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Tsurutani N, Momose F, Ogawa K, Sano K, Morikawa Y. Intracellular trafficking of HIV-1 Gag via Syntaxin 6-positive compartments/vesicles: Involvement in tumor necrosis factor secretion. J Biol Chem 2024; 300:105687. [PMID: 38280430 PMCID: PMC10891346 DOI: 10.1016/j.jbc.2024.105687] [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] [Received: 11/06/2023] [Revised: 01/03/2024] [Accepted: 01/04/2024] [Indexed: 01/29/2024] Open
Abstract
HIV-1 Gag protein is synthesized in the cytosol and is transported to the plasma membrane, where viral particle assembly and budding occur. Endosomes are alternative sites of Gag accumulation. However, the intracellular transport pathways and carriers for Gag have not been clarified. We show here that Syntaxin6 (Syx6), a soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) involved in membrane fusion in post-Golgi networks, is a molecule responsible for Gag trafficking and also for tumor necrosis factor-α (TNFα) secretion and that Gag and TNFα are cotransported via Syx6-positive compartments/vesicles. Confocal and live-cell imaging revealed that Gag colocalized and cotrafficked with Syx6, a fraction of which localizes in early and recycling endosomes. Syx6 knockdown reduced HIV-1 particle production, with Gag distributed diffusely throughout the cytoplasm. Coimmunoprecipitation and pulldown show that Gag binds to Syx6, but not its SNARE partners or their assembly complexes, suggesting that Gag preferentially binds free Syx6. The Gag matrix domain and the Syx6 SNARE domain are responsible for the interaction and cotrafficking. In immune cells, Syx6 knockdown/knockout similarly impaired HIV-1 production. Interestingly, HIV-1 infection facilitated TNFα secretion, and this enhancement did not occur in Syx6-depleted cells. Confocal and live-cell imaging revealed that TNFα and Gag partially colocalized and were cotransported via Syx6-positive compartments/vesicles. Biochemical analyses indicate that TNFα directly binds the C-terminal domain of Syx6. Altogether, our data provide evidence that both Gag and TNFα make use of Syx6-mediated trafficking machinery and suggest that Gag expression does not inhibit but rather facilitates TNFα secretion in HIV-1 infection.
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Affiliation(s)
- Naomi Tsurutani
- Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan
| | - Fumitaka Momose
- Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan
| | - Keiji Ogawa
- Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan
| | - Kouichi Sano
- Osaka Medical and Pharmaceutical University, Takatsuki, Osaka, Japan
| | - Yuko Morikawa
- Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan.
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2
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Qin X, Jiang N, Zhu J, Zhang YA, Tu J. Snakehead vesiculovirus hijacks SH3RF1 for replication via mediating K63-linked ubiquitination at K264 of the phosphoprotein. Int J Biol Macromol 2024; 255:128201. [PMID: 37979762 DOI: 10.1016/j.ijbiomac.2023.128201] [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] [Received: 07/31/2023] [Revised: 11/13/2023] [Accepted: 11/15/2023] [Indexed: 11/20/2023]
Abstract
Snakehead vesiculovirus (SHVV) is a type of rhabdovirus that causes serious economic losses in snakehead fish culture in China. However, no specific antiviral drugs or vaccines are currently available for SHVV infection. In this study, 4D label-free ubiquitome analysis of SHVV-infected cells revealed dozens of ubiquitinated sites on the five SHVV proteins. We focused on investigating the ubiquitination of phosphoprotein (P), a viral polymerase co-factor involved in viral replication. SHVV-P was proved to be ubiquitinated via K63-linked ubiquitination at lysine 264 (K264). Overexpression of wild-type P, but not its K264R mutant, facilitated SHVV replication, indicating that K264 ubiquitination of the P protein is critical for SHVV replication. RNAi screening of 26 cellular E3 ubiquitin ligases identified five pro-viral factors for SHVV replication, including macrophage erythroblast attacher (MAEA), TNF receptor-associated factor 7 (TRAF7), and SH3 domain-containing ring finger protein 1 (SH3RF1), which interacted with and mediated ubiquitination of SHVV P. TRAF7 and SH3RF1, but not MAEA, mediated K63-linked ubiquitination of SHVV P, while only SH3RF1 mediated K264 ubiquitination of SHVV P. Besides, overexpression of SH3RF1 promoted SHVV replication and maintained the stability of SHVV P. In summary, SH3RF1 mediated K63-linked ubiquitination of SHVV P at K264 to facilitate SHVV replication, providing targets for developing anti-SHVV drugs and live-attenuated SHVV vaccines. Our study provides novel insights into the role of P protein in the replication of single-stranded, negative-sense RNA viruses.
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Affiliation(s)
- Xiangmou Qin
- State Key Laboratory of Agricultural Microbiology, Hubei Hongshan Laboratory, Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Ningyan Jiang
- State Key Laboratory of Agricultural Microbiology, Hubei Hongshan Laboratory, Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Jingjing Zhu
- State Key Laboratory of Agricultural Microbiology, Hubei Hongshan Laboratory, Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Yong-An Zhang
- State Key Laboratory of Agricultural Microbiology, Hubei Hongshan Laboratory, Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education, College of Fisheries, Huazhong Agricultural University, Wuhan, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
| | - Jiagang Tu
- State Key Laboratory of Agricultural Microbiology, Hubei Hongshan Laboratory, Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education, College of Fisheries, Huazhong Agricultural University, Wuhan, China.
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3
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Simpson LM, Glennie L, Brewer A, Zhao JF, Crooks J, Shpiro N, Sapkota GP. Target protein localization and its impact on PROTAC-mediated degradation. Cell Chem Biol 2022; 29:1482-1504.e7. [PMID: 36075213 DOI: 10.1016/j.chembiol.2022.08.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 06/24/2022] [Accepted: 08/15/2022] [Indexed: 12/21/2022]
Abstract
Proteolysis-targeting chimeras (PROTACs) bring a protein of interest (POI) into spatial proximity of an E3 ubiquitin ligase, promoting POI ubiquitylation and proteasomal degradation. PROTACs rely on endogenous cellular machinery to mediate POI degradation, therefore the subcellular location of the POI and access to the E3 ligase being recruited potentially impacts PROTAC efficacy. To interrogate whether the subcellular context of the POI influences PROTAC-mediated degradation, we expressed either Halo or FKBP12F36V (dTAG) constructs consisting of varying localization signals and tested the efficacy of their degradation by von Hippel-Lindau (VHL)- or cereblon (CRBN)-recruiting PROTACs targeting either Halo or dTAG. POIs were localized to the nucleus, cytoplasm, outer mitochondrial membrane, endoplasmic reticulum, Golgi, peroxisome or lysosome. Differentially localized Halo or FKBP12F36V proteins displayed varying levels of degradation using the same respective PROTACs, suggesting therefore that the subcellular context of the POI can influence the efficacy of PROTAC-mediated POI degradation.
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Affiliation(s)
- Luke M Simpson
- Medical Research Council (MRC) Protein Phosphorylation & Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Lorraine Glennie
- Medical Research Council (MRC) Protein Phosphorylation & Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Abigail Brewer
- Medical Research Council (MRC) Protein Phosphorylation & Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Jin-Feng Zhao
- Medical Research Council (MRC) Protein Phosphorylation & Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Jennifer Crooks
- Medical Research Council (MRC) Protein Phosphorylation & Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Natalia Shpiro
- Medical Research Council (MRC) Protein Phosphorylation & Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Gopal P Sapkota
- Medical Research Council (MRC) Protein Phosphorylation & Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
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4
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Jin X, Zhou R, Huang Y. Role of inflammasomes in HIV-1 infection and treatment. Trends Mol Med 2022; 28:421-434. [PMID: 35341684 DOI: 10.1016/j.molmed.2022.02.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 02/27/2022] [Accepted: 02/28/2022] [Indexed: 02/07/2023]
Abstract
Although combined antiretroviral therapy (cART) is effective in inhibiting human immunodeficiency virus type 1 (HIV-1) replication, it does not eradicate the virus because small amounts of latent HIV-1 provirus persist in quiescent memory CD4+ T cells. Therefore, strategies for eradicating latent HIV-1 are urgently needed. Recently, several studies have reported that the inflammatory response and lymphocyte death induced by HIV-1 depend on inflammasomes and pyroptosis, suggesting that inflammasomes and pyroptosis have a vital role in HIV-1 infection and contribute to the eradication of latent HIV-1. In this review, we summarize current knowledge of the role of inflammasomes, including NLR family pyrin domain-containing protein 3 (NLRP3), caspase recruitment domain-containing protein 8 (CARD8), interferon-inducible protein 16 (IFI16), NLRP1, NLR family CARD domain-containing 4 (NLRC4), and absent in melanoma 2 (AIM2), in HIV-1 infection and discuss promising therapeutic strategies for HIV-1-associated diseases by targeting inflammasomes.
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Affiliation(s)
- Xiangyu Jin
- Wuxi School of Medicine, Jiangnan University, Jiangsu, China
| | - Rongbin Zhou
- Hefei National Laboratory for Physical Sciences at Microscale, the CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Basic Medical Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China.
| | - Yi Huang
- Wuxi School of Medicine, Jiangnan University, Jiangsu, China.
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5
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Kjærner‐Semb E, Edvardsen RB, Ayllon F, Vogelsang P, Furmanek T, Rubin CJ, Veselov AE, Nilsen TO, McCormick SD, Primmer CR, Wargelius A. Comparison of anadromous and landlocked Atlantic salmon genomes reveals signatures of parallel and relaxed selection across the Northern Hemisphere. Evol Appl 2021; 14:446-461. [PMID: 33664787 PMCID: PMC7896726 DOI: 10.1111/eva.13129] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 08/17/2020] [Accepted: 08/18/2020] [Indexed: 12/21/2022] Open
Abstract
Most Atlantic salmon (Salmo salar L.) populations follow an anadromous life cycle, spending early life in freshwater, migrating to the sea for feeding, and returning to rivers to spawn. At the end of the last ice age ~10,000 years ago, several populations of Atlantic salmon became landlocked. Comparing their genomes to their anadromous counterparts can help identify genetic variation related to either freshwater residency or anadromy. The objective of this study was to identify consistently divergent loci between anadromous and landlocked Atlantic salmon strains throughout their geographical distribution, with the long-term aim of identifying traits relevant for salmon aquaculture, including fresh and seawater growth, omega-3 metabolism, smoltification, and disease resistance. We used a Pool-seq approach (n = 10-40 individuals per population) to sequence the genomes of twelve anadromous and six landlocked Atlantic salmon populations covering a large part of the Northern Hemisphere and conducted a genomewide association study to identify genomic regions having been under different selection pressure in landlocked and anadromous strains. A total of 28 genomic regions were identified and included cadm1 on Chr 13 and ppargc1a on Chr 18. Seven of the regions additionally displayed consistently reduced heterozygosity in fish obtained from landlocked populations, including the genes gpr132, cdca4, and sertad2 on Chr 15. We also found 16 regions, including igf1 on Chr 17, which consistently display reduced heterozygosity in the anadromous populations compared to the freshwater populations, indicating relaxed selection on traits associated with anadromy in landlocked salmon. In conclusion, we have identified 37 regions which may harbor genetic variation relevant for improving fish welfare and quality in the salmon farming industry and for understanding life-history traits in fish.
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Affiliation(s)
| | | | | | | | | | | | - Alexey E. Veselov
- Institute of Biology of the Karelian Research CentrePetrozavodskRussia
| | - Tom Ole Nilsen
- Department of Biological SciencesUniversity of BergenBergenNorway
| | - Stephen D. McCormick
- Conte Anadromous Fish Research LaboratoryU.S. Geological Survey, Leetown Science CenterTurners FallsMAUSA
| | - Craig R. Primmer
- Organismal and Evolutionary Biology Research ProgramFaculty of Biological and Environmental SciencesUniversity of HelsinkiHelsinkiFinland
- Institute of BiotechnologyUniversity of HelsinkiHelsinkiFinland
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6
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SH3RF3 promotes breast cancer stem-like properties via JNK activation and PTX3 upregulation. Nat Commun 2020; 11:2487. [PMID: 32427938 PMCID: PMC7237486 DOI: 10.1038/s41467-020-16051-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 04/08/2020] [Indexed: 02/08/2023] Open
Abstract
Cancer stem-like cells (CSCs) are the tumorigenic cell subpopulation and contribute to cancer recurrence and metastasis. However, the understanding of CSC regulatory mechanisms remains incomplete. By transcriptomic analysis, we identify a scaffold protein SH3RF3 (also named POSH2) that is upregulated in CSCs of breast cancer clinical tumors and cancer cell lines, and enhances the CSC properties of breast cancer cells. Mechanically, SH3RF3 interacts with the c-Jun N-terminal kinase (JNK) in a JNK-interacting protein (JIP)-dependent manner, leading to enhanced phosphorylation of JNK and activation of the JNK-JUN pathway. Further the JNK-JUN signaling expands CSC subpopulation by transcriptionally activating the expression of Pentraxin 3 (PTX3). The functional role of SH3RF3 in CSCs is validated with patient-derived organoid culture, and supported by clinical cohort analyses. In conclusion, our work elucidates the role and molecular mechanism of SH3RF3 in CSCs of breast cancer, and might provide opportunities for CSC-targeting therapy.
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7
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Colomer-Lluch M, Castro-Gonzalez S, Serra-Moreno R. Ubiquitination and SUMOylation in HIV Infection: Friends and Foes. Curr Issues Mol Biol 2019; 35:159-194. [PMID: 31422939 DOI: 10.21775/cimb.035.159] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
As intracellular parasites, viruses hijack the cellular machinery to facilitate their replication and spread. This includes favouring the expression of their viral genes over host genes, appropriation of cellular molecules, and manipulation of signalling pathways, including the post-translational machinery. HIV, the causative agent of AIDS, is notorious for using post-translational modifications to generate infectious particles. Here, we discuss the mechanisms by which HIV usurps the ubiquitin and SUMO pathways to modify both viral and host factors to achieve a productive infection, and also how the host innate sensing system uses these post-translational modifications to hinder HIV replication.
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Affiliation(s)
- Marta Colomer-Lluch
- IrsiCaixa AIDS Research Institute, Hospital Germans Trias i Pujol, Badalona, Spain
| | - Sergio Castro-Gonzalez
- Department of Biological Sciences, College of Arts and Sciences, Texas Tech University, Lubbock, TX, USA
| | - Ruth Serra-Moreno
- Department of Biological Sciences, College of Arts and Sciences, Texas Tech University, Lubbock, TX, USA
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8
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Sakai R, Fukuda R, Unida S, Aki M, Ono Y, Endo A, Kusumi S, Koga D, Fukushima T, Komada M, Okiyoneda T. The integral function of the endocytic recycling compartment is regulated by RFFL-mediated ubiquitylation of Rab11 effectors. J Cell Sci 2019; 132:jcs.228007. [PMID: 30659120 DOI: 10.1242/jcs.228007] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 01/03/2019] [Indexed: 12/11/2022] Open
Abstract
Endocytic trafficking is regulated by ubiquitylation (also known as ubiquitination) of cargoes and endocytic machineries. The role of ubiquitylation in lysosomal delivery has been well documented, but its role in the recycling pathway is largely unknown. Here, we report that the ubiquitin (Ub) ligase RFFL regulates ubiquitylation of endocytic recycling regulators. An RFFL dominant-negative (DN) mutant induced clustering of endocytic recycling compartments (ERCs) and delayed endocytic cargo recycling without affecting lysosomal traffic. A BioID RFFL interactome analysis revealed that RFFL interacts with the Rab11 effectors EHD1, MICALL1 and class I Rab11-FIPs. The RFFL DN mutant strongly captured these Rab11 effectors and inhibited their ubiquitylation. The prolonged interaction of RFFL with Rab11 effectors was sufficient to induce the clustered ERC phenotype and to delay cargo recycling. RFFL directly ubiquitylates these Rab11 effectors in vitro, but RFFL knockout (KO) only reduced the ubiquitylation of Rab11-FIP1. RFFL KO had a minimal effect on the ubiquitylation of EHD1, MICALL1, and Rab11-FIP2, and failed to delay transferrin recycling. These results suggest that multiple Ub ligases including RFFL regulate the ubiquitylation of Rab11 effectors, determining the integral function of the ERC.
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Affiliation(s)
- Ryohei Sakai
- Department of Biomedical Chemistry, School of Science and Technology, Kwansei Gakuin University, Hyogo 669-1337, Japan
| | - Ryosuke Fukuda
- Department of Biomedical Chemistry, School of Science and Technology, Kwansei Gakuin University, Hyogo 669-1337, Japan
| | - Shin Unida
- Department of Biomedical Chemistry, School of Science and Technology, Kwansei Gakuin University, Hyogo 669-1337, Japan
| | - Misaki Aki
- Department of Biomedical Chemistry, School of Science and Technology, Kwansei Gakuin University, Hyogo 669-1337, Japan
| | - Yuji Ono
- Department of Biomedical Chemistry, School of Science and Technology, Kwansei Gakuin University, Hyogo 669-1337, Japan
| | - Akinori Endo
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Satoshi Kusumi
- Division of Morphological Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan
| | - Daisuke Koga
- Department of Microscopic Anatomy and Cell Biology, Asahikawa Medical University, Asahikawa 078-8510, Hokkaido, Japan
| | - Toshiaki Fukushima
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Masayuki Komada
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Tsukasa Okiyoneda
- Department of Biomedical Chemistry, School of Science and Technology, Kwansei Gakuin University, Hyogo 669-1337, Japan
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9
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Lata S, Mishra R, Banerjea AC. Proteasomal Degradation Machinery: Favorite Target of HIV-1 Proteins. Front Microbiol 2018; 9:2738. [PMID: 30524389 PMCID: PMC6262318 DOI: 10.3389/fmicb.2018.02738] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2018] [Accepted: 10/26/2018] [Indexed: 12/17/2022] Open
Abstract
Proteasomal degradation pathways play a central role in regulating a variety of protein functions by controlling not only their turnover but also the physiological behavior of the cell. This makes it an attractive target for the pathogens, especially viruses which rely on the host cellular machinery for their propagation and pathogenesis. Viruses have evolutionarily developed various strategies to manipulate the host proteasomal machinery thereby creating a cellular environment favorable for their own survival and replication. Human immunodeficiency virus-1 (HIV-1) is one of the most dreadful viruses which has rapidly spread throughout the world and caused high mortality due to its high evolution rate. Here, we review the various mechanisms adopted by HIV-1 to exploit the cellular proteasomal machinery in order to escape the host restriction factors and components of host immune system for supporting its own multiplication, and successfully created an infection.
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Affiliation(s)
- Sneh Lata
- Virology Lab II, National Institute of Immunology, New Delhi, India
| | - Ritu Mishra
- Virology Lab II, National Institute of Immunology, New Delhi, India
| | - Akhil C Banerjea
- Virology Lab II, National Institute of Immunology, New Delhi, India
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10
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Chen L, Keppler OT, Schölz C. Post-translational Modification-Based Regulation of HIV Replication. Front Microbiol 2018; 9:2131. [PMID: 30254620 PMCID: PMC6141784 DOI: 10.3389/fmicb.2018.02131] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 08/20/2018] [Indexed: 12/13/2022] Open
Abstract
Human immunodeficiency virus (HIV) relies heavily on the host cellular machinery for production of viral progeny. To exploit cellular proteins for replication and to overcome host factors with antiviral activity, HIV has evolved a set of regulatory and accessory proteins to shape an optimized environment for its replication and to facilitate evasion from the immune system. Several cellular pathways are hijacked by the virus to modulate critical steps during the viral life cycle. Thereby, post-translational modifications (PTMs) of viral and cellular proteins gain increasingly attention as modifying enzymes regulate virtually every step of the viral replication cycle. This review summarizes the current knowledge of HIV-host interactions influenced by PTMs with a special focus on acetylation, ubiquitination, and phosphorylation of proteins linked to cellular signaling and viral replication. Insights into these interactions are surmised to aid development of new intervention strategies.
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Affiliation(s)
- Lin Chen
- Max von Pettenkofer-Institute and Gene Center, Virology, National Reference Center for Retroviruses, Faculty of Medicine, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Oliver T Keppler
- Max von Pettenkofer-Institute and Gene Center, Virology, National Reference Center for Retroviruses, Faculty of Medicine, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Christian Schölz
- Max von Pettenkofer-Institute and Gene Center, Virology, National Reference Center for Retroviruses, Faculty of Medicine, Ludwig-Maximilians-University Munich, Munich, Germany
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11
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Setz C, Friedrich M, Rauch P, Fraedrich K, Matthaei A, Traxdorf M, Schubert U. Inhibitors of Deubiquitinating Enzymes Block HIV-1 Replication and Augment the Presentation of Gag-Derived MHC-I Epitopes. Viruses 2017; 9:v9080222. [PMID: 28805676 PMCID: PMC5580479 DOI: 10.3390/v9080222] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 08/04/2017] [Accepted: 08/08/2017] [Indexed: 12/18/2022] Open
Abstract
In recent years it has been well established that two major constituent parts of the ubiquitin proteasome system (UPS)—the proteasome holoenzymes and a number of ubiquitin ligases—play a crucial role, not only in virus replication but also in the regulation of the immunogenicity of human immunodeficiency virus type 1 (HIV-1). However, the role in HIV-1 replication of the third major component, the deubiquitinating enzymes (DUBs), has remained largely unknown. In this study, we show that the DUB-inhibitors (DIs) P22077 and PR-619, specific for the DUBs USP7 and USP47, impair Gag processing and thereby reduce the infectivity of released virions without affecting viral protease activity. Furthermore, the replication capacity of X4- and R5-tropic HIV-1NL4-3 in human lymphatic tissue is decreased upon treatment with these inhibitors without affecting cell viability. Most strikingly, combinatory treatment with DIs and proteasome inhibitors synergistically blocks virus replication at concentrations where mono-treatment was ineffective, indicating that DIs can boost the therapeutic effect of proteasome inhibitors. In addition, P22077 and PR-619 increase the polyubiquitination of Gag and thus its entry into the UPS and the major histocompatibility complex (MHC)-I pathway. In summary, our data point towards a model in which specific inhibitors of DUBs not only interfere with virus spread but also increase the immune recognition of HIV-1 expressing cells.
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Affiliation(s)
- Christian Setz
- Institute of Virology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen 91054, Germany.
| | - Melanie Friedrich
- Institute of Virology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen 91054, Germany.
| | - Pia Rauch
- Institute of Virology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen 91054, Germany.
| | - Kirsten Fraedrich
- Institute of Virology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen 91054, Germany.
| | - Alina Matthaei
- Institute of Virology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen 91054, Germany.
| | - Maximilian Traxdorf
- Department of Otorhinolaryngology, Head and Neck Surgery, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen 91054, Germany.
| | - Ulrich Schubert
- Institute of Virology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen 91054, Germany.
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12
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de Bock CE, Hughes MR, Snyder K, Alley S, Sadeqzadeh E, Dun MD, McNagny KM, Molloy TJ, Hondermarck H, Thorne RF. Protein interaction screening identifies SH3RF1 as a new regulator of FAT1 protein levels. FEBS Lett 2017; 591:667-678. [PMID: 28129444 DOI: 10.1002/1873-3468.12569] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Revised: 01/11/2017] [Accepted: 01/23/2017] [Indexed: 01/14/2023]
Abstract
Mutations and ectopic FAT1 cadherin expression are implicated in a broad spectrum of diseases ranging from developmental disorders to cancer. The regulation of FAT1 and its downstream signalling pathways remain incompletely understood. We hypothesized that identification of additional proteins interacting with the FAT1 cytoplasmic tail would further delineate its regulation and function. A yeast two-hybrid library screen carried out against the juxtamembrane region of the cytoplasmic tail of FAT1 identified the E3 ubiquitin-protein ligase SH3RF1 as the most frequently recovered protein-binding partner. Ablating SH3RF1 using siRNA increased cellular FAT1 protein levels and stabilized expression at the cell surface, while overexpression of SH3RF1 reduced FAT1 levels. We conclude that SH3RF1 acts as a negative post-translational regulator of FAT1 levels.
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Affiliation(s)
- Charles E de Bock
- VIB Center for the Biology of Disease, Leuven, Belgium.,Hunter Cancer Research Alliance, University of Newcastle, Callaghan, Australia
| | - Michael R Hughes
- The Biomedical Research Centre, University of British Columbia, Vancouver, Canada
| | - Kimberly Snyder
- The Biomedical Research Centre, University of British Columbia, Vancouver, Canada
| | - Steven Alley
- Hunter Cancer Research Alliance, University of Newcastle, Callaghan, Australia.,School of Environmental and Life Sciences, University of Newcastle, Callaghan, Australia
| | - Elham Sadeqzadeh
- Hunter Cancer Research Alliance, University of Newcastle, Callaghan, Australia.,School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, Australia
| | - Matt D Dun
- Hunter Cancer Research Alliance, University of Newcastle, Callaghan, Australia.,School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, Australia
| | - Kelly M McNagny
- The Biomedical Research Centre, University of British Columbia, Vancouver, Canada
| | - Timothy J Molloy
- The Kinghorn Cancer Centre and Cancer Research Program, Garvan Institute of Medical Research, Darlinghurst, Australia
| | - Hubert Hondermarck
- Hunter Cancer Research Alliance, University of Newcastle, Callaghan, Australia.,School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, Australia
| | - Rick F Thorne
- Hunter Cancer Research Alliance, University of Newcastle, Callaghan, Australia.,School of Environmental and Life Sciences, University of Newcastle, Callaghan, Australia
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Sabino Cunha M, Lima Sampaio T, Peterlin BM, Jesus da Costa L. A Truncated Nef Peptide from SIVcpz Inhibits the Production of HIV-1 Infectious Progeny. Viruses 2016; 8:v8070189. [PMID: 27399760 PMCID: PMC4974524 DOI: 10.3390/v8070189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 06/08/2016] [Accepted: 06/14/2016] [Indexed: 12/02/2022] Open
Abstract
Nef proteins from all primate Lentiviruses, including the simian immunodeficiency virus of chimpanzees (SIVcpz), increase viral progeny infectivity. However, the function of Nef involved with the increase in viral infectivity is still not completely understood. Nonetheless, until now, studies investigating the functions of Nef from SIVcpz have been conducted in the context of the HIV-1 proviruses. In an attempt to investigate the role played by Nef during the replication cycle of an SIVcpz, a Nef-defective derivative was obtained from the SIVcpzWTGab2 clone by introducing a frame shift mutation at a unique restriction site within the nef sequence. This nef-deleted clone expresses an N-terminal 74-amino acid truncated peptide of Nef and was named SIVcpz-tNef. We found that the SIVcpz-tNef does not behave as a classic nef-deleted HIV-1 or simian immunodeficiency virus of macaques SIVmac. Markedly, SIVcpz-tNef progeny from both Hek-293T and Molt producer cells were completely non-infectious. Moreover, the loss in infectivity of SIVcpz-tNef correlated with the inhibition of Gag and GagPol processing. A marked accumulation of Gag and very low levels of reverse transcriptase were detected in viral lysates. Furthermore, these observations were reproduced once the tNef peptide was expressed in trans both in SIVcpzΔNef and HIV-1WT expressing cells, demonstrating that the truncated peptide is a dominant negative for viral processing and infectivity for both SIVcpz and HIV-1. We demonstrated that the truncated Nef peptide binds to GagPol outside the protease region and by doing so probably blocks processing of both GagPol and Gag precursors at a very early stage. This study demonstrates for the first time that naturally-occurring Nef peptides can potently block lentiviral processing and infectivity.
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Affiliation(s)
- Marcela Sabino Cunha
- Departamento de Virologia-Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho 373-CCS-Bloco I, Rio de Janeiro 21941-902, Brazil.
| | - Thatiane Lima Sampaio
- Departamento de Virologia-Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho 373-CCS-Bloco I, Rio de Janeiro 21941-902, Brazil.
| | - B Matija Peterlin
- Departments of Medicine, Microbiology and Immunology, University of California, San Francisco, 533 Parnassus Avenue, San Francisco, CA 94143, USA.
| | - Luciana Jesus da Costa
- Departamento de Virologia-Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho 373-CCS-Bloco I, Rio de Janeiro 21941-902, Brazil.
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Chapter Five - Ubiquitination of Ion Channels and Transporters. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2016; 141:161-223. [DOI: 10.1016/bs.pmbts.2016.02.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Abstract
UNLABELLED HIV-1 modulates key host cellular pathways for successful replication and pathogenesis through viral proteins. By evaluating the hijacking of the host ubiquitination pathway by HIV-1 at the whole-cell level, we now show major perturbations in the ubiquitinated pool of the host proteins post-HIV-1 infection. Our overexpression- and infection-based studies of T cells with wild-type and mutant HIV-1 proviral constructs showed that Vpr is necessary and sufficient for reducing whole-cell ubiquitination. Mutagenic analysis revealed that the three leucine-rich helical regions of Vpr are critical for this novel function of Vpr, which was independent of its other known cellular functions. We also validated that this effect of Vpr was conserved among different subtypes (subtypes B and C) and circulating recombinants from Northern India. Finally, we establish that this phenomenon is involved in HIV-1-mediated diversion of host ubiquitination machinery specifically toward the degradation of various restriction factors during viral pathogenesis. IMPORTANCE HIV-1 is known to rely heavily on modulation of the host ubiquitin pathway, particularly for counteraction of antiretroviral restriction factors, i.e., APOBEC3G, UNG2, and BST-2, etc.; viral assembly; and release. Reports to date have focused on the molecular hijacking of the ubiquitin machinery by HIV-1 at the level of E3 ligases. Interaction of a viral protein with an E3 ligase alters its specificity to bring about selective protein ubiquitination. However, in the case of infection, multiple viral proteins can interact with this multienzyme pathway at various levels, making it much more complicated. Here, we have addressed the manipulation of ubiquitination at the whole-cell level post-HIV-1 infection. Our results show that HIV-1 Vpr is necessary and sufficient to bring about the redirection of the host ubiquitin pathway toward HIV-1-specific outcomes. We also show that the three leucine-rich helical regions of Vpr are critical for this effect and that this ability of Vpr is conserved across circulating recombinants. Our work, the first of its kind, provides novel insight into the regulation of the ubiquitin system at the whole-cell level by HIV-1.
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Klinger PP, Schubert U. The ubiquitin–proteasome system in HIV replication: potential targets for antiretroviral therapy. Expert Rev Anti Infect Ther 2014; 3:61-79. [PMID: 15757458 DOI: 10.1586/14787210.3.1.61] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Since the discovery of HIV approximately 20 years ago, more than 60 million individuals have been infected, and AIDS still remains one of the most devastating diseases humankind has ever faced. Unfortunately, there is little hope that an effective vaccine will be developed in the near future. Current antiretroviral treatment is based on drugs that either target the viral enzymes (protease and reverse transcriptase) or the attachment and entry of the virus. Although the introduction of highly active antiretroviral therapy in the mid-1990s has led to a profound reduction in HIV-related morbidity and mortality, the complete eradication of the virus from infected individuals has never been achieved. In addition, these antiviral drugs can induce serious adverse effects, particularly when administered in combination over prolonged treatment periods. A further drawback to these treatments is that with the high mutation rate of HIV, drug-resistant mutants are evolving, particularly when antiretroviral treatment only suppresses virus replication to marginal levels in latently infected cells making up the virus reservoirs in vivo. Cellular genes have much lower mutation rates, and drug-mediated modulation of specific cellular pathways represents an attractive antiviral strategy. Recent findings showing that proteasome inhibitors interfere with budding, maturation and infectivity of HIV have triggered intensive investigation of the hitherto unappreciated function of the ubiquitin-proteasome system in HIV replication. It was also observed that, like several other retroviruses, HIV-1 virions contain a small amount of mono-ubiquitinylated Gag proteins. Currently, two E3-type ubiquitin ligases, in addition to one E3-like protein, have been identified as regulators of HIV budding. These ligases might represent interesting targets for therapeutic intervention.
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Affiliation(s)
- Patricia P Klinger
- University of Erlangen-Nuremberg, Institute of Clinical and Molecular Virology, Schlossgarten 4, 91054 Erlangen, Germany
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Bohl CR, Abrahamyan LG, Wood C. Human Ubc9 is involved in intracellular HIV-1 Env stability after trafficking out of the trans-Golgi network in a Gag dependent manner. PLoS One 2013; 8:e69359. [PMID: 23861967 PMCID: PMC3704627 DOI: 10.1371/journal.pone.0069359] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 06/07/2013] [Indexed: 01/03/2023] Open
Abstract
The cellular E2 Sumo conjugase, Ubc9 interacts with HIV-1 Gag, and is important for the assembly of infectious HIV-1 virions. In the previous study we demonstrated that in the absence of Ubc9, a defect in virion assembly was associated with decreased levels of mature intracellular Envelope (Env) that affected Env incorporation into virions and virion infectivity. We have further characterized the effect of Ubc9 knockdown on HIV Env processing and assembly. We found that gp160 stability in the endoplasmic reticulum (ER) and its trafficking to the trans-Golgi network (TGN) were unaffected, indicating that the decreased intracellular mature Env levels in Ubc9-depleted cells were due to a selective degradation of mature Env gp120 after cleavage from gp160 and trafficked out of the TGN. Decreased levels of Gag and mature Env were found to be associated with the plasma membrane and lipid rafts, which suggest that these viral proteins were not trafficked correctly to the assembly site. Intracellular gp120 were partially rescued when treated with a combination of lysosome inhibitors. Taken together our results suggest that in the absence of Ubc9, gp120 is preferentially degraded in the lysosomes likely before trafficking to assembly sites leading to the production of defective virions. This study provides further insight in the processing and packaging of the HIV-1 gp120 into mature HIV-1 virions.
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Affiliation(s)
- Christopher R. Bohl
- Nebraska Center for Virology and the School of Biological Sciences, University of Nebraska, Lincoln, Lincoln, Nebraska, United States of America
| | - Levon G. Abrahamyan
- Nebraska Center for Virology and the School of Biological Sciences, University of Nebraska, Lincoln, Lincoln, Nebraska, United States of America
| | - Charles Wood
- Nebraska Center for Virology and the School of Biological Sciences, University of Nebraska, Lincoln, Lincoln, Nebraska, United States of America
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HIV Assembly and Budding: Ca(2+) Signaling and Non-ESCRT Proteins Set the Stage. Mol Biol Int 2012; 2012:851670. [PMID: 22761998 PMCID: PMC3384956 DOI: 10.1155/2012/851670] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 03/26/2012] [Indexed: 12/16/2022] Open
Abstract
More than a decade has elapsed since the link between the endosomal sorting complex required for transport (ESCRT) machinery and HIV-1 protein trafficking and budding was first identified. L domains in HIV-1 Gag mediate recruitment of ESCRT which function in bud abscission releasing the viral particle from the host cell. Beyond virus budding, the ESCRT machinery is also involved in the endocytic pathway, cytokinesis, and autophagy. In the past few years, the number of non-ESCRT host proteins shown to be required in the assembly process has also grown. In this paper, we highlight the role of recently identified cellular factors that link ESCRT machinery to calcium signaling machinery and we suggest that this liaison contributes to setting the stage for productive ESCRT recruitment and mediation of abscission. Parallel paradigms for non-ESCRT roles in virus budding and cytokinesis will be discussed.
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Biard-Piechaczyk M, Borel S, Espert L, de Bettignies G, Coux O. HIV-1, ubiquitin and ubiquitin-like proteins: the dialectic interactions of a virus with a sophisticated network of post-translational modifications. Biol Cell 2012; 104:165-87. [PMID: 22188301 DOI: 10.1111/boc.201100112] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Accepted: 12/14/2011] [Indexed: 11/26/2022]
Abstract
The modification of intracellular proteins by ubiquitin (Ub) and ubiquitin-like (UbL) proteins is a central mechanism for regulating and fine-tuning all cellular processes. Indeed, these modifications are widely used to control the stability, activity and localisation of many key proteins and, therefore, they are instrumental in regulating cellular functions as diverse as protein degradation, cell signalling, vesicle trafficking and immune response. It is thus no surprise that pathogens in general, and viruses in particular, have developed multiple strategies to either counteract or exploit the complex mechanisms mediated by the Ub and UbL protein conjugation pathways. The aim of this review is to provide an overview on the intricate and conflicting relationships that intimately link HIV-1 and these sophisticated systems of post-translational modifications.
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Affiliation(s)
- Martine Biard-Piechaczyk
- Centre d'étude d'agents Pathogènes et Biotechnologies pour la Santé (CPBS-CNRS), Montpellier Cedex 5, France.
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Abstract
Assembly and release of human immunodeficiency virus type 1 (HIV-1) particles is mediated by the viral Gag polyprotein precursor. Gag is synthesized in the cytosol and rapidly translocates to membrane to orchestrate particle production. The cell biology of HIV-1 Gag trafficking is currently one of the least understood aspects of HIV-1 replication. In this review, we highlight the current understanding of the cellular machinery involved in Gag trafficking and virus assembly.
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Affiliation(s)
- Muthukumar Balasubramaniam
- Virus-Cell Interaction Section, HIV Drug Resistance Program, National Cancer Institute, Frederick, Maryland
| | - Eric O. Freed
- Virus-Cell Interaction Section, HIV Drug Resistance Program, National Cancer Institute, Frederick, Maryland
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Abstract
The cellular ALIX protein functions within the ESCRT pathway to facilitate intralumenal endosomal vesicle formation, the abscission stage of cytokinesis, and enveloped virus budding. Here, we report that the C-terminal proline-rich region (PRR) of ALIX folds back against the upstream domains and auto-inhibits V domain binding to viral late domains. Mutations designed to destabilize the closed conformation of the V domain opened the V domain, increased ALIX membrane association, and enhanced virus budding. These observations support a model in which ALIX activation requires dissociation of the autoinhibitory PRR and opening of the V domain arms.
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Cooper J, Liu L, Woodruff EA, Taylor HE, Goodwin JS, D'Aquila RT, Spearman P, Hildreth JEK, Dong X. Filamin A protein interacts with human immunodeficiency virus type 1 Gag protein and contributes to productive particle assembly. J Biol Chem 2011; 286:28498-510. [PMID: 21705339 DOI: 10.1074/jbc.m111.239053] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
HIV-1 Gag precursor directs virus particle assembly and release. In a search for Gag-interacting proteins that are involved in late stages of the HIV-1 replication cycle, we performed yeast two-hybrid screening against a human cDNA library and identified the non-muscle actin filament cross-linking protein filamin A as a novel Gag binding partner. The 280-kDa filamin A regulates cortical actin network dynamics and participates in the anchoring of membrane proteins to the actin cytoskeleton. Recent studies have shown that filamin A facilitates HIV-1 cell-to-cell transmission by binding to HIV receptors and coreceptors and regulating their clustering on the target cell surface. Here we report a novel role for filamin A in HIV-1 Gag intracellular trafficking. We demonstrate that filamin A interacts with the capsid domain of HIV-1 Gag and that this interaction is involved in particle release in a productive manner. Disruption of this interaction eliminated Gag localization at the plasma membrane and induced Gag accumulation within internal compartments. Moreover, blocking clathrin-dependent endocytic pathways did not relieve the restriction to particle release induced by filamin A depletion. These results suggest that filamin A is involved in the distinct step of the Gag trafficking pathway. The discovery of the Gag-filamin A interaction may provide a new therapeutic target for the treatment of HIV infection.
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Affiliation(s)
- JoAnn Cooper
- Center for AIDS Health Disparities Research, Department of Microbiology, and Immunology, Meharry Medical College, Nashville, Tennessee 37208, USA
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Joshi A, Garg H, Ablan SD, Freed EO. Evidence of a role for soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) machinery in HIV-1 assembly and release. J Biol Chem 2011; 286:29861-71. [PMID: 21680744 DOI: 10.1074/jbc.m111.241521] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Retrovirus assembly is a complex process that requires the orchestrated participation of viral components and host-cell factors. The concerted movement of different viral proteins to specific sites in the plasma membrane allows for virus particle assembly and ultimately budding and maturation of infectious virions. The soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins constitute the minimal machinery that catalyzes the fusion of intracellular vesicles with the plasma membrane, thus regulating protein trafficking. Using siRNA and dominant negative approaches we demonstrate here that generalized disruption of the host SNARE machinery results in a significant reduction in human immunodeficiency virus type 1 (HIV-1) and equine infectious anemia virus particle production. Further analysis of the mechanism involved revealed a defect at the level of HIV-1 Gag localization to the plasma membrane. Our findings demonstrate for the first time a role of SNARE proteins in HIV-1 assembly and release, likely by affecting cellular trafficking pathways required for Gag transport and association with the plasma membrane.
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Affiliation(s)
- Anjali Joshi
- Center of Excellence for Infectious Diseases, Department of Biomedical Sciences, Texas Tech University Health Sciences Center, El Paso, Texas 79905, USA.
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Tsuda M, Kawaida R, Kobayashi K, Shinagawa A, Sawada T, Yamada R, Yamamoto K, Aigaki T. POSH promotes cell survival inDrosophilaand in human RASF cells. FEBS Lett 2010; 584:4689-94. [DOI: 10.1016/j.febslet.2010.10.048] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Accepted: 10/20/2010] [Indexed: 10/18/2022]
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Keil JM, Shen Z, Briggs SP, Patrick GN. Regulation of STIM1 and SOCE by the ubiquitin-proteasome system (UPS). PLoS One 2010; 5:e13465. [PMID: 20976103 PMCID: PMC2956693 DOI: 10.1371/journal.pone.0013465] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2010] [Accepted: 09/07/2010] [Indexed: 12/02/2022] Open
Abstract
The ubiquitin proteasome system (UPS) mediates the majority of protein degradation in eukaryotic cells. The UPS has recently emerged as a key degradation pathway involved in synapse development and function. In order to better understand the function of the UPS at synapses we utilized a genetic and proteomic approach to isolate and identify novel candidate UPS substrates from biochemically purified synaptic membrane preparations. Using these methods, we have identified Stromal interacting molecule 1 (STIM1). STIM1 is as an endoplasmic reticulum (ER) calcium sensor that has been shown to regulate store-operated Ca2+ entry (SOCE). We have characterized STIM1 in neurons, finding STIM1 is expressed throughout development with stable, high expression in mature neurons. As in non-excitable cells, STIM1 is distributed in a membranous and punctate fashion in hippocampal neurons. In addition, a population of STIM1 was found to exist at synapses. Furthermore, using surface biotinylation and live-cell labeling methods, we detect a subpopulation of STIM1 on the surface of hippocampal neurons. The role of STIM1 as a regulator of SOCE has typically been examined in non-excitable cell types. Therefore, we examined the role of the UPS in STIM1 and SOCE function in HEK293 cells. While we find that STIM1 is ubiquitinated, its stability is not altered by proteasome inhibitors in cells under basal conditions or conditions that activate SOCE. However, we find that surface STIM1 levels and thapsigargin (TG)-induced SOCE are significantly increased in cells treated with proteasome inhibitors. Additionally, we find that the overexpression of POSH (Plenty of SH3′s), an E3 ubiquitin ligase recently shown to be involved in the regulation of Ca2+ homeostasis, leads to decreased STIM1 surface levels. Together, these results provide evidence for previously undescribed roles of the UPS in the regulation of STIM1 and SOCE function.
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Affiliation(s)
- Jeffrey M. Keil
- Section of Neurobiology, Department of Biological Sciences, University of California San Diego, La Jolla, California, United States of America
| | - Zhouxin Shen
- Section of Cell and Developmental Biology, Department of Biological Sciences, University of California San Diego, La Jolla, California, United States of America
| | - Steven P. Briggs
- Section of Cell and Developmental Biology, Department of Biological Sciences, University of California San Diego, La Jolla, California, United States of America
| | - Gentry N. Patrick
- Section of Neurobiology, Department of Biological Sciences, University of California San Diego, La Jolla, California, United States of America
- * E-mail:
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POSH is involved in Eiger-Basket (TNF-JNK) signaling and embryogenesis in Drosophila. J Genet Genomics 2010; 37:605-19. [DOI: 10.1016/s1673-8527(09)60080-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Revised: 06/07/2010] [Accepted: 06/17/2010] [Indexed: 01/08/2023]
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Abstract
Macrophages have been postulated to play an important role in the pathogenesis of HIV-1 infection. Their ability to cross the blood-brain barrier and their resistance to virus-induced cytopathic effects allows them to serve as reservoirs for long-term infection. Thus, exploring the mechanisms of virus transmission from macrophages to target cells such as other macrophages or T lymphocytes is central to our understanding of HIV-1 pathogenesis and progression to AIDS, and is vital to the development of vaccines and novel antiretroviral therapies. This review provides an overview of the current understanding of cell-cell transmission in macrophages.
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Joshi A, Nagashima K, Freed EO. Defects in cellular sorting and retroviral assembly induced by GGA overexpression. BMC Cell Biol 2009; 10:72. [PMID: 19788741 PMCID: PMC2760529 DOI: 10.1186/1471-2121-10-72] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2009] [Accepted: 09/29/2009] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND We previously demonstrated that overexpression of Golgi-localized, gamma-ear containing, Arf-binding (GGA) proteins inhibits retrovirus assembly and release by disrupting the function of endogenous ADP ribosylation factors (Arfs). GGA overexpression led to the formation of large, swollen vacuolar compartments, which in the case of GGA1 sequestered HIV-1 Gag. RESULTS In the current study, we extend our previous findings to characterize in depth the GGA-induced compartments and the determinants for retroviral Gag sequestration in these structures. We find that GGA-induced structures are derived from the Golgi and contain aggresome markers. GGA overexpression leads to defects in trafficking of transferrin receptor and recycling of cation-dependent mannose 6-phosphate receptor. Additionally, we find that compartments induced by GGA overexpression sequester Tsg101, poly-ubiquitin, and, in the case of GGA3, Hrs. Interestingly, brefeldin A treatment, which leads to the dissociation of endogenous GGAs from membranes, does not dissociate the GGA-induced compartments. GGA mutants that are defective in Arf binding and hence association with membranes also induce the formation of GGA-induced structures. Overexpression of ubiquitin reverses the formation of GGA-induced structures and partially rescues HIV-1 particle production. We found that in addition to HIV-1 Gag, equine infectious anemia virus Gag is also sequestered in GGA1-induced structures. The determinants in Gag responsible for sequestration map to the matrix domain, and recruitment to these structures is dependent on Gag membrane binding. CONCLUSION These data provide insights into the composition of structures induced by GGA overexpression and their ability to disrupt endosomal sorting and retroviral particle production.
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Affiliation(s)
- Anjali Joshi
- Virus-Cell Interaction Section, HIV Drug Resistance Program, National Cancer Institute at Frederick, Maryland, USA
- Department of Biomedical Sciences, Center of Excellence for Infectious Diseases, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX 79905, USA
| | - Kunio Nagashima
- Image Analysis Laboratory, Advanced Technology Program, SAIC-Frederick, National Cancer Institute at Frederick, Frederick, Maryland, USA
| | - Eric O Freed
- Virus-Cell Interaction Section, HIV Drug Resistance Program, National Cancer Institute at Frederick, Maryland, USA
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Votteler J, Iavnilovitch E, Fingrut O, Shemesh V, Taglicht D, Erez O, Sörgel S, Walther T, Bannert N, Schubert U, Reiss Y. Exploring the functional interaction between POSH and ALIX and the relevance to HIV-1 release. Retrovirology 2009. [PMCID: PMC2767081 DOI: 10.1186/1742-4690-6-s2-p92] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Christensen DE, Klevit RE. Dynamic interactions of proteins in complex networks: identifying the complete set of interacting E2s for functional investigation of E3-dependent protein ubiquitination. FEBS J 2009; 276:5381-9. [PMID: 19712108 DOI: 10.1111/j.1742-4658.2009.07249.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A ubiquitin ligase (E3) functions at the crossroad between ubiquitin activation and the attachment of ubiquitin to protein substrates. During this process, the E3 interacts with both a substrate and a ubiquitin-conjugating enzyme (E2). Although a major goal when investigating an E3 is to identify its substrates, recent evidence indicates that the E2 dictates the type of ubiquitin modification that will occur on the substrate. There are approximately 30 E2s identified in the human genome, many of which remain to be characterized. We found that the RING E3 BRCA1/BARD1 can interact with 10 different E2s. The ability of BRCA1 to interact with multiple E2s is likely to be a common feature among other RING and U-box E3s. We and others have also found that certain E2s show a preference for attaching either the first ubiquitin to a substrate lysine or ubiquitin to itself (chain building), suggesting that E2s may play a role in dictating product formation. Therefore, when investigating the functions of an E3 it is advisable to identify all E2s that interact with the E3 so that these can be used in E3-dependent substrate-ubiquitination assays. We describe a method used to identify all the E2s that interact with BRCA1. Defining the set of E2s that interact with other RING and U-box E3s will open the door for predictive models and lead to a better understand of substrate ubiquitination.
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Affiliation(s)
- Devin E Christensen
- Department of Biochemistry, University of Utah, Salt Lake City, UT 98195, USA
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Lin DH, Yue P, Pan CY, Sun P, Zhang X, Han Z, Roos M, Caplan M, Giebisch G, Wang WH. POSH stimulates the ubiquitination and the clathrin-independent endocytosis of ROMK1 channels. J Biol Chem 2009; 284:29614-24. [PMID: 19710010 DOI: 10.1074/jbc.m109.041582] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
POSH (plenty of SH3) is a scaffold protein that has been shown to act as an E3 ubiquitin ligase. Here we report that POSH stimulates the ubiquitination of Kir1.1 (ROMK) and enhances the internalization of this potassium channel. Immunostaining reveals the expression of POSH in the renal cortical collecting duct. Immunoprecipitation of renal tissue lysate with ROMK antibody and glutathione S-transferase pulldown experiments demonstrated the association between ROMK and POSH. Moreover, immunoprecipitation of lysates of HEK293T cells transfected with ROMK1 or with constructs encoding the ROMK-N terminus or ROMK1-C-Terminus demonstrated that POSH binds to ROMK1 on its N terminus. To study the effect of POSH on ROMK1 channels, we measured potassium currents with electrophysiological methods in HEK293T cells and in oocytes transfected or injected with ROMK1 and POSH. POSH decreased potassium currents, and the inhibitory effect of POSH on ROMK channels was dose-dependent. Biotinylation assay further showed that POSH decreased surface expression of ROMK channels in HEK293T cells transfected with ROMK1 and POSH. The effect of POSH on ROMK1 channels was specific because POSH did not inhibit sodium current in oocytes injected with ENaC-alpha, beta, and gamma subunits. Moreover, POSH still decreased the potassium current in oocytes injected with a ROMK1 mutant (R1Delta373-378), in which a clathrin-dependent tyrosine-based internalization signal residing between amino acid residues 373 and 378 is deleted. However, the inhibitory effect of POSH on ROMK channels was absent in cells expressing with dominant negative dynamin and POSHDeltaRING, in which the RING domain was deleted. Expression of POSH also increased the ubiquitination of ROMK1, whereas expression of POSHDeltaRING diminished its ubiquitination in HEK293T cells. The notion that POSH may serve as an E3 ubiquitin ligase is also supported by in vitro ubiquitination assays in which adding POSH increased the ROMK ubiquitination. We conclude that POSH inhibits ROMK channels by enhancing dynamin-dependent and clathrin-independent endocytosis and by stimulating ubiquitination of ROMK channels.
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Affiliation(s)
- Dao-Hong Lin
- Department of Pharmacology, New York Medical College, Valhalla, New York 10595, USA
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Human Ubc9 contributes to production of fully infectious human immunodeficiency virus type 1 virions. J Virol 2009; 83:10448-59. [PMID: 19640976 DOI: 10.1128/jvi.00237-09] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Ubc9 was identified as a cellular protein that interacts with the Gag protein of Mason-Pfizer monkey virus. We show here that Ubc9 also interacts with the human immunodeficiency virus type 1 (HIV-1) Gag protein and that their interaction is important for virus replication. Gag was found to colocalize with Ubc9 predominantly at perinuclear puncta. While cells in which Ubc9 expression was suppressed with RNA interference produced normal numbers of virions, these particles were 8- to 10-fold less infectious than those produced in the presence of Ubc9. The nature of this defect was assayed for dependence on Ubc9 during viral assembly, trafficking, and Env incorporation. The Gag-mediated assembly of virus particles and protease-mediated processing of Gag and Gag-Pol were unchanged in the absence of Ubc9. However, the stability of the cell-associated Env glycoprotein was decreased and Env incorporation into released virions was altered. Interestingly, overexpression of the Ubc9 trans-dominant-negative mutant C93A, which is a defective E2-SUMO-1 conjugase, suggests that this activity may not be required for interaction with Gag, virion assembly, or infectivity. This finding demonstrates that Ubc9 plays an important role in the production of infectious HIV-1 virions.
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Deficiency of niemann-pick type C-1 protein impairs release of human immunodeficiency virus type 1 and results in Gag accumulation in late endosomal/lysosomal compartments. J Virol 2009; 83:7982-95. [PMID: 19474101 DOI: 10.1128/jvi.00259-09] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) relies on cholesterol-laden lipid raft membrane microdomains for entry into and egress out of susceptible cells. In the present study, we examine the need for intracellular cholesterol trafficking pathways with respect to HIV-1 biogenesis using Niemann-Pick type C-1 (NPC1)-deficient (NPCD) cells, wherein these pathways are severely compromised, causing massive accumulation of cholesterol in late endosomal/lysosomal (LE/L) compartments. We have found that induction of an NPC disease-like phenotype through treatment of various cell types with the commonly used hydrophobic amine drug U18666A resulted in profound suppression of HIV-1 release. Further, NPCD Epstein-Barr virus-transformed B lymphocytes and fibroblasts from patients with NPC disease infected with a CD4-independent strain of HIV-1 or transfected with an HIV-1 proviral clone, respectively, replicated HIV-1 poorly compared to normal cells. Infection of the NPCD fibroblasts with a vesicular stomatitis virus G-pseudotyped strain of HIV-1 produced similar results, suggesting a postentry block to HIV-1 replication in these cells. Examination of these cells using confocal microscopy showed an accumulation and stabilization of Gag in LE/L compartments. Additionally, normal HIV-1 production could be restored in NPCD cells upon expression of a functional NPC1 protein, and overexpression of NPC1 increased HIV-1 release. Taken together, our findings demonstrate that intact intracellular cholesterol trafficking pathways mediated by NPC1 are needed for efficient HIV-1 production.
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Lehmann M, Milev MP, Abrahamyan L, Yao XJ, Pante N, Mouland AJ. Intracellular transport of human immunodeficiency virus type 1 genomic RNA and viral production are dependent on dynein motor function and late endosome positioning. J Biol Chem 2009; 284:14572-85. [PMID: 19286658 PMCID: PMC2682905 DOI: 10.1074/jbc.m808531200] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2008] [Revised: 03/03/2009] [Indexed: 11/06/2022] Open
Abstract
Our earlier work indicated that the human immunodeficiency virus type 1 (HIV-1) genomic RNA (vRNA) is trafficked to the microtubule-organizing center (MTOC) when heterogeneous nuclear ribonucleoprotein A2/B1 is depleted from cells. Also, Rab7-interacting lysosomal protein promoted dynein motor complex, late endosome and vRNA clustering at the MTOC suggesting that the dynein motor and late endosomes were involved in vRNA trafficking. To investigate the role of the dynein motor in vRNA trafficking, dynein motor function was disrupted by small interference RNA-mediated depletion of the dynein heavy chain or by p50/dynamitin overexpression. These treatments led to a marked relocalization of vRNA and viral structural protein Gag to the cell periphery with late endosomes and a severalfold increase in HIV-1 production. In contrast, rerouting vRNA to the MTOC reduced virus production. vRNA localization depended on Gag membrane association as shown using both myristoylation and Gag nucleocapsid domain proviral mutants. Furthermore, the cytoplasmic localization of vRNA and Gag was not attributable to intracellular or internalized endocytosed virus particles. Our results demonstrate that dynein motor function is important for regulating Gag and vRNA egress on endosomal membranes in the cytoplasm to directly impact on viral production.
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Affiliation(s)
- Martin Lehmann
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute for Medical Research, Quebec
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Votteler J, Iavnilovitch E, Fingrut O, Shemesh V, Taglicht D, Erez O, Sörgel S, Walther T, Bannert N, Schubert U, Reiss Y. Exploring the functional interaction between POSH and ALIX and the relevance to HIV-1 release. BMC BIOCHEMISTRY 2009; 10:12. [PMID: 19393081 PMCID: PMC2680910 DOI: 10.1186/1471-2091-10-12] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Accepted: 04/24/2009] [Indexed: 12/21/2022]
Abstract
BACKGROUND The ALG2-interacting protein X (ALIX)/AIP1 is an adaptor protein with multiple functions in intracellular protein trafficking that plays a central role in the biogenesis of enveloped viruses. The ubiquitin E3-ligase POSH (plenty of SH3) augments HIV-1 egress by facilitating the transport of Gag to the cell membrane. Recently, it was reported, that POSH interacts with ALIX and thereby enhances ALIX mediated phenotypes in Drosophila. RESULTS In this study we identified ALIX as a POSH ubiquitination substrate in human cells: POSH induces the ubiquitination of ALIX that is modified on several lysine residues in vivo and in vitro. This ubiquitination does not destabilize ALIX, suggesting a regulatory function. As it is well established that ALIX rescues virus release of L-domain mutant HIV-1, HIV-1DeltaPTAP, we demonstrated that wild type POSH, but not an ubiquitination inactive RING finger mutant (POSHV14A), substantially enhances ALIX-mediated release of infectious virions derived from HIV-1DeltaPTAP L-domain mutant (YPXnL-dependent HIV-1). In further agreement with the idea of a cooperative function of POSH and ALIX, mutating the YPXnL-ALIX binding site in Gag completely abrogated augmentation of virus release by overexpression of POSH. However, the effect of the POSH-mediated ubiquitination appears to be auxiliary, but not necessary, as silencing of POSH by RNAi does not disturb ALIX-augmentation of virus release. CONCLUSION Thus, the cumulative results identified ALIX as an ubiquitination substrate of POSH and indicate that POSH and ALIX cooperate to facilitate efficient virus release. However, while ALIX is obligatory for the release of YPXnL-dependent HIV-1, POSH, albeit rate-limiting, may be functionally interchangeable.
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Affiliation(s)
- Jörg Votteler
- Institute of Virology, Friedrich-Alexander University, Erlangen, Germany.
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Anx2 interacts with HIV-1 Gag at phosphatidylinositol (4,5) bisphosphate-containing lipid rafts and increases viral production in 293T cells. PLoS One 2009; 4:e5020. [PMID: 19325895 PMCID: PMC2657825 DOI: 10.1371/journal.pone.0005020] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Accepted: 02/24/2009] [Indexed: 01/12/2023] Open
Abstract
The neuronal damage characteristic of HIV-1-mediated CNS diseases is inflicted by HIV-1 infected brain macrophages. Several steps of viral replication, including assembly and budding, differ between macrophages and T cells; it is likely that cell-specific host factors mediate these differences. We previously defined Annexin 2 (Anx2) as an HIV Gag binding partner in human monocyte-derived macrophages (MDMs) that promotes proper viral assembly. Anx2, a calcium-dependent membrane-binding protein that can aggregate phospholipid-containing lipid rafts, is expressed to high levels in macrophages, but not in T lymphocytes or the 293T cell line. Here, we use bimolecular fluorescence complementation in the 293T cell model to demonstrate that Anx2 and HIV-1 Gag interact at the phosphatidylinositol (4,5) bisphosphate-containing lipid raft membrane domains at which Gag mediates viral assembly. Furthermore, we demonstrate that Anx2 expression in 293T cells increases Gag processing and HIV-1 production. These data provide new evidence that Anx2, by interacting with Gag at the membranes that support viral assembly, functions in the late stages of HIV-1 replication.
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Nishi M, Ryo A, Tsurutani N, Ohba K, Sawasaki T, Morishita R, Perrem K, Aoki I, Morikawa Y, Yamamoto N. Requirement for microtubule integrity in the SOCS1-mediated intracellular dynamics of HIV-1 Gag. FEBS Lett 2009; 583:1243-50. [PMID: 19327355 DOI: 10.1016/j.febslet.2009.03.041] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2008] [Revised: 03/16/2009] [Accepted: 03/18/2009] [Indexed: 11/17/2022]
Abstract
Suppressor of cytokine signaling 1 (SOCS1) is a recently identified host factor that positively regulates the intracellular trafficking and stability of HIV-1 Gag. We here examine the molecular mechanism by which SOCS1 regulates intercellular Gag trafficking and virus particle production. We find that SOCS1 colocalizes with Gag along the microtubule network and promotes microtubule stability. SOCS1 also increases the amount of Gag associated with microtubules. Both nocodazole treatment and the expression of the microtubule-destabilizing protein, stathmin, inhibit the enhancement of HIV-1 particle production by SOCS1. SOCS1 facilitates Gag ubiquitination and the co-expression of a dominant-negative ubiquitin significantly inhibits the association of Gag with microtubules. We thus propose that the microtubule network plays a role in SOCS1-mediated HIV-1 Gag transport and virus particle formation.
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Affiliation(s)
- Mayuko Nishi
- AIDS Research Center, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo, Japan
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Calistri A, Salata C, Parolin C, Palù G. Role of multivesicular bodies and their components in the egress of enveloped RNA viruses. Rev Med Virol 2009; 19:31-45. [PMID: 18618839 DOI: 10.1002/rmv.588] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
As an enveloped virus buds, the nascent viral capsid becomes wrapped in a plasma membrane-derived lipid envelope, and a membrane fission event is thus necessary to separate the virion from the host cell. This membrane fission event is well characterised in the case of enveloped RNA viruses, where it is promoted by late assembly domains (L-domains) present at the level of specific viral structural proteins. Research conducted over the past 10 years has demonstrated that L-domains represent docking sites for cellular proteins essential for the biogenesis of a cellular organelle, the multivesicular body (MVB). In this way, enveloped RNA viruses hijack the MVB components to the cellular site where the budding is executed. This review will focus on the cellular machinery exploited by enveloped RNA viruses in order to be released from infected cells. The role of ubiquitin and lipids in viral budding will also be discussed.
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Affiliation(s)
- A Calistri
- Department of Histology, Microbiology and Medical Biotechnologies, University of Padova, Padova, Italy
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39
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Abstract
Virus particle formation of HIV-1 is a multi-step process driven by a viral structural protein Gag. This process takes place at the plasma membrane in most cell types. However, the pathway that directs Gag to the plasma membrane has recently come under intense scrutiny because of its importance in production of progeny virions as well as virus transmission at cell-cell contacts. This review highlights recent advances in our current understanding of mechanisms that traffic and localize Gag to the plasma membrane. In addition, findings on Gag association with specific plasma membrane domains are discussed in light of potential roles in cell-to-cell transmission.
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40
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Taylor J, Chung KH, Figueroa C, Zurawski J, Dickson HM, Brace EJ, Avery AW, Turner DL, Vojtek AB. The scaffold protein POSH regulates axon outgrowth. Mol Biol Cell 2008; 19:5181-92. [PMID: 18829867 PMCID: PMC2592661 DOI: 10.1091/mbc.e08-02-0231] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2008] [Revised: 08/28/2008] [Accepted: 09/23/2008] [Indexed: 12/13/2022] Open
Abstract
How scaffold proteins integrate signaling pathways with cytoskeletal components to drive axon outgrowth is not well understood. We report here that the multidomain scaffold protein Plenty of SH3s (POSH) regulates axon outgrowth. Reduction of POSH function by RNA interference (RNAi) enhances axon outgrowth in differentiating mouse primary cortical neurons and in neurons derived from mouse P19 cells, suggesting POSH negatively regulates axon outgrowth. Complementation analysis reveals a requirement for the third Src homology (SH) 3 domain of POSH, and we find that the actomyosin regulatory protein Shroom3 interacts with this domain of POSH. Inhibition of Shroom3 expression by RNAi leads to increased process lengths, as observed for POSH RNAi, suggesting that POSH and Shroom function together to inhibit process outgrowth. Complementation analysis and interference of protein function by dominant-negative approaches suggest that Shroom3 recruits Rho kinase to inhibit process outgrowth. Furthermore, inhibition of myosin II function reverses the POSH or Shroom3 RNAi phenotype, indicating a role for myosin II regulation as a target of the POSH-Shroom complex. Collectively, these results suggest that the molecular scaffold protein POSH assembles an inhibitory complex that links to the actin-myosin network to regulate neuronal process outgrowth.
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Affiliation(s)
| | - Kwan-Ho Chung
- Program in Neuroscience, and
- Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI 48109
| | | | | | | | | | | | - David L. Turner
- *Department of Biological Chemistry
- Program in Neuroscience, and
- Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI 48109
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Strasner AB, Natarajan M, Doman T, Key D, August A, Henderson AJ. The Src kinase Lck facilitates assembly of HIV-1 at the plasma membrane. THE JOURNAL OF IMMUNOLOGY 2008; 181:3706-13. [PMID: 18714047 DOI: 10.4049/jimmunol.181.5.3706] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
HIV type 1 (HIV-1) assembly and egress are driven by the viral protein Gag and occur at the plasma membrane in T cells. Recent evidence indicates that secretory vesicles and machinery are essential components of virus packaging in both T cells and macrophages. However, the pathways and cellular mediators of Gag targeting to the plasma membrane are not well characterized. Lck, a lymphoid specific Src kinase critical for T cell activation, is found in the plasma membrane as well as various intracellular compartments and it has been suggested to influence HIV-1 replication. To investigate Lck as a potential regulator of Gag targeting, we assessed HIV-1 replication and Gag-induced virus-like particle release in the presence and absence of Lck. Release of HIV-1 and virus-like particles was reduced in the absence of Lck. This decrease in replication was not due to altered HIV-1 infection, transcription or protein translation. However, in T cells lacking Lck, HIV-1 accumulated intracellularly. In addition, expressing Lck in HeLa cells promoted HIV-1 Gag plasma membrane localization. Palmitoylation of the Lck unique domain, which is essential for directing Lck to the plasma membrane, was critical for its effect on HIV-1 replication. Furthermore, HIV-1 Gag directly interacted with the Lck unique domain in the context of infected cells. These results indicate that Lck plays a key role in targeting HIV-1 Gag to the plasma membrane in T cells.
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Affiliation(s)
- Amy B Strasner
- Intergrated Bioscience Program in Immunobiology, Huck Institute of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
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Murakami T. Roles of the interactions between Env and Gag proteins in the HIV-1 replication cycle. Microbiol Immunol 2008; 52:287-95. [PMID: 18557900 DOI: 10.1111/j.1348-0421.2008.00008.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The Env and Gag proteins of HIV-1 are the two major structural proteins of this retrovirus. The interactions between Env and Gag proteins and their regulation in HIV-1 are required for several steps of the replication cycle, involving not only virus assembly, specifically Env incorporation, but also entry steps after virus maturation. A large number of host factors and certain membrane microdomains appear to engage both in transport/trafficking of Env and/or Gag proteins, and in the interactions of these two proteins. The present review briefly summarizes our current knowledge regarding the roles of the interactions between Env and Gag proteins in the virus replication cycle.
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Chan WT, Sherer NM, Uchil PD, Novak EK, Swank RT, Mothes W. Murine leukemia virus spreading in mice impaired in the biogenesis of secretory lysosomes and Ca2+-regulated exocytosis. PLoS One 2008; 3:e2713. [PMID: 18629000 PMCID: PMC2443282 DOI: 10.1371/journal.pone.0002713] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Accepted: 06/24/2008] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Retroviruses have been observed to bud intracellularly into multivesicular bodies (MVB), in addition to the plasma membrane. Release from MVB is thought to occur by Ca(2+)-regulated fusion with the plasma membrane. PRINCIPAL FINDINGS To address the role of the MVB pathway in replication of the murine leukemia virus (MLV) we took advantage of mouse models for the Hermansky-Pudlak syndrome (HPS) and Griscelli syndrome. In humans, these disorders are characterized by hypopigmentation and immunological alterations that are caused by defects in the biogenesis and trafficking of MVBs and other lysosome related organelles. Neonatal mice for these disease models lacking functional AP-3, Rab27A and BLOC factors were infected with Moloney MLV and the spread of virus into bone marrow, spleen and thymus was monitored. We found a moderate reduction in MLV infection levels in most mutant mice, which differed by less than two-fold compared to wild-type mice. In vitro, MLV release form bone-marrow derived macrophages was slightly enhanced. Finally, we found no evidence for a Ca(2+)-regulated release pathway in vitro. Furthermore, MLV replication was only moderately affected in mice lacking Synaptotagmin VII, a Ca(2+)-sensor regulating lysosome fusion with the plasma membrane. CONCLUSIONS Given that MLV spreading in mice depends on multiple rounds of replication even moderate reduction of virus release at the cellular level would accumulate and lead to a significant effect over time. Thus our in vivo and in vitro data collectively argue against an essential role for a MVB- and secretory lysosome-mediated pathway in the egress of MLV.
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Affiliation(s)
- Wai-Tsing Chan
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Nathan M. Sherer
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Pradeep D. Uchil
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Edward K. Novak
- Department of Molecular and Cellular Biology, Roswell Park Cancer Institute, Buffalo, New York, United States of America
| | - Richard T. Swank
- Department of Molecular and Cellular Biology, Roswell Park Cancer Institute, Buffalo, New York, United States of America
| | - Walther Mothes
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
- * E-mail:
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Votteler J, Schubert U. Ubiquitin ligases as therapeutic targets in HIV-1 infection. Expert Opin Ther Targets 2008; 12:131-43. [PMID: 18208363 DOI: 10.1517/14728222.12.2.131] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Introduction of highly active antiretroviral therapy has led to a profound reduction in human immunodeficiency virus (HIV) related mortality; although, the complete eradication of the virus from infected individuals has never been achieved. In addition, due to the high mutation and evolution rate, drug-resistant viruses are continuously emerging. OBJECTIVE Genetically more stable cellular pathways represent attractive targets for innovative antiviral strategies, especially the ubiquitin proteasome system, which regulates various steps in the HIV replication cycle. METHODS This review focuses on certain interactions of HIV and E3 ligases as a major player in the ubiquitin proteasome system. RESULTS/CONCLUSION Due to the importance in HIV replication, and together with the high substrate specificity, E3 ligases can be considered as bona fide targets to interfere with HIV infection.
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Affiliation(s)
- Jörg Votteler
- University of Erlangen-Nuremberg, Institute of Clinical and Molecular Virology, Schlossgarten 4, 91054 Erlangen, Germany.
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45
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TULA proteins bind to ABCE-1, a host factor of HIV-1 assembly, and inhibit HIV-1 biogenesis in a UBA-dependent fashion. Virology 2008; 372:10-23. [DOI: 10.1016/j.virol.2007.10.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2007] [Revised: 07/09/2007] [Accepted: 10/11/2007] [Indexed: 11/20/2022]
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Abstract
Virus particle formation of HIV-1 is driven by the viral structural protein Gag. In most cell types including T cells, Gag assembles into virus particles at the plasma membrane whereas, in HIV-1-infected macrophages, Gag and virus particles have been shown to accumulate in intracellular vesicles. At the moment, what causes this difference between cell types remains unknown. However, recent findings on the relationships between Gag and the cellular membrane system have substantially increased our understanding of the mechanisms by which sites of virus assembly are determined. I will review our current knowledge regarding the roles played by endosomal trafficking pathways, membrane microdomains, and plasma membrane lipids, and discuss the physiological significance of the interactions between Gag and specific membrane structures.
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47
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SOCS1 is an inducible host factor during HIV-1 infection and regulates the intracellular trafficking and stability of HIV-1 Gag. Proc Natl Acad Sci U S A 2008; 105:294-9. [PMID: 18172216 DOI: 10.1073/pnas.0704831105] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) utilizes the macromolecular machinery of the infected host cell to produce progeny virus. The discovery of cellular factors that participate in HIV-1 replication pathways has provided further insight into the molecular basis of virus-host cell interactions. Here, we report that the suppressor of cytokine signaling 1 (SOCS1) is an inducible host factor during HIV-1 infection and regulates the late stages of the HIV-1 replication pathway. SOCS1 can directly bind to the matrix and nucleocapsid regions of the HIV-1 p55 Gag polyprotein and enhance its stability and trafficking, resulting in the efficient production of HIV-1 particles via an IFN signaling-independent mechanism. The depletion of SOCS1 by siRNA reduces both the targeted trafficking and assembly of HIV-1 Gag, resulting in its accumulation as perinuclear solid aggregates that are eventually subjected to lysosomal degradation. These results together indicate that SOCS1 is a crucial host factor that regulates the intracellular dynamism of HIV-1 Gag and could therefore be a potential new therapeutic target for AIDS and its related disorders.
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48
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Duffield A, Caplan MJ, Muth TR. Chapter 4 Protein Trafficking in Polarized Cells. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 270:145-79. [DOI: 10.1016/s1937-6448(08)01404-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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49
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Guédat P, Colland F. Patented small molecule inhibitors in the ubiquitin proteasome system. BMC BIOCHEMISTRY 2007; 8 Suppl 1:S14. [PMID: 18047738 PMCID: PMC2106365 DOI: 10.1186/1471-2091-8-s1-s14] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Deregulation of the ubiquitin proteasome system (UPS) has been implicated in the pathogenesis of many human diseases, including cancer and neurodegenerative disorders. The recent approval of the proteasome inhibitor Velcade® (bortezomib) for the treatment of multiple myeloma and mantle cell lymphoma establishes this system as a valid target for cancer treatment. We review here new patented proteasome inhibitors and patented small molecule inhibitors targeting more specific UPS components, such as E3 ubiquitin ligases and deubiquitylating enzymes. Publication history: Republished from Current BioData's Targeted Proteins database (TPdb; ).
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50
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Shoji-Kawata S, Zhong Q, Kameoka M, Iwabu Y, Sapsutthipas S, Luftig RB, Ikuta K. The RING finger ubiquitin ligase RNF125/TRAC-1 down-modulates HIV-1 replication in primary human peripheral blood mononuclear cells. Virology 2007; 368:191-204. [PMID: 17643463 DOI: 10.1016/j.virol.2007.06.028] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2007] [Revised: 06/04/2007] [Accepted: 06/19/2007] [Indexed: 11/27/2022]
Abstract
CXCR4-using HIV-1 was previously shown to replicate more efficiently in a healthy donor-derived CD4(+) CD38(+) than in a CD4(+) CD38(-) T-cell subset after stimulation with interleukin (IL)-4. Here, we identified 3 cellular genes, which were expressed to a higher level in an IL-4-stimulated CD38(-) subset. One of the 3 genes, RNF125/TRAC-1, was involved in the down-regulation of HIV-1 replication not only in cell lines, but also in peripheral blood mononuclear cells. RNF125/TRAC-1 bears the RING finger domain, important for E3 ubiquitin protein ligase. Mutations in this domain of RNF125/TRAC-1 led to the loss of HIV-1 down-modulatory activity, suggesting that E3 ligase activity is necessary. In addition, the results of Northern blotting and reporter gene analysis indicated that RNF125/TRAC-1 function occurs at the viral transcription step. These results suggest that RNF125/TRAC-1 could function to recruit host factor(s) controlling HIV-1 transcription to the ubiquitin-proteasome pathway.
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Affiliation(s)
- Sanae Shoji-Kawata
- Department of Virology, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
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