PA. Visualization of Spirochetes by Labeling Membrane Proteins With Fluorescent Biarsenical Dyes. Front Cell Infect Microbiol 2019; 9:287. [PMID: 31482073 PMCID: PMC6710359 DOI: 10.3389/fcimb.2019.00287] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 07/24/2019] [Indexed: 01/06/2023] Open
Abstract
Numerous methods exist for fluorescently labeling proteins either as direct fusion proteins (GFP, RFP, YFP, etc.—attached to the protein of interest) or utilizing accessory proteins to produce fluorescence (SNAP-tag, CLIP-tag), but the significant increase in size that these accompanying proteins add may hinder or impede proper protein folding, cellular localization, or oligomerization. Fluorescently labeling proteins with biarsenical dyes, like FlAsH, circumvents this issue by using a short 6-amino acid tetracysteine motif that binds the membrane-permeable dye and allows visualization of living cells. Here, we report the successful adaptation of FlAsH dye for live-cell imaging of two genera of spirochetes, Leptospira and Borrelia, by labeling inner or outer membrane proteins tagged with tetracysteine motifs. Visualization of labeled spirochetes was possible by fluorescence microscopy and flow cytometry. A subsequent increase in fluorescent signal intensity, including prolonged detection, was achieved by concatenating two copies of the 6-amino acid motif. Overall, we demonstrate several positive attributes of the biarsenical dye system in that the technique is broadly applicable across spirochete genera, the tetracysteine motif is stably retained and does not interfere with protein function throughout the B. burgdorferi infectious cycle, and the membrane-permeable nature of the dyes permits fluorescent detection of proteins in different cellular locations without the need for fixation or permeabilization. Using this method, new avenues of investigation into spirochete morphology and motility, previously inaccessible with large fluorescent proteins, can now be explored.
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Affiliation(s)
- Chadwick Hillman
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, United States
| | - Philip E Stewart
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, United States
| | - Martin Strnad
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, United States.,Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czechia.,Faculty of Science, University of South Bohemia in České Budějovice, České Budějovice, Czechia
| | - Hunter Stone
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, United States
| | - Tregei Starr
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, United States
| | - Aaron Carmody
- Research Technologies Section, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, United States
| | - Tyler J Evans
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, United States
| | - Valentina Carracoi
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, United States
| | - Jenny Wachter
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, United States
| | - Patricia A Rosa
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, United States
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Dissecting the Cell Entry Pathway of Baculovirus by Single-Particle Tracking and Quantitative Electron Microscopic Analysis. J Virol 2019; 93:JVI.00033-19. [PMID: 30760565 DOI: 10.1128/jvi.00033-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 02/05/2019] [Indexed: 02/07/2023] Open
Abstract
The budded virus of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) infects insect cells through mainly clathrin-mediated endocytosis. However, the cell entry pathway of AcMNPV remains unclear. In this study, by using population-based analysis of single-virus tracking and electron microscopy, we investigated the internalization, fusion behavior, and endocytic trafficking of AcMNPV. AcMNPV internalization into host insect cells was facilitated by actin polymerization and dynamin. After incorporation into early endosomes, the AcMNPV envelope fused with the membranes of early endosome, allowing for nucleocapsid release into the cytoplasm. Microtubules were implicated in the bidirectional and long-range transport of virus-containing endosomes. In addition, microtubule depolymerization reduced the motility of virus-bearing early endosomes, impairing the progression of infection beyond enlarged early endosomes. These findings demonstrated that AcMNPV internalization was facilitated by actin polymerization in a dynamin-dependent manner, and nucleocapsid release occurred in early endosomes in a microtubule-dependent manner. This study provides mechanistic and kinetic insights into AcMNPV infection and enhance our understanding of the infection pathway of baculoviruses.IMPORTANCE Baculoviruses are used widely as environmentally benign pesticides, protein expression systems, and potential mammalian gene delivery vectors. Despite the significant application value, little is known about the cell entry and endocytic trafficking pathways of baculoviruses. In this study, we demonstrated that the alphabaculovirus AcMNPV exhibited actin- and microtubule-dependent transport for nucleocapsid release predominantly from within early endosomes. In contrast to AcMNPV transduction in mammalian cells, its infection in host insect cells is facilitated by actin polymerization for internalization and microtubules for endocytic trafficking within early endosomes, implying that AcMNPV exhibits cell type specificity in the requirement of the cytoskeleton network. In addition, experimental depolymerization of microtubules impaired the progression of infection beyond enlarged early endosomes. This is the first study that dissects the cell entry pathway of baculoviruses in host cells at the single-particle level, which advances our understanding of the early steps of baculovirus entry.
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Xie J, Mei L, Sun Y, Yong X, Han N, Dai J, Yang X, Ruan G. Direct and Noninvasive Penetration of Bare Hydrophobic Quantum Dots through Live Cell Membranes. ACS Biomater Sci Eng 2019; 5:468-477. [PMID: 33405812 DOI: 10.1021/acsbiomaterials.8b01246] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Semiconductor quantum dots (QDs) possess outstanding optical properties as fluorescent probes, but their applications in live cell intracellular imaging are hindered by various cellular transport barriers. Inspired by membrane proteins inserting their nanometer-scale hydrophobic surface into biomembranes, the present work aims to investigate the possibility that bare hydrophobic QDs could penetrate through live cell membranes without disrupting the membrane integrity. We utilize live cell spinning disk confocal microscopy to image and track the cellular transport process of bare hydrophobic QDs in the presence of a small percentage of three different organic cosolvents, namely, tetrahydrofuran (THF), chloroform, and hexane. A major finding is that, under certain cosolvent conditions, bare hydrophobic QDs can indeed penetrate through biomembranes in a noninvasive manner. Results of this work offer us guidance to design a new class of nanobioprobes based on combining hydrophobic nanoscale surface and cosolvent, and they provide key new pieces to the emerging complex and sophisticated picture of nanostructure-biosystem interactions.
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Affiliation(s)
- Jinbing Xie
- Department of Biomedical Engineering, College of Engineering and Applied Sciences, Nanjing University, 16 Jinyin Street, Nanjing, Jiangsu 210093, China.,Institute of Materials Engineering, College of Engineering and Applied Sciences, Nanjing University, 16 Jinyin Street, Nanjing, Jiangsu 210093, China.,Collaborative Innovation Center of Chemistry for Life Sciences, Nanjing University, 163 Xianlin Road, Nanjing, Jiangsu, 210023 China
| | - Ling Mei
- Department of Biomedical Engineering, College of Engineering and Applied Sciences, Nanjing University, 16 Jinyin Street, Nanjing, Jiangsu 210093, China.,Institute of Materials Engineering, College of Engineering and Applied Sciences, Nanjing University, 16 Jinyin Street, Nanjing, Jiangsu 210093, China.,Collaborative Innovation Center of Chemistry for Life Sciences, Nanjing University, 163 Xianlin Road, Nanjing, Jiangsu, 210023 China
| | - Yuxiang Sun
- Department of Biomedical Engineering, College of Engineering and Applied Sciences, Nanjing University, 16 Jinyin Street, Nanjing, Jiangsu 210093, China.,Institute of Materials Engineering, College of Engineering and Applied Sciences, Nanjing University, 16 Jinyin Street, Nanjing, Jiangsu 210093, China.,Collaborative Innovation Center of Chemistry for Life Sciences, Nanjing University, 163 Xianlin Road, Nanjing, Jiangsu, 210023 China
| | - Xueqing Yong
- Department of Biomedical Engineering, College of Engineering and Applied Sciences, Nanjing University, 16 Jinyin Street, Nanjing, Jiangsu 210093, China.,Institute of Materials Engineering, College of Engineering and Applied Sciences, Nanjing University, 16 Jinyin Street, Nanjing, Jiangsu 210093, China.,Collaborative Innovation Center of Chemistry for Life Sciences, Nanjing University, 163 Xianlin Road, Nanjing, Jiangsu, 210023 China
| | - Ning Han
- Department of Biomedical Engineering, College of Engineering and Applied Sciences, Nanjing University, 16 Jinyin Street, Nanjing, Jiangsu 210093, China.,Institute of Materials Engineering, College of Engineering and Applied Sciences, Nanjing University, 16 Jinyin Street, Nanjing, Jiangsu 210093, China.,Collaborative Innovation Center of Chemistry for Life Sciences, Nanjing University, 163 Xianlin Road, Nanjing, Jiangsu, 210023 China
| | - Jie Dai
- Department of Biomedical Engineering, College of Engineering and Applied Sciences, Nanjing University, 16 Jinyin Street, Nanjing, Jiangsu 210093, China.,Institute of Materials Engineering, College of Engineering and Applied Sciences, Nanjing University, 16 Jinyin Street, Nanjing, Jiangsu 210093, China.,Collaborative Innovation Center of Chemistry for Life Sciences, Nanjing University, 163 Xianlin Road, Nanjing, Jiangsu, 210023 China
| | - Xuan Yang
- Department of Biomedical Engineering, College of Engineering and Applied Sciences, Nanjing University, 16 Jinyin Street, Nanjing, Jiangsu 210093, China.,Institute of Materials Engineering, College of Engineering and Applied Sciences, Nanjing University, 16 Jinyin Street, Nanjing, Jiangsu 210093, China.,Collaborative Innovation Center of Chemistry for Life Sciences, Nanjing University, 163 Xianlin Road, Nanjing, Jiangsu, 210023 China
| | - Gang Ruan
- Department of Biomedical Engineering, College of Engineering and Applied Sciences, Nanjing University, 16 Jinyin Street, Nanjing, Jiangsu 210093, China.,Institute of Materials Engineering, College of Engineering and Applied Sciences, Nanjing University, 16 Jinyin Street, Nanjing, Jiangsu 210093, China.,Collaborative Innovation Center of Chemistry for Life Sciences, Nanjing University, 163 Xianlin Road, Nanjing, Jiangsu, 210023 China
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Quantitative monitoring of the cytoplasmic release of NCp7 proteins from individual HIV-1 viral cores during the early steps of infection. Sci Rep 2019; 9:945. [PMID: 30700731 PMCID: PMC6353972 DOI: 10.1038/s41598-018-37150-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 11/29/2018] [Indexed: 12/15/2022] Open
Abstract
Fluorescence microscopy imaging of individual HIV-1 viruses necessitates a specific labeling of viral structures that minimally perturbs the infection process. Herein, we used HIV-1 pseudoviruses containing NCp7 fused to a tetracystein (TC) tag, labeled by a biarsenical fluorescein derivative (FlAsH) to quantitatively monitor the NCp7 protein concentration in the viral cores during the early stages of infection. Single particle imaging of individual pseudoviruses with defined ratios of TC-tagged to non tagged NCp7 proteins, together with theoretical modeling of energy transfer between FlAsH dyes, showed that the high packaging of TC-tagged proteins in the viral cores causes a strong fluorescence quenching of FlAsH and that the fluorescence intensity of individual viral complexes is an appropriate parameter to monitor changes in the amount of NCp7 molecules within the viral particles during infection. Interestingly, we observed a dramatic fluorescence increase of individual FlAsH-labeled pseudoviruses containing 100% TC-tagged NCp7 proteins in infected cells at 8 and 16 h post-infection. This effect was significantly lower for pseudoviruses expressing TC-tagged integrase. Therefore, this fluorescence increase is likely related to the cytoplasmic viral transformation and the release of NCp7 molecules from the viral complexes. This loss of quenching effect is largely reduced when reverse transcriptase is inhibited, showing that NCp7 release is connected to viral DNA synthesis. A spatial analysis further revealed that NCp7-TC release is more pronounced in the perinuclear space, where capsid disassembly is thought to be completed. Quantification of NCp7-TC content based on fluorescence quenching presented in this study evidences for the first time the cytoplasmic release of NCp7 during the remodeling of HIV-1 viral particles on their journey toward the nucleus. The developed approach can be applied to quantify dye concentrations in a wide range of nano-objects by fluorescence microscopy techniques.
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40
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Nathan L, Daniel S. Single Virion Tracking Microscopy for the Study of Virus Entry Processes in Live Cells and Biomimetic Platforms. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1215:13-43. [PMID: 31317494 PMCID: PMC7122913 DOI: 10.1007/978-3-030-14741-9_2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The most widely-used assays for studying viral entry, including infectivity, cofloatation, and cell-cell fusion assays, yield functional information but provide low resolution of individual entry steps. Structural characterization provides high-resolution conformational information, but on its own is unable to address the functional significance of these conformations. Single virion tracking microscopy techniques provide more detail on the intermediate entry steps than infection assays and more functional information than structural methods, bridging the gap between these methods. In addition, single virion approaches also provide dynamic information about the kinetics of entry processes. This chapter reviews single virion tracking techniques and describes how they can be applied to study specific virus entry steps. These techniques provide information complementary to traditional ensemble approaches. Single virion techniques may either probe virion behavior in live cells or in biomimetic platforms. Synthesizing information from ensemble, structural, and single virion techniques ultimately yields a more complete understanding of the viral entry process than can be achieved by any single method alone.
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Affiliation(s)
- Lakshmi Nathan
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, USA.
| | - Susan Daniel
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, USA.
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41
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RanBP2 regulates the anti-retroviral activity of TRIM5α by SUMOylation at a predicted phosphorylated SUMOylation motif. Commun Biol 2018; 1:193. [PMID: 30456314 PMCID: PMC6237768 DOI: 10.1038/s42003-018-0198-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 10/19/2018] [Indexed: 01/30/2023] Open
Abstract
TRIM5α is a cytoplasmic restriction factor that blocks post-entry retroviral infection. Evidence suggests that its antiviral activity can be regulated by SUMO, but how this is achieved remains unknown. Here, we show that TRIM5α forms a complex with RanGAP1, Ubc9, and RanBP2 at the nuclear pore, and that RanBP2 E3 SUMO ligase promotes the SUMOylation of endogenous TRIM5α in the cytoplasm. Loss of RanBP2 blocked SUMOylation of TRIM5α, altered its localization in primary cells, and suppressed the antiviral activity of both rhesus and human orthologs. In cells, human TRIM5α is modified on K84 within a predicted phosphorylated SUMOylation motif (pSUM) and not on K10 as found in vitro. Non-modified TRIM5α lacked antiviral activity, indicating that only SUMOylated TRIM5α acts as a restriction factor. This work illustrates the importance of the nuclear pore in intrinsic antiviral immunity, acting as a hub where virus, SUMO machinery, and restriction factors can meet. Ghizlane Maarifi et al. demonstrate that a nuclear pore component, RanBP2, SUMOylates the retroviral restriction factor TRIM5α to promote its antiviral activity. This study suggests an unexpected role of the nuclear pore for regulating anti-viral innate immunity.
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42
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Francis AC, Melikyan GB. Single HIV-1 Imaging Reveals Progression of Infection through CA-Dependent Steps of Docking at the Nuclear Pore, Uncoating, and Nuclear Transport. Cell Host Microbe 2018; 23:536-548.e6. [PMID: 29649444 DOI: 10.1016/j.chom.2018.03.009] [Citation(s) in RCA: 121] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 02/03/2018] [Accepted: 03/16/2018] [Indexed: 11/26/2022]
Abstract
The HIV-1 core consists of capsid proteins (CA) surrounding viral genomic RNA. After virus-cell fusion, the core enters the cytoplasm and the capsid shell is lost through uncoating. CA loss precedes nuclear import and HIV integration into the host genome, but the timing and location of uncoating remain unclear. By visualizing single HIV-1 infection, we find that CA is required for core docking at the nuclear envelope (NE), whereas early uncoating in the cytoplasm promotes proteasomal degradation of viral complexes. Only docked cores exhibiting accelerated loss of CA at the NE enter the nucleus. Interestingly, a CA mutation (N74D) altering virus engagement of host factors involved in nuclear transport does not alter the uncoating site at the NE but reduces the nuclear penetration depth. Thus, CA protects HIV-1 complexes from degradation, mediates docking at the nuclear pore before uncoating, and determines the depth of nuclear penetration en route to integration.
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Affiliation(s)
| | - Gregory B Melikyan
- Department of Pediatrics, Emory University, Atlanta, GA 30322, USA; Children's Healthcare of Atlanta, Atlanta, GA 30322, USA.
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43
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Sharma KK, Marzinek JK, Tantirimudalige SN, Bond PJ, Wohland T. Single-molecule studies of flavivirus envelope dynamics: Experiment and computation. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2018; 143:38-51. [PMID: 30223001 DOI: 10.1016/j.pbiomolbio.2018.09.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 09/06/2018] [Accepted: 09/11/2018] [Indexed: 12/11/2022]
Abstract
Flaviviruses are simple enveloped viruses exhibiting complex structural and functional heterogeneities. Decades of research have provided crucial basic insights, antiviral medication and moderately successful gene therapy trials. The most infectious particle is, however, not always the most abundant one in a population, questioning the utility of classic ensemble-averaging virology approaches. Indeed, viral replication is often not particularly efficient, prone to errors or containing parallel routes. Here, we review different single-molecule sensitive fluorescence methods that are employed to investigate flaviviruses. In particular, we review how (i) time-resolved Förster resonance energy transfer (trFRET) was applied to probe dengue envelope conformations; (ii) FRET-fluorescence correlation spectroscopy to investigate dengue envelope intrinsic dynamics and (iii) single particle tracking to follow the path of dengue viruses in cells. We also discuss how such methods may be supported by molecular dynamics (MD) simulations over a range of spatio-temporal scales, to provide complementary data on the structure and dynamics of flaviviral systems. We describe recent improvements in multiscale MD approaches that allowed the simulation of dengue particle envelopes in near-atomic resolution. We hope this review is an incentive for setting up and applying similar single-molecule studies and combine them with MD simulations to investigate structural dynamics of entire flavivirus particles over the nanosecond-to-millisecond time-scale and follow viruses during infection in cells over milliseconds to minutes.
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Affiliation(s)
- Kamal Kant Sharma
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
| | - Jan K Marzinek
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore; Bioinformatics Institute (A*STAR), 30 Biopolis Street, #07-01 Matrix, Singapore 138671, Singapore
| | - Sarala Neomi Tantirimudalige
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
| | - Peter J Bond
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore; Bioinformatics Institute (A*STAR), 30 Biopolis Street, #07-01 Matrix, Singapore 138671, Singapore.
| | - Thorsten Wohland
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore; Department of Chemistry, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore; Centre for Bioimaging Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117557, Singapore.
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44
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Abstract
Recent studies show that human immunodeficiency virus type 1 (HIV-1) can utilize microtubules and their associated proteins to complete key postfusion steps during infection. These include associating with both dynein and kinesin motors, as well as proteins, which enhance infection by altering microtubule dynamics during infection. In this article, we will discuss findings on how dynein and kinesin motors, as well as other microtubule-associated proteins, influence HIV-1 trafficking, viral core uncoating, and nuclear import of the viral ribonucleoprotein (RNP).
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45
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Walsh D, Naghavi MH. Exploitation of Cytoskeletal Networks during Early Viral Infection. Trends Microbiol 2018; 27:39-50. [PMID: 30033343 DOI: 10.1016/j.tim.2018.06.008] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 06/12/2018] [Accepted: 06/29/2018] [Indexed: 12/12/2022]
Abstract
Being dependent upon host transport systems to navigate the cytoplasm, viruses have evolved various strategies to manipulate cytoskeletal functions. Generally, viruses use the actin cytoskeleton to control entry and short-range transport at the cell periphery and exploit microtubules (MTs) for longer-range cytosolic transport, in some cases to reach the nucleus. While earlier studies established the fundamental importance of these networks to successful infection, the mechanistic details and true extent to which viruses usurp highly specialized host cytoskeletal regulators and motor adaptors is only beginning to emerge. This review outlines our current understanding of how cytoskeletal regulation contributes specifically to the early stages of viral infection, with a primary focus on retroviruses and herpesviruses as examples of recent advances in this area.
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Affiliation(s)
- Derek Walsh
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Mojgan H Naghavi
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
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46
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Lysova I, Spiegelhalter C, Réal E, Zgheib S, Anton H, Mély Y. ReAsH/tetracystein-based correlative light-electron microscopy for HIV-1 imaging during the early stages of infection. Methods Appl Fluoresc 2018; 6:045001. [PMID: 29938685 DOI: 10.1088/2050-6120/aacec1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Visualization of viruses in the host cell during the course of infection by correlative light-electron microscopy (CLEM) requires a specific labelling of the viral structures in order to recognize the nanometric viral cores in the intracellular environment. For Human immunodeficiency virus type 1 (HIV-1), the labelling approaches developed for fluorescence microscopy are generally not suited for transmission electron microscopy (TEM), so that imaging of HIV-1 particles in infected cells by CLEM is not straightforward. Herein, we adapt the labeling approach with a tetracystein tag (TC) and a biarsenical resorufin-based label (ReAsH) for monitoring the HIV-1 particles during the early stages of HIV-1 infection by CLEM. In this approach, the ReAsH fluorophore triggers the photo-conversion of 3,3-diaminobenzidine tetrahydrochloride (DAB), generating a precipitate sensitive to osmium tetroxide staining that can be visualized by transmission electron microscopy. The TC tag is fused to the nucleocapsid protein NCp7, a nucleic acid chaperone that binds to the viral genome. HeLa cells, infected by ReAsH-labeled pseudoviruses containg NCp7-TC proteins exhibit strong fluorescent cytoplasmic spots that overlap with dark precipitates in the TEM sections. The DAB precipitates corresponding to single viral cores are observed all over the cytoplasm, and notably near microtubules and nuclear pores. This work describes for the first time a specific contrast given by HIV-1 viral proteins in TEM images and opens new perspectives for the use of CLEM to monitor the intracellular traffic of viral complexes.
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Affiliation(s)
- Iryna Lysova
- Laboratoire de Bioimagerie et Pathologies, CNRS UMR 7021, Strasbourg University, Faculty of Pharmacy, 74 route du Rhin, Illkirch, France
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47
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Localized Phosphorylation of a Kinesin-1 Adaptor by a Capsid-Associated Kinase Regulates HIV-1 Motility and Uncoating. Cell Rep 2018; 20:2792-2799. [PMID: 28930676 DOI: 10.1016/j.celrep.2017.08.076] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 06/08/2017] [Accepted: 08/23/2017] [Indexed: 12/28/2022] Open
Abstract
Although microtubule motors mediate intracellular virus transport, the underlying interactions and control mechanisms remain poorly defined. This is particularly true for HIV-1 cores, which undergo complex, interconnected processes of cytosolic transport, reverse transcription, and uncoating of the capsid shell. Although kinesins have been implicated in regulating these events, curiously, there are no direct kinesin-core interactions. We recently showed that the capsid-associated kinesin-1 adaptor protein, fasciculation and elongation protein zeta-1 (FEZ1), regulates HIV-1 trafficking. Here, we show that FEZ1 and kinesin-1 heavy, but not light, chains regulate not only HIV-1 transport but also uncoating. This required FEZ1 phosphorylation, which controls its interaction with kinesin-1. HIV-1 did not stimulate widespread FEZ1 phosphorylation but, instead, bound microtubule (MT) affinity-regulating kinase 2 (MARK2) to stimulate FEZ1 phosphorylation on viral cores. Our findings reveal that HIV-1 binds a regulatory kinase to locally control kinesin-1 adaptor function on viral cores, thereby regulating both particle motility and uncoating.
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48
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Live-Cell Imaging of Early Steps of Single HIV-1 Infection. Viruses 2018; 10:v10050275. [PMID: 29783762 PMCID: PMC5977268 DOI: 10.3390/v10050275] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 05/15/2018] [Accepted: 05/18/2018] [Indexed: 01/10/2023] Open
Abstract
Live-cell imaging of single HIV-1 entry offers a unique opportunity to delineate the spatio-temporal regulation of infection. Novel virus labeling and imaging approaches enable the visualization of key steps of HIV-1 entry leading to nuclear import, integration into the host genome, and viral protein expression. Here, we discuss single virus imaging strategies, focusing on live-cell imaging of single virus fusion and productive uncoating that culminates in HIV-1 infection.
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49
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Parveen N, Borrenberghs D, Rocha S, Hendrix J. Single Viruses on the Fluorescence Microscope: Imaging Molecular Mobility, Interactions and Structure Sheds New Light on Viral Replication. Viruses 2018; 10:E250. [PMID: 29748498 PMCID: PMC5977243 DOI: 10.3390/v10050250] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 04/24/2018] [Accepted: 05/04/2018] [Indexed: 12/13/2022] Open
Abstract
Viruses are simple agents exhibiting complex reproductive mechanisms. Decades of research have provided crucial basic insights, antiviral medication and moderately successful gene therapy trials. The most infectious viral particle is, however, not always the most abundant one in a population, questioning the utility of classic ensemble-averaging virology. Indeed, viral replication is often not particularly efficient, prone to errors or containing parallel routes. Here, we review different single-molecule sensitive fluorescence methods that we employ routinely to investigate viruses. We provide a brief overview of the microscopy hardware needed and discuss the different methods and their application. In particular, we review how we applied (i) single-molecule Förster resonance energy transfer (smFRET) to probe the subviral human immunodeficiency virus (HIV-1) integrase (IN) quaternary structure; (ii) single particle tracking to study interactions of the simian virus 40 with membranes; (iii) 3D confocal microscopy and smFRET to quantify the HIV-1 pre-integration complex content and quaternary structure; (iv) image correlation spectroscopy to quantify the cytosolic HIV-1 Gag assembly, and finally; (v) super-resolution microscopy to characterize the interaction of HIV-1 with tetherin during assembly. We hope this review is an incentive for setting up and applying similar single-virus imaging studies in daily virology practice.
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Affiliation(s)
- Nagma Parveen
- Laboratory for Photochemistry and Spectroscopy, Molecular Imaging and Photonics Division, Chemistry Department, KU Leuven, B-3001 Leuven, Belgium.
| | - Doortje Borrenberghs
- Laboratory for Photochemistry and Spectroscopy, Molecular Imaging and Photonics Division, Chemistry Department, KU Leuven, B-3001 Leuven, Belgium.
| | - Susana Rocha
- Laboratory for Photochemistry and Spectroscopy, Molecular Imaging and Photonics Division, Chemistry Department, KU Leuven, B-3001 Leuven, Belgium.
| | - Jelle Hendrix
- Laboratory for Photochemistry and Spectroscopy, Molecular Imaging and Photonics Division, Chemistry Department, KU Leuven, B-3001 Leuven, Belgium.
- Dynamic Bioimaging Lab, Advanced Optical Microscopy Centre and Biomedical Research Institute (BIOMED), Hasselt University, B-3590 Diepenbeek, Belgium.
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Imaging, Tracking and Computational Analyses of Virus Entry and Egress with the Cytoskeleton. Viruses 2018; 10:v10040166. [PMID: 29614729 PMCID: PMC5923460 DOI: 10.3390/v10040166] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 03/27/2018] [Accepted: 03/28/2018] [Indexed: 12/27/2022] Open
Abstract
Viruses have a dual nature: particles are “passive substances” lacking chemical energy transformation, whereas infected cells are “active substances” turning-over energy. How passive viral substances convert to active substances, comprising viral replication and assembly compartments has been of intense interest to virologists, cell and molecular biologists and immunologists. Infection starts with virus entry into a susceptible cell and delivers the viral genome to the replication site. This is a multi-step process, and involves the cytoskeleton and associated motor proteins. Likewise, the egress of progeny virus particles from the replication site to the extracellular space is enhanced by the cytoskeleton and associated motor proteins. This overcomes the limitation of thermal diffusion, and transports virions and virion components, often in association with cellular organelles. This review explores how the analysis of viral trajectories informs about mechanisms of infection. We discuss the methodology enabling researchers to visualize single virions in cells by fluorescence imaging and tracking. Virus visualization and tracking are increasingly enhanced by computational analyses of virus trajectories as well as in silico modeling. Combined approaches reveal previously unrecognized features of virus-infected cells. Using select examples of complementary methodology, we highlight the role of actin filaments and microtubules, and their associated motors in virus infections. In-depth studies of single virion dynamics at high temporal and spatial resolutions thereby provide deep insight into virus infection processes, and are a basis for uncovering underlying mechanisms of how cells function.
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