1
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Xiang Z, He S, Chen R, Liu S, Liu M, Xu L, Zheng J, Jiang Z, Ma L, Sun Y, Qin Y, Chen Y, Li W, Wang X, Chen G, Lei W. Two-photon live imaging of direct glia-to-neuron conversion in the mouse cortex. Neural Regen Res 2024; 19:1781-1788. [PMID: 38103245 PMCID: PMC10960291 DOI: 10.4103/1673-5374.386401] [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: 04/28/2023] [Revised: 08/23/2023] [Accepted: 09/26/2023] [Indexed: 12/18/2023] Open
Abstract
JOURNAL/nrgr/04.03/01300535-202408000-00032/figure1/v/2023-12-16T180322Z/r/image-tiff Over the past decade, a growing number of studies have reported transcription factor-based in situ reprogramming that can directly convert endogenous glial cells into functional neurons as an alternative approach for neuroregeneration in the adult mammalian central nervous system. However, many questions remain regarding how a terminally differentiated glial cell can transform into a delicate neuron that forms part of the intricate brain circuitry. In addition, concerns have recently been raised around the absence of astrocyte-to-neuron conversion in astrocytic lineage-tracing mice. In this study, we employed repetitive two-photon imaging to continuously capture the in situ astrocyte-to-neuron conversion process following ectopic expression of the neural transcription factor NeuroD1 in both proliferating reactive astrocytes and lineage-traced astrocytes in the mouse cortex. Time-lapse imaging over several weeks revealed the step-by-step transition from a typical astrocyte with numerous short, tapered branches to a typical neuron with a few long neurites and dynamic growth cones that actively explored the local environment. In addition, these lineage-converting cells were able to migrate radially or tangentially to relocate to suitable positions. Furthermore, two-photon Ca2+ imaging and patch-clamp recordings confirmed that the newly generated neurons exhibited synchronous calcium signals, repetitive action potentials, and spontaneous synaptic responses, suggesting that they had made functional synaptic connections within local neural circuits. In conclusion, we directly visualized the step-by-step lineage conversion process from astrocytes to functional neurons in vivo and unambiguously demonstrated that adult mammalian brains are highly plastic with respect to their potential for neuroregeneration and neural circuit reconstruction.
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Affiliation(s)
- Zongqin Xiang
- Guangdong-Hong Kong-Macau Institute of CNS Regeneration (GHMICR), Jinan University, Guangzhou, Guangdong Province, China
- Department of Neurosurgery, The First Affiliated Hospital, Jinan University, Guangzhou, Guangdong Province, China
- Laboratory for Neuroimmunology in Health and Diseases, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, Guangdong Province, China
| | - Shu He
- Guangdong-Hong Kong-Macau Institute of CNS Regeneration (GHMICR), Jinan University, Guangzhou, Guangdong Province, China
| | - Rongjie Chen
- Guangdong-Hong Kong-Macau Institute of CNS Regeneration (GHMICR), Jinan University, Guangzhou, Guangdong Province, China
| | - Shanggong Liu
- Guangdong-Hong Kong-Macau Institute of CNS Regeneration (GHMICR), Jinan University, Guangzhou, Guangdong Province, China
| | - Minhui Liu
- VIB-KU Leuven Center for Brain & Disease Research, Leuven, Flemish Region, Belgium
| | - Liang Xu
- Guangdong-Hong Kong-Macau Institute of CNS Regeneration (GHMICR), Jinan University, Guangzhou, Guangdong Province, China
| | - Jiajun Zheng
- Department of Neurosurgery, The First Affiliated Hospital, Jinan University, Guangzhou, Guangdong Province, China
| | - Zhouquan Jiang
- Guangdong-Hong Kong-Macau Institute of CNS Regeneration (GHMICR), Jinan University, Guangzhou, Guangdong Province, China
| | - Long Ma
- Guangdong-Hong Kong-Macau Institute of CNS Regeneration (GHMICR), Jinan University, Guangzhou, Guangdong Province, China
| | - Ying Sun
- Guangdong-Hong Kong-Macau Institute of CNS Regeneration (GHMICR), Jinan University, Guangzhou, Guangdong Province, China
| | - Yongpeng Qin
- Guangdong-Hong Kong-Macau Institute of CNS Regeneration (GHMICR), Jinan University, Guangzhou, Guangdong Province, China
| | - Yi Chen
- Guangdong-Hong Kong-Macau Institute of CNS Regeneration (GHMICR), Jinan University, Guangzhou, Guangdong Province, China
| | - Wen Li
- Guangdong-Hong Kong-Macau Institute of CNS Regeneration (GHMICR), Jinan University, Guangzhou, Guangdong Province, China
| | - Xiangyu Wang
- Department of Neurosurgery, The First Affiliated Hospital, Jinan University, Guangzhou, Guangdong Province, China
| | - Gong Chen
- Guangdong-Hong Kong-Macau Institute of CNS Regeneration (GHMICR), Jinan University, Guangzhou, Guangdong Province, China
| | - Wenliang Lei
- Guangdong-Hong Kong-Macau Institute of CNS Regeneration (GHMICR), Jinan University, Guangzhou, Guangdong Province, China
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Blyton MDJ, Pyne M, Young P, Chappell K. Koala retrovirus load and non-A subtypes are associated with secondary disease among wild northern koalas. PLoS Pathog 2022; 18:e1010513. [PMID: 35588407 PMCID: PMC9119473 DOI: 10.1371/journal.ppat.1010513] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 04/08/2022] [Indexed: 01/17/2023] Open
Abstract
Koala Retrovirus (KoRV) has been associated with neoplasia in the vulnerable koala (Phascolarctos cinereus). However, there are conflicting findings regarding its association with secondary disease. We undertook a large-scale assessment of how the different KoRV subtypes and viral load are associated with Chlamydia pecorum infection and a range of disease pathologies in 151 wild koalas admitted for care to Currumbin Wildlife Hospital, Australia. Viral load (KoRV pol copies per ml of plasma) was the best predictor of more disease pathologies than any other KoRV variable. The predicted probability of a koala having disease symptoms increased from 25% to over 85% across the observed range of KoRV load, while the predicted probability of C. pecorum infection increased from 40% to over 80%. We found a negative correlation between the proportion of env deep sequencing reads that were endogenous KoRV-A and total KoRV load. This is consistent with suppression of endogenous KoRV-A, while the exogenous KoRV subtypes obtain high infection levels. Additionally, we reveal evidence that the exogenous subtypes are directly associated with secondary disease, with the proportion of reads that were the endogenous KoRV-A sequence a negative predictor of overall disease probability after the effect of KoRV load was accounted for. Further, koalas that were positive for KoRV-D or KoRV-D/F were more likely to have urogenital C. pecorum infection or low body condition score, respectively, irrespective of KoRV load. By contrast, our findings do not support previous findings that KoRV-B in particular is associated with Chlamydial disease. Based on these findings we suggest that koala research and conservation programs should target understanding what drives individual differences in KoRV load and limiting exogenous subtype diversity within populations, rather than seeking to eliminate any particular subtype.
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Affiliation(s)
- Michaela D. J. Blyton
- The University of Queensland, School of Chemistry and Molecular Biosciences, St Lucia, Queensland, Australia
- * E-mail: (MB); (KC)
| | - Michael Pyne
- Currumbin Wildlife Hospital and Foundation, Currumbin, Queensland, Australia
| | - Paul Young
- The University of Queensland, School of Chemistry and Molecular Biosciences, St Lucia, Queensland, Australia
| | - Keith Chappell
- The University of Queensland, School of Chemistry and Molecular Biosciences, St Lucia, Queensland, Australia
- The University of Queensland, Australian Institute of Bioengineering and Nanotechnology, St Lucia, Queensland, Australia
- * E-mail: (MB); (KC)
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3
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Selyutina A, Persaud M, Lee K, KewalRamani V, Diaz-Griffero F. Nuclear Import of the HIV-1 Core Precedes Reverse Transcription and Uncoating. Cell Rep 2021; 32:108201. [PMID: 32997983 PMCID: PMC7871456 DOI: 10.1016/j.celrep.2020.108201] [Citation(s) in RCA: 63] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 07/15/2020] [Accepted: 09/03/2020] [Indexed: 12/25/2022] Open
Abstract
HIV-1 reverse transcription (RT) occurs before or during uncoating, but the cellular compartment where RT and uncoating occurs is unknown. Using imaging and biochemical assays to track HIV-1 capsids in the nucleus during infection, we demonstrated that higher-order capsid complexes and/or complete cores containing the viral genome are imported into the nucleus. Inhibition of RT does not prevent capsid nuclear import; thus, RT may occur in nuclear compartments. Cytosolic and nuclear fractions of infected cells reveal that most RT intermediates are enriched in nuclear fractions, suggesting that HIV-1 RT occurs in the nucleus alongside uncoating. In agreement, we find that capsid in the nucleus induces recruitment of cleavage and polyadenylation specific factor 6 (CPSF6) to SC35 nuclear speckles, which are highly active transcription sites, suggesting that CPSF6 through capsid is recruiting viral complexes to SC35 speckles for the occurrence of RT. Thus, nuclear import precedes RT and uncoating, which fundamentally changes our understanding of HIV-1 infection. Selyutina et al. show that HIV-1 cores containing the viral genome are imported into the nucleus for reverse transcription and uncoating. HIV-1 cores in the nucleus are recruited by CPSF6 to SC35 highly active transcription domains for viral reverse transcription, integration, and/or expression.
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Affiliation(s)
| | - Mirjana Persaud
- Department of Microbiology and Immunology, Einstein, Bronx, NY 10461, USA
| | - Kyeongeun Lee
- Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702-1201, USA
| | - Vineet KewalRamani
- Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702-1201, USA
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The avian retroviral receptor Tva mediates the uptake of transcobalamin bound vitamin B12 (cobalamin). J Virol 2021; 95:JVI.02136-20. [PMID: 33504597 PMCID: PMC8103681 DOI: 10.1128/jvi.02136-20] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The Avian sarcoma and leukosis viruses (ASLVs) are important chicken pathogens. Some of the virus subgroups, including ASLV-A and K, utilize the Tva receptor for cell entrance. Though Tva was identified three decades ago, its physiological function remains unknown. Previously, we have noted an intriguing resemblance and orthology between the chicken gene coding for Tva and the human gene coding for CD320, a receptor involved in cellular uptake of transcobalamin (TC) in complex with vitamin B12/cobalamin (Cbl).Here we show that both the transmembrane and the glycosylphosphatidylinositol (GPI)-anchored form of Tva in the chicken cell line DF-1 promotes the uptake of Cbl with help of expressed and purified chicken TC. The uptake of TC-Cbl complex was monitored using an isotope- or fluorophore-labeled Cbl. We show that (i) TC-Cbl is internalized in chicken cells; and (ii) the uptake is lower in the Tva-knockout cells and higher in Tva-overexpressing cells when compared with wild type chicken cells. The relation between physiological function of Tva and its role in infection was elaborated by showing that infection with ASLV subgroups (targeting Tva) impairs the uptake of TC-Cbl, while this is not the case for cells infected with ASLV-B (not recognized by Tva). In addition, exposure of the cells to a high concentration of TC-Cbl alleviates the infection with Tva-dependent ASLV.IMPORTANCE: We demonstrate that the ASLV receptor Tva participates in the physiological uptake of TC-Cbl, because the viral infection suppresses the uptake of Cbl and vice versa. Our results pave the road for future studies addressing the issues: (i) whether a virus infection can be inhibited by TC-Cbl complexes in vivo; and (ii) whether any human virus employs the human TC-Cbl receptor CD320. In broader terms, our study sheds light on the intricate interplay between physiological roles of cellular receptors and their involvement in virus infection.
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Hernandez-Gonzalez M, Larocque G, Way M. Viral use and subversion of membrane organization and trafficking. J Cell Sci 2021; 134:jcs252676. [PMID: 33664154 PMCID: PMC7610647 DOI: 10.1242/jcs.252676] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Membrane trafficking is an essential cellular process conserved across all eukaryotes, which regulates the uptake or release of macromolecules from cells, the composition of cellular membranes and organelle biogenesis. It influences numerous aspects of cellular organisation, dynamics and homeostasis, including nutrition, signalling and cell architecture. Not surprisingly, malfunction of membrane trafficking is linked to many serious genetic, metabolic and neurological disorders. It is also often hijacked during viral infection, enabling viruses to accomplish many of the main stages of their replication cycle, including entry into and egress from cells. The appropriation of membrane trafficking by viruses has been studied since the birth of cell biology and has helped elucidate how this integral cellular process functions. In this Review, we discuss some of the different strategies viruses use to manipulate and take over the membrane compartments of their hosts to promote their replication, assembly and egress.
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Affiliation(s)
- Miguel Hernandez-Gonzalez
- Cellular Signalling and Cytoskeletal Function Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Gabrielle Larocque
- Cellular Signalling and Cytoskeletal Function Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Michael Way
- Cellular Signalling and Cytoskeletal Function Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
- Department of Infectious Disease, Imperial College, London W2 1PG, UK
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Singh SP, Raja S, Mahalingam S. Viral protein X unlocks the nuclear pore complex through a human Nup153-dependent pathway to promote nuclear translocation of the lentiviral genome. Mol Biol Cell 2020; 31:304-317. [PMID: 31913756 PMCID: PMC7183765 DOI: 10.1091/mbc.e19-08-0438] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Simian immunodeficiency virus (SIV) and human immunodeficiency virus 2 (HIV-2) display unique ability to infect nondividing target cells. Viral protein X (Vpx) of HIV-2/SIV is known to be involved in the nuclear import of viral genome in nondividing cells, but the mechanism remains poorly understood. In the present investigation for the first time we provide evidence that Vpx of SIVsmPBj1.9 physically interacts with human nucleoporin 153 (Nup153), which is known to provide a docking site for protein-cargo complexes at the nuclear pore complex (NPC). Results from superresolution-structured illumination microscopy studies reveal that Vpx interaction with NPC-associated Nup153 is critical for its efficient nuclear translocation. Virion-associated MAPK/ERK-2-mediated phosphorylation of Vpx plays a critical role in its interaction with human Nup153 and this interaction was found to be evolutionarily conserved in various SIV isolates and HIV-2. Interestingly, MAPK/ERK-2 packaging defective SIV failed to promote the efficient nuclear import of viral genome and suggests that MAPK/ERK-2-mediated Vpx phosphorylation is important for its interaction with Nup153, which is critical for lentiviruses to establish infection in nondividing target cells. Together, our data elucidate the mechanism by which Vpx orchestrates the challenging task of nuclear translocation of HIV-2/SIV genome in nondividing target cells.
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Affiliation(s)
- Satya Prakash Singh
- Laboratory of Molecular Cell Biology, Indian Institute of Technology-Madras, Chennai 600 036, India
| | - Sebastian Raja
- Laboratory of Molecular Cell Biology, Indian Institute of Technology-Madras, Chennai 600 036, India
| | - Sundarasamy Mahalingam
- Laboratory of Molecular Cell Biology, Indian Institute of Technology-Madras, Chennai 600 036, India.,National Cancer Tissue Biobank, Bhupat and Jyoti Mehta School of Biosciences, Department of Biotechnology, Indian Institute of Technology-Madras, Chennai 600 036, India
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7
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Im I, Son YS, Jung KB, Kang I, Teh BE, Lee KB, Son MY, Kim J. Mass cytometry-based single-cell analysis of human stem cell reprogramming uncovers differential regulation of specific pluripotency markers. J Biol Chem 2019; 294:18547-18556. [PMID: 31570522 DOI: 10.1074/jbc.ra119.009061] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 09/25/2019] [Indexed: 12/22/2022] Open
Abstract
Human induced pluripotent stem cells (hiPSCs) are reprogrammed from somatic cells and are regarded as promising sources for regenerative medicine and disease research. Recently, techniques for analyses of individual cells, such as single-cell RNA-Seq and mass cytometry, have been used to understand the stem cell reprogramming process in the mouse. However, the reprogramming process in hiPSCs remains poorly understood. Here we used mass cytometry to analyze the expression of pluripotency and cell cycle markers in the reprogramming of human stem cells. We confirmed that, during reprogramming, the main cell population was shifted to an intermediate population consisting of neither fibroblasts nor hiPSCs. Detailed population analyses using computational approaches, including dimensional reduction by spanning-tree progression analysis of density-normalized events, PhenoGraph, and diffusion mapping, revealed several distinct cell clusters representing the cells along the reprogramming route. Interestingly, correlation analysis of various markers in hiPSCs revealed that the pluripotency marker TRA-1-60 behaves in a pattern that is different from other pluripotency markers. Furthermore, we found that the expression pattern of another pluripotency marker, octamer-binding protein 4 (OCT4), was distinctive in the pHistone-H3high population (M phase) of the cell cycle. To the best of our knowledge, this is the first mass cytometry-based investigation of human reprogramming and pluripotency. Our analysis elucidates several aspects of hiPSC reprogramming, including several intermediate cell clusters active during the process of reprogramming and distinctive marker expression patterns in hiPSCs.
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Affiliation(s)
- Ilkyun Im
- Stem Cell Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahag-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Ye Seul Son
- Stem Cell Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahag-ro, Yuseong-gu, Daejeon 34141, Republic of Korea; Department of Functional Genomics, Korea Research Institute of Bioscience and Biotechnology School of Bioscience, Korea University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea
| | - Kwang Bo Jung
- Stem Cell Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahag-ro, Yuseong-gu, Daejeon 34141, Republic of Korea; Department of Functional Genomics, Korea Research Institute of Bioscience and Biotechnology School of Bioscience, Korea University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea
| | - Insoo Kang
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520; Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06520; Department of Orthopedics and Rehabilitation, Yale University School of Medicine, New Haven, Connecticut 06520
| | - Boon-Eng Teh
- Fluidigm Corporation, South San Francisco, California 94080-7603
| | - Kyung-Bok Lee
- Center for Research Equipment, Korea Basic Science Institute, 162 Yeongudanji-ro, Ochang-eup, Cheongwon-gu, Cheongju 28119, Republic of Korea
| | - Mi-Young Son
- Stem Cell Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahag-ro, Yuseong-gu, Daejeon 34141, Republic of Korea; Department of Functional Genomics, Korea Research Institute of Bioscience and Biotechnology School of Bioscience, Korea University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea.
| | - Janghwan Kim
- Stem Cell Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahag-ro, Yuseong-gu, Daejeon 34141, Republic of Korea; Department of Functional Genomics, Korea Research Institute of Bioscience and Biotechnology School of Bioscience, Korea University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea.
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Albagli O, Maugein A, Huijbregts L, Bredel D, Carlier G, Martin P, Scharfmann R. New α- and SIN γ-retrovectors for safe transduction and specific transgene expression in pancreatic β cell lines. BMC Biotechnol 2019; 19:35. [PMID: 31208395 PMCID: PMC6580483 DOI: 10.1186/s12896-019-0531-9] [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: 12/06/2018] [Accepted: 06/06/2019] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Viral vectors are invaluable tools to transfer genes and/or regulatory sequences into differentiated cells such as pancreatic cells. To date, several kinds of viral vectors have been used to transduce different pancreatic cell types, including insulin-producing β cells. However, few studies have used vectors derived from « simple » retroviruses, such as avian α- or mouse γ-retroviruses, despite their high experimental convenience. Moreover, such vectors were never designed to specifically target transgene expression into β cells. RESULTS We here describe two novel α- or SIN (Self-Inactivating) γ-retrovectors containing the RIP (Rat Insulin Promoter) as internal promoter. These two retrovectors are easily produced in standard BSL2 conditions, rapidly concentrated if needed, and harbor a large multiple cloning site. For the SIN γ-retrovector, either the VSV-G (pantropic) or the retroviral ecotropic (rodent specific) envelope was used. For the α-retrovector, we used the A type envelope, as its receptor, termed TVA, is only naturally present in avian cells and can efficiently be provided to mammalian β cells through either exogenous expression upon cDNA transfer or gesicle-mediated delivery of the protein. As expected, the transgenes cloned into the two RIP-containing retrovectors displayed a strong preferential expression in β over non-β cells compared to transgenes cloned in their non-RIP (CMV- or LTR-) regulated counterparts. We further show that RIP activity of both retrovectors mirrored fluctuations affecting endogenous INSULIN gene expression in human β cells. Finally, both α- and SIN γ-retrovectors were extremely poorly mobilized by the BXV1 xenotropic retrovirus, a common invader of human cells grown in immunodeficient mice, and, most notably, of human β cell lines. CONCLUSION Our novel α- and SIN γ-retrovectors are safe and convenient tools to stably and specifically express transgene(s) in mammalian β cells. Moreover, they both reproduce some regulatory patterns affecting INSULIN gene expression. Thus, they provide a helpful tool to both study the genetic control of β cell function and monitor changes in their differentiation status.
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Affiliation(s)
- Olivier Albagli
- INSERM U1016, CNRS UMR8104, Institut Cochin, Université Paris Descartes, 123 Boulevard de Port-Royal, 75014, Paris, France.
| | - Alicia Maugein
- INSERM U1016, CNRS UMR8104, Institut Cochin, Université Paris Descartes, 123 Boulevard de Port-Royal, 75014, Paris, France
| | - Lukas Huijbregts
- INSERM U1016, CNRS UMR8104, Institut Cochin, Université Paris Descartes, 123 Boulevard de Port-Royal, 75014, Paris, France
| | - Delphine Bredel
- INSERM U1016, CNRS UMR8104, Institut Cochin, Université Paris Descartes, 123 Boulevard de Port-Royal, 75014, Paris, France.,Present Address: Laboratoire de Recherche Translationnelle en Immunothérapie, Institut Gustave Roussy, 114 Rue Edouard Vaillant, 94800, Villejuif, France
| | - Géraldine Carlier
- INSERM U1016, CNRS UMR8104, Institut Cochin, Université Paris Descartes, 123 Boulevard de Port-Royal, 75014, Paris, France
| | - Patrick Martin
- Université Côte d'Azur, CNRS UMR7277 INSERM U1099, iBV (Institut de Biologie Valrose), Université Nice Sophia Antipolis, Bâtiment Sciences Naturelles; UFR Sciences, Parc Valrose, 28, avenue Valrose, 06108, Nice Cedex 2, France
| | - Raphaël Scharfmann
- INSERM U1016, CNRS UMR8104, Institut Cochin, Université Paris Descartes, 123 Boulevard de Port-Royal, 75014, Paris, France
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9
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Ding J, Lin ZQ, Jiang JM, Seidman CE, Seidman JG, Pu WT, Wang DZ. Preparation of rAAV9 to Overexpress or Knockdown Genes in Mouse Hearts. J Vis Exp 2016. [PMID: 28060283 DOI: 10.3791/54787] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Controlling the expression or activity of specific genes through the myocardial delivery of genetic materials in murine models permits the investigation of gene functions. Their therapeutic potential in the heart can also be determined. There are limited approaches for in vivo molecular intervention in the mouse heart. Recombinant adeno-associated virus (rAAV)-based genome engineering has been utilized as an essential tool for in vivo cardiac gene manipulation. The specific advantages of this technology include high efficiency, high specificity, low genomic integration rate, minimal immunogenicity, and minimal pathogenicity. Here, a detailed procedure to construct, package, and purify the rAAV9 vectors is described. Subcutaneous injection of rAAV9 into neonatal pups results in robust expression or efficient knockdown of the gene(s) of interest in the mouse heart, but not in the liver and other tissues. Using the cardiac-specific TnnT2 promoter, high expression of GFP gene in the heart was obtained. Additionally, target mRNA was inhibited in the heart when a rAAV9-U6-shRNA was utilized. Working knowledge of rAAV9 technology may be useful for cardiovascular investigations.
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Affiliation(s)
- Jian Ding
- Department of Cardiology, Boston Children's Hospital; Department of Pediatrics, Harvard Medical School;
| | - Zhi-Qiang Lin
- Department of Cardiology, Boston Children's Hospital; Department of Pediatrics, Harvard Medical School
| | - Jian-Ming Jiang
- Department of Genetics, Harvard Medical School; Howard Hughes Medical Institute
| | - Christine E Seidman
- Department of Genetics, Harvard Medical School; Howard Hughes Medical Institute
| | - Jonathan G Seidman
- Department of Genetics, Harvard Medical School; Howard Hughes Medical Institute
| | - William T Pu
- Department of Cardiology, Boston Children's Hospital; Department of Pediatrics, Harvard Medical School
| | - Da-Zhi Wang
- Department of Cardiology, Boston Children's Hospital; Department of Pediatrics, Harvard Medical School;
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10
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Exploring viral infection using single-cell sequencing. Virus Res 2016; 239:55-68. [PMID: 27816430 DOI: 10.1016/j.virusres.2016.10.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 10/21/2016] [Accepted: 10/24/2016] [Indexed: 12/31/2022]
Abstract
Single-cell sequencing (SCS) has emerged as a valuable tool to study cellular heterogeneity in diverse fields, including virology. By studying the viral and cellular genome and/or transcriptome, the dynamics of viral infection can be investigated at single cell level. Most studies have explored the impact of cell-to-cell variation on the viral life cycle from the point of view of the virus, by analyzing viral sequences, and from the point of view of the cell, mainly by analyzing the cellular host transcriptome. In this review, we will focus on recent studies that use single-cell sequencing to explore viral diversity and cell variability in response to viral replication.
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Abstract
Retroviruses and LTR retrotransposons are transposable elements that encapsidate the RNAs that are intermediates in the transposition of DNA copies of their genomes (proviruses), from one cell (or one locus) to another. Mechanistic similarities in DNA transposase enzymes and retroviral/retrotransposon integrases underscore the close evolutionary relationship among these elements. The retroviruses are very ancient infectious agents, presumed to have evolved from Ty3/Gypsy LTR retrotransposons (1), and DNA copies of their sequences can be found embedded in the genomes of most, if not all, members of the tree of life. All retroviruses share a specific gene arrangement and similar replication strategies. However, given their ancestries and occupation of diverse evolutionary niches, it should not be surprising that unique sequences have been acquired in some retroviral genomes and that the details of the mechanism by which their transposition is accomplished can vary. While every step in the retrovirus lifecycle is, in some sense, relevant to transposition, this Chapter focuses mainly on the early phase of retroviral replication, during which viral DNA is synthesized and integrated into its host genome. Some of the initial studies that set the stage for current understanding are highlighted, as well as more recent findings obtained through use of an ever-expanding technological toolbox including genomics, proteomics, and siRNA screening. Persistence in the area of structural biology has provided new insight into conserved mechanisms as well as variations in detail among retroviruses, which can also be instructive.
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Affiliation(s)
- Anna Marie Skalka
- Fox Chase Cancer Center 333 Cottman Avenue Philadelphia, PA 19111 United States 2157282192 2157282778 (fax)
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12
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Le Sage V, Mouland AJ, Valiente-Echeverría F. Roles of HIV-1 capsid in viral replication and immune evasion. Virus Res 2014; 193:116-29. [PMID: 25036886 DOI: 10.1016/j.virusres.2014.07.010] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 07/04/2014] [Accepted: 07/07/2014] [Indexed: 02/07/2023]
Abstract
The primary roles of the human immunodeficiency virus type 1 (HIV-1) capsid (CA) protein are to encapsidate and protect the viral RNA genome. It is becoming increasing apparent that HIV-1 CA is a multifunctional protein that acts early during infection to coordinate uncoating, reverse transcription, nuclear import of the pre-integration complex and integration of double stranded viral DNA into the host genome. Additionally, numerous recent studies indicate that CA is playing a crucial function in HIV-1 immune evasion. Here we summarize the current knowledge on HIV-1 CA and its interactions with the host cell to promote infection. The fact that CA engages in a number of different protein-protein interactions with the host makes it an interesting target for the development of new potent antiviral agents.
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Affiliation(s)
- Valerie Le Sage
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute, Jewish General Hospital, Montréal, Québec H3T1E2, Canada; Department of Medicine, Division of Experimental Medicine, McGill University, Montréal, Québec H3A 1A3, Canada
| | - Andrew J Mouland
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute, Jewish General Hospital, Montréal, Québec H3T1E2, Canada; Department of Medicine, Division of Experimental Medicine, McGill University, Montréal, Québec H3A 1A3, Canada; Department of Microbiology and Immunology, McGill University, Montréal, Québec, H3A2B4, Canada
| | - Fernando Valiente-Echeverría
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute, Jewish General Hospital, Montréal, Québec H3T1E2, Canada; Department of Medicine, Division of Experimental Medicine, McGill University, Montréal, Québec H3A 1A3, Canada.
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13
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Hossain A, Ali K, Shin CG. Nuclear localization signals in prototype foamy viral integrase for successive infection and replication in dividing cells. Mol Cells 2014; 37:140-8. [PMID: 24598999 PMCID: PMC3935627 DOI: 10.14348/molcells.2014.2331] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 12/11/2013] [Accepted: 12/13/2013] [Indexed: 11/27/2022] Open
Abstract
We identified four basic amino acid residues as nuclear localization signals (NLS) in the C-terminal domain of the prototype foamy viral (PFV) integrase (IN) protein that were essential for viral replication. We constructed seven point mutants in the C-terminal domain by changing the lysine and arginine at residues 305, 308, 313, 315, 318, 324, and 329 to threonine or proline, respectively, to identify residues conferring NLS activity. Our results showed that mutation of these residues had no effect on expression assembly, release of viral particles, or in vitro recombinant IN enzymatic activity. However, mutations at residues 305 (R → T), 313(R → T), 315(R → P), and 329(R → T) lead to the production of defective viral particles with loss of infectivity, whereas non-defective mutations at residues 308(R → T), 318(K → T), and 324(K → T) did not show any adverse effects on subsequent production or release of viral particles. Sub-cellular fractionation and immunostaining for viral protein PFV-IN and PFV-Gag localization revealed predominant cytoplasmic localization of PFV-IN in defective mutants, whereas cytoplasmic and nuclear localization of PFV-IN was observed in wild type and non-defective mutants. However sub-cellular localization of PFV-Gag resulted in predominant nuclear localization and less presence in the cytoplasm of the wild type and non-defective mutants. But defective mutants showed only nuclear localization of Gag. Therefore, we postulate that four basic arginine residues at 305, 313, 315 and 329 confer the karyoplilic properties of PFV-IN and are essential for successful viral integration and replication.
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Affiliation(s)
- Alamgir Hossain
- Department of Biotechnology, Chung-Ang University, Ansung 456-756,
Korea
| | - Khadem Ali
- Department of Biotechnology, Chung-Ang University, Ansung 456-756,
Korea
| | - Cha-Gyun Shin
- Department of Biotechnology, Chung-Ang University, Ansung 456-756,
Korea
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14
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Henning MS, Dubose BN, Burse MJ, Aiken C, Yamashita M. In vivo functions of CPSF6 for HIV-1 as revealed by HIV-1 capsid evolution in HLA-B27-positive subjects. PLoS Pathog 2014; 10:e1003868. [PMID: 24415937 PMCID: PMC3887095 DOI: 10.1371/journal.ppat.1003868] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 11/22/2013] [Indexed: 11/21/2022] Open
Abstract
The host protein CPSF6 possesses a domain that can interact with the HIV-1 capsid (CA) protein. CPSF6 has been implicated in regulating HIV-1 nuclear entry. However, its functional significance for HIV-1 replication has yet to be firmly established. Here we provide evidence for two divergent functions of CPSF6 for HIV-1 replication in vivo. We demonstrate that endogenous CPSF6 exerts an inhibitory effect on naturally occurring HIV-1 variants in individuals carrying the HLA-B27 allele. Conversely, we find a strong selective pressure in these individuals to preserve CPSF6 binding, while escaping from the restrictive activity by CPSF6. This active maintenance of CPSF6 binding during HIV-1 CA evolution in vivo contrasts with the in vitro viral evolution, which can reduce CPSF6 binding to evade from CPSF6-mediated restriction. Thus, these observations argue for a beneficial role of CPSF6 for HIV-1 in vivo. CPSF6-mediated restriction renders HIV-1 less dependent or independent from TNPO3, RanBP2 and Nup153, host factors implicated in HIV-1 nuclear entry. However, viral evolution that maintains CPSF6 binding in HLA-B27+ subjects invariably restores the ability to utilize these host factors, which may be the major selective pressure for CPSF6 binding in vivo. Our study uncovers two opposing CA-dependent functions of CPSF6 in HIV-1 replication in vivo; however, the benefit for binding CPSF6 appears to outweigh the cost, providing support for a vital function of CPSF6 during HIV-1 replication in vivo. The viral capsid (CA) protein of HIV-1 determines both the ability to infect non-dividing cells and the utilization of host factors implicated in nuclear entry. Understanding how CA controls these two properties is critical. CPSF6, a CA-interacting host protein, may be important for these properties but its precise role remains unclear. Here we provide direct evidence for the involvement of endogenous CPSF6 during HIV-1 infection. We found that CPSF6 blocks CA mutants that are impaired for infection of non-dividing cells. This CPSF6-mediated inhibition also targets early escape variants that arise in HIV-1 infected HLA-B27+ patients. Moreover, this CPSF6-mediated inhibition, together with robust CTL response, appears to be critical for viral suppression, because viruses derived after late viral breakthrough in these individuals were no longer sensitive to the antiviral activity of CPSF6. However, we also report indirect evidence for a potentially beneficial role for CPSF6 in HIV-1 replication, because escape from this inhibition in vivo was paradoxically accompanied by a strict preservation of the CPSF6 binding pocket. These results highlight the unique characteristics of the HIV-CPSF6 interactions in which CPSF6 can be either beneficial or detrimental for viral replication in a CA-specific manner.
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Affiliation(s)
- Matthew S. Henning
- Aaron Diamond AIDS Research Center, New York, New York, United States of America
| | - Brittany N. Dubose
- Aaron Diamond AIDS Research Center, New York, New York, United States of America
| | - Mallori J. Burse
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Christopher Aiken
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Masahiro Yamashita
- Aaron Diamond AIDS Research Center, New York, New York, United States of America
- * E-mail:
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15
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Avian retroviral replication. Curr Opin Virol 2013; 3:664-9. [PMID: 24011707 DOI: 10.1016/j.coviro.2013.08.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 08/14/2013] [Accepted: 08/15/2013] [Indexed: 12/17/2022]
Abstract
Avian retroviruses were originally identified as cancer-inducting filterable agents in chicken neoplasms at the beginning of the 20th century. Since their discovery, the study of these simple retroviruses has contributed greatly to our understanding of viral replication and cancer. Avian retroviruses continue to evolve and have great economic importance in the poultry industry worldwide. The aim of this review is to provide a broad overview of the genome, pathology, and replication of avian retroviruses. Notable gaps in our current knowledge are highlighted, and areas where avian retroviruses differ from other retroviruses are emphasized.
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Influenza A virus NS1 induces G0/G1 cell cycle arrest by inhibiting the expression and activity of RhoA protein. J Virol 2013; 87:3039-52. [PMID: 23283961 DOI: 10.1128/jvi.03176-12] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Influenza A virus is an important pathogenic virus known to induce host cell cycle arrest in G(0)/G(1) phase and create beneficial conditions for viral replication. However, how the virus achieves arrest remains unclear. We investigated the mechanisms underlying this process and found that the nonstructural protein 1 (NS1) is required. Based on this finding, we generated a viable influenza A virus (H1N1) lacking the entire NS1 gene to study the function of this protein in cell cycle regulation. In addition to some cell cycle regulators that were changed, the concentration and activity of RhoA protein, which is thought to be pivotal for G(1)/S phase transition, were also decreased with overexpressing NS1. And in the meantime, the phosphorylation level of cell cycle regulator pRb, downstream of RhoA kinase, was decreased in an NS1-dependent manner. These findings indicate that the NS1 protein induces G(0)/G(1) cell cycle arrest mainly through interfering with the RhoA/pRb signaling cascade, thus providing favorable conditions for viral protein accumulation and replication. We further investigated the NS1 protein of avian influenza virus (H5N1) and found that it can also decrease the expression and activity of RhoA, suggesting that the H5N1 virus may affect the cell cycle through the same mechanism. The NS1/RhoA/pRb cascade, which can induce the G(0)/G(1) cell cycle arrest identified here, provides a unified explanation for the seemingly different NS1 functions involved in viral replication events. Our findings shed light on the mechanism of influenza virus replication and open new avenues for understanding the interaction between pathogens and hosts.
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17
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Suerth JD, Schambach A, Baum C. Genetic modification of lymphocytes by retrovirus-based vectors. Curr Opin Immunol 2012; 24:598-608. [PMID: 22995202 DOI: 10.1016/j.coi.2012.08.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 08/23/2012] [Indexed: 01/02/2023]
Abstract
The genetic modification of lymphocytes is an important topic in the emerging field of gene therapy. Many clinical trials targeting immunodeficiency syndromes or cancer have shown therapeutic benefit; further applications address inflammatory and infectious disorders. Retroviral vector development requires a detailed understanding of the interactions with the host. Most researchers have used simple gammaretroviral vectors to modify lymphocytes, either directly or via hematopoietic stem and progenitor cells. Lentiviral, spumaviral (foamyviral) and alpharetroviral vectors were designed to reduce the necessity for cell stimulation and to utilize potentially safer integration properties. Novel surface modifications (pseudotyping) and transgenes, built using synthetic components, expand the retroviral toolbox, altogether promising increased specificity and potency. Product consistency will be an important criterion for routine clinical use.
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Affiliation(s)
- Julia D Suerth
- Institute of Experimental Hematology, Hannover Medical School, Carl-Neuberg-Straße 1, D-30625 Hannover, Germany
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18
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The Role of TNPO3 in HIV-1 Replication. Mol Biol Int 2012; 2012:868597. [PMID: 22888429 PMCID: PMC3409535 DOI: 10.1155/2012/868597] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Revised: 06/04/2012] [Accepted: 06/05/2012] [Indexed: 12/12/2022] Open
Abstract
TNPO3, transportin-SR2 or Tnp3, a member of the karyopherin β superfamily of proteins, is important for the ability of human immunodeficiency virus (HIV-1) to achieve productive infection, as TNPO3 depletion in human cells leads to a dramatic reduction of infection. Here we describe and discuss recent findings suggesting that TNPO3 assists HIV-1 replication in the nucleus and in fact that TNPO3 may assist PIC maturation in the nucleus. In addition, the viral determinant for the requirement of TNPO3 in HIV-1 infection is discussed. This paper summarizes the most significant recent discoveries about this important host factor and its role in HIV-1 replication.
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19
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LEDGF (p75) promotes DNA-end resection and homologous recombination. Nat Struct Mol Biol 2012; 19:803-10. [DOI: 10.1038/nsmb.2314] [Citation(s) in RCA: 149] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Accepted: 05/24/2012] [Indexed: 12/11/2022]
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20
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Andrade AA, Brasil BSAF, Pereira ACTC, Ferreira PCP, Kroon EG, Bonjardim CA. Vaccinia virus regulates expression of p21WAF1/Cip1 in A431 cells. Mem Inst Oswaldo Cruz 2010; 105:269-77. [DOI: 10.1590/s0074-02762010000300005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Accepted: 04/01/2010] [Indexed: 11/22/2022] Open
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21
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The foamy virus genome remains unintegrated in the nuclei of G1/S phase-arrested cells, and integrase is critical for preintegration complex transport into the nucleus. J Virol 2009; 84:2832-42. [PMID: 20032182 DOI: 10.1128/jvi.02435-09] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Foamy viruses are a member of the spumavirus subfamily of retroviruses with unique mechanisms of virus replication. Foamy virus replication is cell cycle dependent; however, the genome is found in the nuclei of cells arrested in the G(1)/S phase. Despite the presence of genome in the nuclei of growth-arrested cells, there is no viral gene expression, thus explaining its dependency on cell cycle. This report shows that the foamy virus genome remains unintegrated in G(1)/S phase-arrested cells. The foamy virus genome is detected by confocal microscopy in the nuclei of both dividing and growth-arrested cells. Alu PCR revealed foamy virus-specific DNA amplification from genomic DNA isolated in cycling cells at 24 h postinfection. In arrested cells no foamy virus DNA band was detected in cells harvested at 1 or 7 days after infection, and a very faint band that is significantly less than DNA amplified from cycling cells was observed at day 15. After these cells were arrested at the G(1)/S phase for 1, 7, or 15 days they were allowed to cycle, at which time foamy virus-specific DNA amplification was readily observed. Taken together, these results suggest that the foamy virus genome persists in nondividing cells without integrating. We have also established evidence for the first time that the foamy virus genome and Gag translocation into the nucleus are dependent on integrase in cycling cells, implicating the role of integrase in transport of the preintegration complex into the nucleus. Furthermore, despite the presence of a nuclear localization signal sequence in Gag, we observed no foamy virus Gag importation into the nucleus in the absence of integrase.
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22
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Shimozono S, Tsutsui H, Miyawaki A. Diffusion of large molecules into assembling nuclei revealed using an optical highlighting technique. Biophys J 2009; 97:1288-94. [PMID: 19720016 DOI: 10.1016/j.bpj.2009.06.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2008] [Revised: 05/25/2009] [Accepted: 06/05/2009] [Indexed: 01/16/2023] Open
Abstract
The nuclear envelope (NE) defines the nuclear compartment, and nuclear pore complexes (NPCs) on the NE form aqueous passages through which small water-soluble molecules can passively diffuse. It is well known that proteins smaller than 50 kDa can diffuse though NPCs, whereas proteins larger than 60 kDa rarely enter by passive diffusion. Little, however, is known about how this size cutoff develops as the NE reassembles and the nucleus expands. In 1987, a well-known study identified an efficient mechanism by which large diffusing proteins (> 60 kDa) were excluded from the reassembling nucleus after mitosis. Since then, it has been generally accepted that after mitosis, newly formed nuclei completely exclude all proteins except those that are initially bound to the mitotic chromosomes and those that are selectively imported through NPCs. Here, the tetrameric complex of the photoconvertible fluorescent protein KikGR ( approximately 103 kDa) was optically highlighted in the cytoplasm and followed to examine its entry into nuclei. Remarkably, highlighted complexes efficiently entered newly assembled nuclei during an approximately 20-min period after the completion of cytokinesis. Because KikGR contains no known nuclear-localization or chromosome-binding sequences, our results indicate the diffusion barrier is less restrictive during nuclear reassembly.
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Affiliation(s)
- Satoshi Shimozono
- Laboratory for Cell Function Dynamics, Advanced Technology Development Group, Brain Science Institute, Institute of Physical and Chemical Research, Saitama, Japan
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23
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Cellular restriction targeting viral capsids perturbs human immunodeficiency virus type 1 infection of nondividing cells. J Virol 2009; 83:9835-43. [PMID: 19625401 DOI: 10.1128/jvi.01084-09] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The ability of human immunodeficiency virus (HIV) to infect nondividing cells is a fundamental property by which HIV replicates in critical target cells, such as macrophages and resting CD4(+) T cells. Recent studies have revealed that the capsid (CA) protein is a dominant factor that determines retrovirus infectivity in nondividing cells, and several mutations in HIV type 1 (HIV-1) CA abrogate the ability of HIV-1 to infect nondividing cells. We present evidence for a connection between cellular restriction against viral capsids and the resistance of nondividing cells to retrovirus infection. TRIM proteins that are able to target incoming viral capsids restrict HIV-1 more potently in nondividing cells than in dividing cells, thus rendering HIV-1 infection dependent on cell division. Moreover, cyclophilin A, another cellular protein that binds to HIV-1 CA, regulates HIV-1 infection of nondividing cells. Together, these data demonstrate the importance of capsid-binding cellular proteins in the control of the cell cycle independence of HIV-1. We propose that cellular restrictions to retroviral infections are themselves cell cycle dependent.
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25
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Integrase interacts with nucleoporin NUP153 to mediate the nuclear import of human immunodeficiency virus type 1. J Virol 2009; 83:6522-33. [PMID: 19369352 DOI: 10.1128/jvi.02061-08] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The ability to traverse an intact nuclear envelope and productively infect nondividing cells is a salient feature of human immunodeficiency virus type 1 (HIV-1) and other lentiviruses, but the viral factors and mechanism of nuclear entry have not been defined. HIV-1 integrase (IN) is implicated to play a role in the nuclear import of the virus, but the cellular pathway for IN trafficking and the role of IN in mediating the nuclear import of viral particles are unknown. Using a semipermeabilized cell assay, we observed that the nuclear import of IN was not the result of passive diffusion but occurred independently of cytosolic factors, metabolic energy, and the classical receptor-mediated, Ran-dependent import pathways. To determine if IN enters the nucleus by interacting with the nucleopore complex (NPC), we found that IN bound directly with the FxFG-rich C-terminal domain of nucleoporin 153 (NUP153C). When added in excess to the import assay, NUP153C inhibited the nuclear import of IN. Known binding partners of NUP153C competed with IN for binding with NUP153 and also inhibited the nuclear import of IN. In cultured cells, overexpression of NUP153C reduced the infectivity of an HIV-derived vector by interfering with the nuclear translocation of the viral cDNA. These results support a functional role for the IN-NUP153 interaction in HIV-1 replication and suggest that HIV-1 subviral particles gain access to the nucleus by interacting directly with the NPC via the binding of particle-associated IN to NUP153C.
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Abstract
HIV infection leads to progressive CD4 T cell depletion, resulting in the development of AIDS. The mechanisms that trigger T cell death after HIV infection are still not fully understood, but a lot of data indicate that apoptosis of uninfected CD4 lymphocytes plays a major role. HIV directly modulates cell death using various strategies in which several viral proteins, in particular the envelope glycoproteins (Env), play an essential role. Importantly, Env, expressed on infected cells, triggers autophagy in uninfected CD4 T cells, leading to their apoptosis. Furthermore, HIV, like other viruses, has evolved strategies to inhibit this autophagic process in HIV-infected cells. This discovery further increases the level of complexity of the cellular processes involved in HIV-induced pathology. Interestingly, HIV protease inhibitors, currently used in highly active antiretroviral therapy (HAART), are able to induce autophagy in cancer cells, leading to a recent repositioning of these drugs as anticancer agents. This review presents an overview of the relationship between HIV, HAART, and autophagy.
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Affiliation(s)
- Lucile Espert
- University of Montpellier, Institut de Biologie, 4, Bd Henri IV, CS 69033, 34965, Montpellier Cedex 2, France
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Andrake MD, Sauter MM, Boland K, Goldstein AD, Hussein M, Skalka AM. Nuclear import of Avian Sarcoma Virus integrase is facilitated by host cell factors. Retrovirology 2008; 5:73. [PMID: 18687138 PMCID: PMC2527327 DOI: 10.1186/1742-4690-5-73] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Accepted: 08/07/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Integration of retroviral DNA into the host cell genome is an obligatory step in the virus life cycle. In previous reports we identified a sequence (amino acids 201-236) in the linker region between the catalytic core and C-terminal domains of the avian sarcoma virus (ASV) integrase protein that functions as a transferable nuclear localization signal (NLS) in mammalian cells. The sequence is distinct from all known NLSs but, like many, contains basic residues that are essential for activity. RESULTS Our present studies with digitonin-permeabilized HeLa cells show that nuclear import mediated by the NLS of ASV integrase is an active, saturable, and ATP-dependent process. As expected for transport through nuclear pore complexes, import is blocked by treatment of cells with wheat germ agglutinin. We also show that import of ASV integrase requires soluble cellular factors but does not depend on binding the classical adapter Importin-alpha. Results from competition studies indicate that ASV integrase relies on one or more of the soluble components that mediate transport of the linker histone H1. CONCLUSION These results are consistent with a role for ASV integrase and cytoplasmic cellular factors in the nuclear import of its viral DNA substrate, and lay the foundation for identification of host cell components that mediate this reaction.
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Affiliation(s)
- Mark D Andrake
- Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, PA 19111, USA.
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28
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Evidence for direct involvement of the capsid protein in HIV infection of nondividing cells. PLoS Pathog 2008; 3:1502-10. [PMID: 17967060 PMCID: PMC2042020 DOI: 10.1371/journal.ppat.0030156] [Citation(s) in RCA: 161] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Accepted: 09/13/2007] [Indexed: 12/19/2022] Open
Abstract
HIV and other lentiviruses can productively infect nondividing cells, whereas most other retroviruses, such as murine leukemia virus, require cell division for efficient infection. However, the determinants for this phenotype have been controversial. Here, we show that HIV-1 capsid (CA) is involved in facilitating HIV infection of nondividing cells because amino acid changes on CA severely disrupt the cell-cycle independence of HIV. One mutant in the N-terminal domain of CA in particular has lost the cell-cycle independence in all cells tested, including primary macrophages. The defect in this mutant appears to be at a stage past nuclear entry. We also find that the loss of cell-cycle independence can be cell-type specific, which suggests that a cellular factor affects the ability of HIV to infect nondividing cells. Our data suggest that CA is directly involved at some step in the viral life cycle that is important for infection of nondividing cells. HIV and related viruses are unusual among retroviruses in their ability to replicate independently of cell-cycle progression of target cells. However, the determinants of this phenotype have been controversial. Here, we identified mutations on the surface of the capsid (CA) protein that reduce the ability of HIV to infect nondividing cells. These mutations also confer cell-cycle dependency on HIV, even in dividing cells. Interestingly, some CA mutants lose cell-cycle independence only in certain cell types. Thus, these findings suggest that a cellular factor targeting CA regulates HIV-1 infection in nondividing cells. Surprisingly, these mutations do not appear to affect nuclear localization of viral genomes, which points to a novel regulation of the cell-cycle independence of HIV by the CA protein.
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Zamborlini A, Lehmann-Che J, Clave E, Giron ML, Tobaly-Tapiero J, Roingeard P, Emiliani S, Toubert A, de Thé H, Saïb A. Centrosomal pre-integration latency of HIV-1 in quiescent cells. Retrovirology 2007; 4:63. [PMID: 17845727 PMCID: PMC2014762 DOI: 10.1186/1742-4690-4-63] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Accepted: 09/10/2007] [Indexed: 11/25/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) efficiently replicates in dividing and non-dividing cells. However, HIV-1 infection is blocked at an early post-entry step in quiescent CD4+ T cells in vitro. The molecular basis of this restriction is still poorly understood. Here, we show that in quiescent cells, incoming HIV-1 sub-viral complexes concentrate and stably reside at the centrosome for several weeks. Upon cell activation, viral replication resumes leading to viral gene expression. Thus, HIV-1 can persist in quiescent cells as a stable, centrosome-associated, pre-integration intermediate.
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Affiliation(s)
| | | | - Emmanuel Clave
- INSERM U662, Laboratoire d'Immunologie et d'Histocompatibilité AP-HP, Paris, France
| | - Marie-Lou Giron
- CNRS UMR7151, Université Paris 7, Hôpital Saint-Louis, Paris, France
| | | | | | | | - Antoine Toubert
- INSERM U662, Laboratoire d'Immunologie et d'Histocompatibilité AP-HP, Paris, France
| | - Hugues de Thé
- CNRS UMR7151, Université Paris 7, Hôpital Saint-Louis, Paris, France
| | - Ali Saïb
- CNRS UMR7151, Université Paris 7, Hôpital Saint-Louis, Paris, France
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30
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Lehmann-Che J, Renault N, Giron ML, Roingeard P, Clave E, Tobaly-Tapiero J, Bittoun P, Toubert A, de Thé H, Saïb A. Centrosomal latency of incoming foamy viruses in resting cells. PLoS Pathog 2007; 3:e74. [PMID: 17530924 PMCID: PMC1871606 DOI: 10.1371/journal.ppat.0030074] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2006] [Accepted: 04/06/2007] [Indexed: 12/18/2022] Open
Abstract
Completion of early stages of retrovirus infection depends on the cell cycle. While gammaretroviruses require mitosis for proviral integration, lentiviruses are able to replicate in post-mitotic non-dividing cells. Resting cells such as naive resting T lymphocytes from peripheral blood cannot be productively infected by retroviruses, including lentiviruses, but the molecular basis of this restriction remains poorly understood. We demonstrate that in G0 resting cells (primary fibroblasts or peripheral T cells), incoming foamy retroviruses accumulate in close proximity to the centrosome, where they lie as structured and assembled capsids for several weeks. Under these settings, virus uncoating is impaired, but upon cell stimulation, Gag proteolysis and capsid disassembly occur, which allows viral infection to proceed. The data imply that foamy virus uncoating is the rate-limiting step for productive infection of primary G0 cells. Incoming foamy retroviruses can stably persist at the centrosome, awaiting cell stimulation to initiate capsid cleavage, nuclear import, and viral gene expression. Naive quiescent CD4-positive T cells or monocytes that are in the G0 stage of the cell cycle cannot be productively infected by retroviruses in vitro, but the molecular basis of this restriction remains poorly understood. In this report, we demonstrate that incoming foamy retroviruses remain around the centrosome as structured and assembled capsids for weeks in resting cultures. Under these conditions, virus uncoating is impaired, but upon cell activation, viral capsids undergo proteolysis and disassembly, allowing infection to proceed. Maintenance of incoming viral capsids at the centrosome in resting cells could be a strategy that viruses have evolved to rapidly respond to stimuli received by the cell. The cellular signal triggering the uncoating process upon cell stimulation remains unclear, but is likely linked to the centrosome cycle.
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Affiliation(s)
| | - Noémie Renault
- Université Paris 7, Paris, France
- CNRS, UMR 7151, Paris, France
| | - Marie Lou Giron
- Université Paris 7, Paris, France
- CNRS, UMR 7151, Paris, France
| | - Philippe Roingeard
- Université François Rabelais and Centre Hospitalier Régional Universitaire de Tours, Tours, France
- INSERM ERI 19, Tours, France
| | - Emmanuel Clave
- Laboratoire d'Immunologie et d'Histocompatibilité, Assistance Publique–Hôpitaux de Paris, Paris, France
- INSERM, U662, Paris, France
| | | | | | - Antoine Toubert
- Laboratoire d'Immunologie et d'Histocompatibilité, Assistance Publique–Hôpitaux de Paris, Paris, France
- INSERM, U662, Paris, France
| | - Hugues de Thé
- Université Paris 7, Paris, France
- CNRS, UMR 7151, Paris, France
| | - Ali Saïb
- Université Paris 7, Paris, France
- CNRS, UMR 7151, Paris, France
- * To whom correspondence should be addressed. E-mail:
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31
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Li FQ, Tam JP, Liu DX. Cell cycle arrest and apoptosis induced by the coronavirus infectious bronchitis virus in the absence of p53. Virology 2007; 365:435-45. [PMID: 17493653 PMCID: PMC7103336 DOI: 10.1016/j.virol.2007.04.015] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2007] [Revised: 03/04/2007] [Accepted: 04/05/2007] [Indexed: 01/01/2023]
Abstract
Manipulation of the cell cycle and induction of apoptosis are two common strategies used by many viruses to regulate their infection cycles. In cells infected with coronaviruses, cell cycle perturbation and apoptosis were observed in several reports. However, little is known about how these effects are brought out, and how manipulation of the functions of host cells would influence the replication cycle of coronavirus. In this study, we demonstrate that infection with coronavirus infectious bronchitis virus (IBV) imposed a growth-inhibitory effect on cultured cells by inducing cell cycle arrest at S and G2/M phases in both p53-null cell line H1299 and Vero cells. This cell cycle arrest was catalyzed by the modulation of various cell cycle regulatory genes and the accumulation of hypophosphorylated RB, but was independent of p53. Proteasome inhibitors, such as lactacystin and NLVS, could bypass the IBV-induced S-phase arrest by restoring the expression of corresponding cyclin/Cdk complexes. Our data also showed that cell cycle arrest at both S- and G2/M-phases was manipulated by IBV for the enhancement of viral replication. In addition, apoptosis induced by IBV at late stages of the infection cycle in cultured cells was shown to be p53-independent. This conclusion was drawn based on the observations that apoptosis occurred in both IBV-infected H1299 and Vero cells, and that IBV infection did not affect the expression of p53 in host cells.
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Affiliation(s)
- Frank Q Li
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
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32
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Abstract
Human immunodeficiency virus 1 (HIV-1) and other retroviruses synthesize a DNA copy of their genome after entry into the host cell. Integration of this DNA into the host cell's genome is an essential step in the viral replication cycle. The viral DNA is synthesized in the cytoplasm and is associated with viral and cellular proteins in a large nucleoprotein complex. Before integration into the host genome can occur, this complex must be transported to the nucleus and must cross the nuclear envelope. This Review summarizes our current knowledge of how this journey is accomplished.
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Affiliation(s)
- Youichi Suzuki
- Laboratory for Host Factors, Center for Emerging Virus Research, Institute for Virus Research, Kyoto University, 53 Shogoin-Kawara-cho, Sakyo-ku, Kyoto 606-8507, Japan
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33
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Renault N, Saïb A. From cell surface to the nucleus, a short but critical journey for retroviruses. Future Virol 2006. [DOI: 10.2217/17460794.1.3.331] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
From the cell surface to the nucleus, retroviruses will face multiple obstacles, crossing physical barriers such as the plasma membrane, but also finding their pathway through a viscous cytoplasm. At the same time, retroviruses have to overcome cellular defenses, interfering with the early steps of the virus life cycle. Although the general outcomes of this journey have been known for several decades, the stepwise interactions taking place between cellular and viral factors, which will transform the incoming viral RNA genome into a double-stranded DNA competent for integration, remain largely unknown. In this sense, the uncoating process and the molecular basis of intracellular trafficking of preintegration complexes are still poorly defined. Additionally, other key stages, which have been the focus of many reports, still require some clarification, as is the case for the precise implication of viral and cellular determinants involved in nuclear import of preintegration complexes.
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Affiliation(s)
- Noémie Renault
- CNRS UMR7151, Université Paris 7, Hôpital Saint-Louis, Centre Hayem, 1 Avenue Claude Vellefaux, 75475 Paris Cedex 10, France
| | - Ali Saïb
- CNRS UMR7151, Université Paris 7, Hôpital Saint-Louis, Centre Hayem, 1 Avenue Claude Vellefaux, 75475 Paris Cedex 10, France
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34
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Yamashita M, Emerman M. Retroviral infection of non-dividing cells: old and new perspectives. Virology 2006; 344:88-93. [PMID: 16364740 DOI: 10.1016/j.virol.2005.09.012] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2005] [Accepted: 09/10/2005] [Indexed: 12/16/2022]
Abstract
The dependence of retroviral replication on cell proliferation was described as early as 1958, although different classes of retroviruses are able to infect non-dividing cells with different efficiencies. For example, the human immunodeficiency virus (HIV) and other lentiviruses infect most non-dividing cells nearly as well as dividing cells, while the gammaretroviruses such as the murine leukemia virus (MLV) cannot infect non-dividing cells, and other retroviruses have intermediate phenotypes. One exception to the ability of HIV to infect non-dividing cells involves resting CD4+ T cells in vitro where there are multiple restrictions. However, recent data show that there is massive infection of non-activated CD4+ T cell during acute infection which suggests that the situation is different in vivo. Finally, much work trying to explain the difference between HIV and MLV in non-dividing cells has focused on describing the ability of HIV to enter the nucleus during interphase. However, we suggest that events in the viral life-cycle other than nuclear import may be more important in determining the ability of a given retrovirus to infect non-dividing cells.
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Affiliation(s)
- Masahiro Yamashita
- Division of Human Biology, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N, Seattle, WA 98109-1024, USA
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35
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Wang E, Albritton L, Ross SR. Identification of the segments of the mouse transferrin receptor 1 required for mouse mammary tumor virus infection. J Biol Chem 2006; 281:10243-9. [PMID: 16481319 DOI: 10.1074/jbc.m511572200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Most enveloped viruses enter cells through binding of virion surface envelope proteins to receptors found on the plasma membrane of the cell. The beta retrovirus mouse mammary tumor virus (MMTV) uses transferrin receptor 1 (TfR1) to enter cells in a pH-dependent mechanism, probably co-trafficking with TfR1 to an acidic compartment where virus entry occurs. We have shown here that, although mouse and rat TfR1 function as entry receptors, cat, dog, hamster, or human TfR1s do not support MMTV infection. We also demonstrated that MMTV entry is independent of transferrin, iron, and the TfR1 cofactor hereditary hematochromatosis HFE protein. Using chimeric mouse/human hybrid TfR1 constructs, we determined the site of interaction with MMTV and found that it maps to two segments physically disparate from the TfR and HFE binding sites. Thus, MMTV has apparently evolved to enter cells independently of the iron status of the host.
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Affiliation(s)
- Enxiu Wang
- Department of Microbiology and Abramson Family Cancer Center, University of Pennsylvania, Rm. 313 BRB II/III, 421 Curie Boulevard, Philadelphia, PA 19104, USA
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36
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Abstract
Retroviruses are efficient vehicles for delivering transgenes in vivo. Their ability to integrate into the host genome, providing a permanent imprint of their genes in the host, is a key asset for gene therapy. Furthermore, the lentivirus subset of retroviruses can infect nondividing as well as dividing cells. This expands the cell types capable of gene therapy, driving the development of lentiviral vectors. However, the precise mechanisms used by different retroviruses to efficiently deliver their genes into cell nuclei remains largely unclear. Understanding these molecular mechanisms may reveal features to improve the efficacy of current retroviral vectors. Moreover, this knowledge may expose elements pliable to other gene therapy vehicles to improve their in vivo performance and circumvent the biosafety concerns of using retroviral vectors. Therefore, the mechanisms underlying the early trafficking of retroviral vectors in host cells are reviewed here, as understood from studying the native retroviruses. Events after virus entry up to nuclear delivery of the viral cDNA are discussed. Cellular obstacles faced by these retroviral vectors and how they advance beyond these barriers is emphasized.
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Affiliation(s)
- J L Anderson
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611-3093, USA
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37
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Yamashita M, Emerman M. The cell cycle independence of HIV infections is not determined by known karyophilic viral elements. PLoS Pathog 2005; 1:e18. [PMID: 16292356 PMCID: PMC1283251 DOI: 10.1371/journal.ppat.0010018] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2005] [Accepted: 09/19/2005] [Indexed: 01/01/2023] Open
Abstract
Human immunodeficiency virus and other lentiviruses infect cells independent of cell cycle progression, but gammaretroviruses, such as the murine leukemia virus (MLV) require passage of cells through mitosis. This property is thought to be important for the ability of HIV to infect resting CD4+ T cells and terminally differentiated macrophages. Multiple and independent redundant nuclear localization signals encoded by HIV have been hypothesized to facilitate migration of viral genomes into the nucleus. The integrase (IN) protein of HIV is one of the HIV elements that targets to the nucleus; however, its role in nuclear entry of virus genomes has been difficult to describe because mutations in IN are pleiotropic. To investigate the importance of the HIV IN protein for infection of non-dividing cells, and to investigate whether or not IN was redundant with other viral signals for cell cycle-independent nuclear entry, we constructed an HIV-based chimeric virus in which the entire IN protein of HIV was replaced by that of MLV. This chimeric virus with a heterologous IN was infectious at a low level, and was able to integrate in an IN-dependent manner. Furthermore, this virus infected non-dividing cells as well as it infected dividing cells. Moreover, we used the chimeric HIV with MLV IN to further eliminate all of the other described nuclear localization signals from an HIV genome—matrix, IN, Viral Protein R, and the central polypurine tract—and show that no combination of the virally encoded NLS is essential for the ability of HIV to infect non-dividing cells. Human immunodeficiency virus can infect many cells irrespective of whether or not they are dividing, whereas some other retroviruses, such as the murine leukemia virus can only infect cells that are proliferating. This property is important for the ability of HIV to establish infections in critical cell types in infected people. Multiple and redundant signals encoded by HIV have been hypothesized to facilitate migration of viral genomes into the nucleus. However, here the authors eliminated all four described nuclear localizing signals from an HIV genome and show that no combination of these virally encoded signals is essential for the ability of HIV to infect non-dividing cells. They suggest that another step of the virus lifecycle, other than nuclear import, is the rate-limiting step that determines the cell cycle dependence/independence of retroviral infections.
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Affiliation(s)
- Masahiro Yamashita
- Division of Human Biology and Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Michael Emerman
- Division of Human Biology and Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- * To whom correspondence should be addressed. E-mail:
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