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Aryal M, Lin D, Regan K, Du S, Shi H, Alvarado JJ, Ilina TV, Andreotti AH, Smithgall TE. The HIV-1 protein Nef activates the Tec family kinase Btk by stabilizing an intermolecular SH3-SH2 domain interaction. Sci Signal 2022; 15:eabn8359. [PMID: 36126115 PMCID: PMC9830684 DOI: 10.1126/scisignal.abn8359] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The Nef protein produced by the viruses HIV-1 and SIV drives efficient viral replication partially by inducing constitutive activation of host cell tyrosine kinases, including members of the Src and Tec families. Here, we uncovered the mechanism by which both HIV-1 and SIV Nef enhanced the activity of the Tec family kinase Btk in vitro and in cells. A Nef mutant that could not bind to the SH3 domain of Src family kinases activated Btk to the same extent as did wild-type Nef, demonstrating that Nef activated Src and Tec family kinases by distinct mechanisms. The Btk SH3-SH2 region formed a homodimer requiring the CD loop in the SH2 domain, which was stabilized by the binding of Nef homodimers. Alanine substitution of Pro327 in the CD loop of the Btk SH2 domain destabilized SH3-SH2 dimers, abolished the interaction with Nef, and prevented activation by Nef in vitro. In cells, Nef stabilized and activated wild-type but not P327A Btk homodimers at the plasma membrane. These data reveal that the interaction with Nef stabilizes Btk dimers through the SH3-SH2 interface to promote kinase activity and show that the HIV-1 Nef protein evolved distinct mechanisms to activate Src and Tec family tyrosine kinases to enhance viral replication.
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Affiliation(s)
- Manish Aryal
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh PA, 15219 USA
| | - David Lin
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA, 50011 USA
| | - Kiera Regan
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh PA, 15219 USA
| | - Shoucheng Du
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh PA, 15219 USA
| | - Haibin Shi
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh PA, 15219 USA
| | - John J. Alvarado
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh PA, 15219 USA
| | - Tatiana V. Ilina
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh PA, 15260 USA
| | - Amy H. Andreotti
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA, 50011 USA
| | - Thomas E. Smithgall
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh PA, 15219 USA,To whom correspondence should be addressed: Thomas E. Smithgall, Ph.D., Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Bridgeside Point II, Suite 523, 450 Technology Drive, Pittsburgh, PA 15219, Tel. 412-648-8106, Fax 412-624-8997,
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2
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Biswas A, Zhou D, Fiches GN, Wu Z, Liu X, Ma Q, Zhao W, Zhu J, Santoso NG. Inhibition of polo-like kinase 1 (PLK1) facilitates reactivation of gamma-herpesviruses and their elimination. PLoS Pathog 2021; 17:e1009764. [PMID: 34297745 PMCID: PMC8336821 DOI: 10.1371/journal.ppat.1009764] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 08/04/2021] [Accepted: 06/29/2021] [Indexed: 01/06/2023] Open
Abstract
Both Kaposi's sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV) establish the persistent, life-long infection primarily at the latent status, and associate with certain types of tumors, such as B cell lymphomas, especially in immuno-compromised individuals including people living with HIV (PLWH). Lytic reactivation of these viruses can be employed to kill tumor cells harboring latently infected viral episomes through the viral cytopathic effects and the subsequent antiviral immune responses. In this study, we identified that polo-like kinase 1 (PLK1) is induced by KSHV de novo infection as well as lytic switch from KSHV latency. We further demonstrated that PLK1 depletion or inhibition facilitates KSHV reactivation and promotes cell death of KSHV-infected lymphoma cells. Mechanistically, PLK1 regulates Myc that is critical to both maintenance of KSHV latency and support of cell survival, and preferentially affects the level of H3K27me3 inactive mark both globally and at certain loci of KSHV viral episomes. Furthremore, we recognized that PLK1 inhibition synergizes with STAT3 inhibition to efficiently induce KSHV reactivation. We also confirmed that PLK1 depletion or inhibition yields the similar effect on EBV lytic reactivation and cell death of EBV-infected lymphoma cells. Lastly, we noticed that PLK1 in B cells is elevated in the context of HIV infection and caused by HIV Nef protein to favor KSHV/EBV latency.
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Affiliation(s)
- Ayan Biswas
- Department of Pathology, Ohio State University College of Medicine, Columbus, Ohio, United States of America
- Department of Genetics, School of Medicine, Unversity of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Dawei Zhou
- Department of Pathology, Ohio State University College of Medicine, Columbus, Ohio, United States of America
| | - Guillaume N. Fiches
- Department of Pathology, Ohio State University College of Medicine, Columbus, Ohio, United States of America
| | - Zhenyu Wu
- Department of Pathology, Ohio State University College of Medicine, Columbus, Ohio, United States of America
- Department of Biomedical Informatics, Ohio State University College of Medicine, Columbus, Ohio, United States of America
| | - Xuefeng Liu
- Department of Pathology, Ohio State University College of Medicine, Columbus, Ohio, United States of America
- Department of Pathology, Center for Cell Reprogramming, Georgetown University Medical Center, Washington, D.C., United States of America
| | - Qin Ma
- Department of Biomedical Informatics, Ohio State University College of Medicine, Columbus, Ohio, United States of America
| | - Weiqiang Zhao
- Department of Pathology, Ohio State University College of Medicine, Columbus, Ohio, United States of America
| | - Jian Zhu
- Department of Pathology, Ohio State University College of Medicine, Columbus, Ohio, United States of America
| | - Netty G. Santoso
- Department of Pathology, Ohio State University College of Medicine, Columbus, Ohio, United States of America
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3
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Synergy and allostery in ligand binding by HIV-1 Nef. Biochem J 2021; 478:1525-1545. [PMID: 33787846 PMCID: PMC8079166 DOI: 10.1042/bcj20201002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 03/29/2021] [Accepted: 03/31/2021] [Indexed: 11/27/2022]
Abstract
The Nef protein of human and simian immunodeficiency viruses boosts viral pathogenicity through its interactions with host cell proteins. By combining the polyvalency of its large unstructured regions with the binding selectivity and strength of its folded core domain, Nef can associate with many different host cell proteins, thereby disrupting their functions. For example, the combination of a linear proline-rich motif and hydrophobic core domain surface allows Nef to bind tightly and specifically to SH3 domains of Src family kinases. We investigated whether the interplay between Nef's flexible regions and its core domain could allosterically influence ligand selection. We found that the flexible regions can associate with the core domain in different ways, producing distinct conformational states that alter the way in which Nef selects for SH3 domains and exposes some of its binding motifs. The ensuing crosstalk between ligands might promote functionally coherent Nef-bound protein ensembles by synergizing certain subsets of ligands while excluding others. We also combined proteomic and bioinformatics analyses to identify human proteins that select SH3 domains in the same way as Nef. We found that only 3% of clones from a whole-human fetal library displayed Nef-like SH3 selectivity. However, in most cases, this selectivity appears to be achieved by a canonical linear interaction rather than by a Nef-like ‘tertiary' interaction. Our analysis supports the contention that Nef's mode of hijacking SH3 domains is a virus-specific adaptation with no or very few cellular counterparts. Thus, the Nef tertiary binding surface is a promising virus-specific drug target.
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Li WF, Aryal M, Shu ST, Smithgall TE. HIV-1 Nef dimers short-circuit immune receptor signaling by activating Tec-family kinases at the host cell membrane. J Biol Chem 2020; 295:5163-5174. [PMID: 32144207 DOI: 10.1074/jbc.ra120.012536] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 03/04/2020] [Indexed: 01/08/2023] Open
Abstract
The HIV-1 virulence factor Nef promotes high-titer viral replication, immune escape, and pathogenicity. Nef interacts with interleukin-2-inducible T-cell kinase (Itk) and Bruton's tyrosine kinase (Btk), two Tec-family kinases expressed in HIV-1 target cells (CD4 T cells and macrophages, respectively). Using a cell-based bimolecular fluorescence complementation assay, here we demonstrate that Nef recruits both Itk and Btk to the cell membrane and induces constitutive kinase activation in transfected 293T cells. Nef homodimerization-defective mutants retained their interaction with both kinases but failed to induce activation, supporting a role for Nef homodimer formation in the activation mechanism. HIV-1 infection up-regulates endogenous Itk activity in SupT1 T cells and donor-derived peripheral blood mononuclear cells. However, HIV-1 strains expressing Nef variants with mutations in the dimerization interface replicated poorly and were significantly attenuated in Itk activation. We conclude that direct activation of Itk and Btk by Nef at the membrane in HIV-infected cells may override normal immune receptor control of Tec-family kinase activity to enhance the viral life cycle.
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Affiliation(s)
- Wing Fai Li
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, Pennsylvania 15219
| | - Manish Aryal
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, Pennsylvania 15219
| | - Sherry T Shu
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, Pennsylvania 15219
| | - Thomas E Smithgall
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, Pennsylvania 15219
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5
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Raja R, Lata S, Trivedi S, Banerjea AC. Serum deprivation/starvation leads to reactivation of HIV-1 in latently infected monocytes via activating ERK/JNK pathway. Sci Rep 2018; 8:14496. [PMID: 30262819 PMCID: PMC6160481 DOI: 10.1038/s41598-018-32316-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 09/03/2018] [Indexed: 01/04/2023] Open
Abstract
Despite the high success rate, antiretroviral therapy does not cure the disease completely due to presence of latent viral reservoirs. Although several studies have addressed this issue earlier, the role of serum starvation/deprivation in HIV-1 latency has not been studied. So, we investigated the role of serum starvation in regulating HIV-1 latency. The impact of serum starvation on HIV-1 latency was assessed in latently infected monocytes U1 and T-cells J1.1. Serum starvation breaks HIV-1 latency in U1 cells. Under similar conditions, J1.1 cells failed to show reactivation of virus. We investigated the involvement of cell death pathway and autophagy during the serum starvation in viral reactivation. Inhibition of these pathways did not affect viral reactivation. Furthermore, other crucial factors like NF-κB, SP1 and AKT did not play any role in regulating viral latency. Here, we report that serum deprivation up-regulates ERK/JNK pathway. This leads to phosphorylation of c-Jun which plays an important role in viral reactivation. Treatment of cells with U0126, an ERK kinase inhibitor, potently inhibited viral replication. In summary, we show that serum starvation leads to reactivation of HIV-1 in latently infected monocytes through the ERK/JNK pathway.
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Affiliation(s)
- Rameez Raja
- Laboratory of Virology, National Institute of Immunology, New Delhi, India.,Lerner Research Institute, Cleveland Clinic, Ohio, USA
| | - Sneh Lata
- Laboratory of Virology, National Institute of Immunology, New Delhi, India
| | - Shubhendu Trivedi
- Laboratory of Virology, National Institute of Immunology, New Delhi, India
| | - Akhil C Banerjea
- Laboratory of Virology, National Institute of Immunology, New Delhi, India.
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Ospina Stella A, Turville S. All-Round Manipulation of the Actin Cytoskeleton by HIV. Viruses 2018; 10:v10020063. [PMID: 29401736 PMCID: PMC5850370 DOI: 10.3390/v10020063] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 01/24/2018] [Accepted: 01/29/2018] [Indexed: 12/21/2022] Open
Abstract
While significant progress has been made in terms of human immunodeficiency virus (HIV) therapy, treatment does not represent a cure and remains inaccessible to many people living with HIV. Continued mechanistic research into the viral life cycle and its intersection with many aspects of cellular biology are not only fundamental in the continued fight against HIV, but also provide many key observations of the workings of our immune system. Decades of HIV research have testified to the integral role of the actin cytoskeleton in both establishing and spreading the infection. Here, we review how the virus uses different strategies to manipulate cellular actin networks and increase the efficiency of various stages of its life cycle. While some HIV proteins seem able to bind to actin filaments directly, subversion of the cytoskeleton occurs indirectly by exploiting the power of actin regulatory proteins, which are corrupted at multiple levels. Furthermore, this manipulation is not restricted to a discrete class of proteins, but rather extends throughout all layers of the cytoskeleton. We discuss prominent examples of actin regulators that are exploited, neutralized or hijacked by the virus, and address how their coordinated deregulation can lead to changes in cellular behavior that promote viral spreading.
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Affiliation(s)
- Alberto Ospina Stella
- The Kirby Institute, University of New South Wales (UNSW), Sydney NSW 2052, Australia.
| | - Stuart Turville
- The Kirby Institute, University of New South Wales (UNSW), Sydney NSW 2052, Australia.
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7
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Nakhaeizadeh H, Amin E, Nakhaei-Rad S, Dvorsky R, Ahmadian MR. The RAS-Effector Interface: Isoform-Specific Differences in the Effector Binding Regions. PLoS One 2016; 11:e0167145. [PMID: 27936046 PMCID: PMC5147862 DOI: 10.1371/journal.pone.0167145] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 11/09/2016] [Indexed: 12/31/2022] Open
Abstract
RAS effectors specifically interact with the GTP-bound form of RAS in response to extracellular signals and link them to downstream signaling pathways. The molecular nature of effector interaction by RAS is well-studied but yet still incompletely understood in a comprehensive and systematic way. Here, structure-function relationships in the interaction between different RAS proteins and various effectors were investigated in detail by combining our in vitro data with in silico data. Equilibrium dissociation constants were determined for the binding of HRAS, KRAS, NRAS, RRAS1 and RRAS2 to both the RAS binding (RB) domain of CRAF and PI3Kα, and the RAS association (RA) domain of RASSF5, RALGDS and PLCε, respectively, using fluorescence polarization. An interaction matrix, constructed on the basis of available crystal structures, allowed identification of hotspots as critical determinants for RAS-effector interaction. New insights provided by this study are the dissection of the identified hotspots in five distinct regions (R1 to R5) in spite of high sequence variability not only between, but also within, RB/RA domain-containing effectors proteins. Finally, we propose that intermolecular β-sheet interaction in R1 is a central recognition region while R3 may determine specific contacts of RAS versus RRAS isoforms with effectors.
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Affiliation(s)
- Hossein Nakhaeizadeh
- Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich-Heine University, Düsseldorf, Germany
| | - Ehsan Amin
- Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich-Heine University, Düsseldorf, Germany
| | - Saeideh Nakhaei-Rad
- Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich-Heine University, Düsseldorf, Germany
| | - Radovan Dvorsky
- Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich-Heine University, Düsseldorf, Germany
| | - Mohammad Reza Ahmadian
- Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich-Heine University, Düsseldorf, Germany
- * E-mail:
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8
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Desai DV, Kulkarni SS. Herpes Simplex Virus: The Interplay Between HSV, Host, and HIV-1. Viral Immunol 2015; 28:546-55. [PMID: 26331265 DOI: 10.1089/vim.2015.0012] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Herpes simplex virus proteins interact with host (human) proteins and create an environment conducive for its replication. Genital ulceration due to herpes simplex virus type 2 (HSV-2) infections is an important clinical manifestation reported to increase the risk of human immunodeficiency virus type 1 (HIV-1) acquisition and replication in HIV-1/HSV-2 coinfection. Dampening the innate and adaptive immune responses of the skin-resident dendritic cells, HSV-2 not only helps itself, but creates a "yellow brick road" for one of the most dreaded viruses HIV, which is transmitted mainly through the sexual route. Although, data from clinical trials show that HSV-2 suppression reduces HIV-1 viral load, there are hardly any reports presenting conclusive evidence on the impact of HSV-2 coinfection on HIV-1 disease progression. Be that as it may, understanding the interplay between these three characters (HSV, host, and HIV-1) is imperative. This review endeavors to collate studies on the influence of HSV-derived proteins on the host response and HIV-1 replication. Studying such complex interactions may help in designing and developing common strategies for the two viruses to keep these "partners in crime" at bay.
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Affiliation(s)
- Dipen Vijay Desai
- Department of Virology, ICMR-National AIDS Research Institute , Pune, India
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9
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Liu X, Kumar A. Differential signaling mechanism for HIV-1 Nef-mediated production of IL-6 and IL-8 in human astrocytes. Sci Rep 2015; 5:9867. [PMID: 26075907 PMCID: PMC4467202 DOI: 10.1038/srep09867] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 03/05/2015] [Indexed: 01/01/2023] Open
Abstract
Variety of HIV-1 viral proteins including HIV-1 Nef are known to activate astrocytes and microglia in the brain and cause the release of pro-inflammatory cytokines, which is thought to be one of the mechanisms leading to HIV-1- mediated neurotoxicity. IL-6 and IL-8 have been found in the CSF of patients with HIV-1 associated dementia (HAD), suggesting that they might play important roles in HIV-1 neuropathology. In the present study we examined the effects of HIV-1 Nef on IL-6 and IL-8 induction in astrocytes. The results demonstrate that both IL-6 and IL-8 are significantly induced in HIV-1 Nef-transfected SVGA astrocytes and HIV-1 Nef-treated primary fetal astrocytes. We also determined the molecular mechanisms responsible for the HIV-1 Nef-induced increased IL-6 and IL-8 by using chemical inhibitors and siRNAs against PI3K/Akt/PKC, p38 MAPK, NF-κB, CEBP and AP-1. Our results clearly demonstrate that the PI3K/PKC, p38 MAPK, NF-κB and AP-1 pathways are involved in HIV-1 Nef-induced IL-6 production in astrocytes, while PI3K/PKC and NF-κB pathways are involved in HIV-1 Nef-induced IL-8 production. These results offer new potential targets to develop therapeutic strategy for treatment of HIV-1 associated neurological disorders, prevalent in > 40% of individuals infected with HIV-1.
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Affiliation(s)
- Xun Liu
- Division of Pharmacology and Toxicology, School of Pharmacy, University of Missouri, Kansas City, MO 64108
| | - Anil Kumar
- Division of Pharmacology and Toxicology, School of Pharmacy, University of Missouri, Kansas City, MO 64108
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Percario ZA, Ali M, Mangino G, Affabris E. Nef, the shuttling molecular adaptor of HIV, influences the cytokine network. Cytokine Growth Factor Rev 2014; 26:159-73. [PMID: 25529283 DOI: 10.1016/j.cytogfr.2014.11.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 11/05/2014] [Indexed: 12/17/2022]
Abstract
Several viruses manipulate host innate immune responses to avoid immune recognition and improve viral replication and spreading. The viral protein Nef of Human Immunodeficiency Virus is mainly involved in this "hijacking" activity and is a well established virulence factor. In the last few years there have been remarkable advances in outlining a defined framework of its functions. In particular Nef appears to be a shuttling molecular adaptor able to exert its effects both on infected and non infected bystander cell. In addition it is emerging fact that it has an important impact on the chemo-cytokine network. Nef protein represents an interesting new target to develop therapeutic drugs for treatment of seropositive patients. In this review we have tried to provide a unifying view of the multiple functions of this viral protein on the basis of recently available experimental data.
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Affiliation(s)
| | - Muhammad Ali
- Department of Sciences, University Roma Tre, Rome, Italy
| | - Giorgio Mangino
- Department of Medico-Surgical Sciences and Biotechnologies, Sapienza University of Rome, Italy
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Hillebrand F, Erkelenz S, Diehl N, Widera M, Noffke J, Avota E, Schneider-Schaulies S, Dabauvalle MC, Schaal H. The PI3K pathway acting on alternative HIV-1 pre-mRNA splicing. J Gen Virol 2014; 95:1809-1815. [DOI: 10.1099/vir.0.064618-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
HIV-1 mediates pro-survival signals and prevents apoptosis via the phosphatidylinositol-3-kinase (PI3K) pathway. This pathway, however, also affects phosphorylation of serine-arginine (SR) proteins, a family of splicing regulatory factors balancing splice site selection. We now show that pharmacologic inhibition of PI3K signalling alters the HIV-1 splicing pattern of both minigene- and provirus-derived mRNAs. This indicates that HIV-1 might also promote PI3K signalling to balance processing of its transcripts by regulating phosphorylation of splicing regulatory proteins.
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Affiliation(s)
- Frank Hillebrand
- Institute for Virology, Universitaetsklinikum Duesseldorf, Universitaetsstr. 1, D-40225 Duesseldorf, Germany
- Central Division for Electron Microscopy, University of Wuerzburg, Am Hubland, D-97074 Wuerzburg, Germany
| | - Steffen Erkelenz
- Institute for Virology, Universitaetsklinikum Duesseldorf, Universitaetsstr. 1, D-40225 Duesseldorf, Germany
| | - Nora Diehl
- Institute for Virology, Universitaetsklinikum Duesseldorf, Universitaetsstr. 1, D-40225 Duesseldorf, Germany
| | - Marek Widera
- Institute for Virology, Universitaetsklinikum Duesseldorf, Universitaetsstr. 1, D-40225 Duesseldorf, Germany
| | - Juliane Noffke
- Department of Dermatology, Universitaetsklinikum Duesseldorf, Moorenstrasse 5, D-40225 Duesseldorf, Germany
| | - Elita Avota
- Institute for Virology and Immunobiology, University of Wuerzburg, Versbacher Str. 7, D-97078 Wuerzburg, Germany
| | - Sibylle Schneider-Schaulies
- Institute for Virology and Immunobiology, University of Wuerzburg, Versbacher Str. 7, D-97078 Wuerzburg, Germany
| | - Marie-Christine Dabauvalle
- Central Division for Electron Microscopy, University of Wuerzburg, Am Hubland, D-97074 Wuerzburg, Germany
| | - Heiner Schaal
- Institute for Virology, Universitaetsklinikum Duesseldorf, Universitaetsstr. 1, D-40225 Duesseldorf, Germany
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HIV-1 Nef induces CCL5 production in astrocytes through p38-MAPK and PI3K/Akt pathway and utilizes NF-kB, CEBP and AP-1 transcription factors. Sci Rep 2014; 4:4450. [PMID: 24658403 PMCID: PMC3963078 DOI: 10.1038/srep04450] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 03/07/2014] [Indexed: 12/18/2022] Open
Abstract
The prevalence of HIV-associated neurocognitive disorders (HAND) remains high in patients infected with HIV-1. The production of pro-inflammatory cytokines by astrocytes/microglia exposed to viral proteins is thought to be one of the mechanisms leading to HIV-1- mediated neurotoxicity. In the present study we examined the effects of Nef on CCL5 induction in astrocytes. The results demonstrate that CCL5 is significantly induced in Nef-transfected SVGA astrocytes. To determine the mechanisms responsible for the increased CCL5 caused by Nef, we employed siRNA and chemical antagonists. Antagonists of NF-κB, PI3K, and p38 significantly reduced the expression levels of CCL5 induced by Nef transfection. Furthermore, specific siRNAs demonstrated that the Akt, p38MAPK, NF-κB, CEBP, and AP-1 pathways play a role in Nef-mediated CCL5 expression. The results demonstrated that the PI3K/Akt and p38 MAPK pathways, along with the transcription factors NF-κB, CEBP, and AP-1, are involved in Nef-induced CCL5 production in astrocytes.
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13
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Cool CD, Voelkel NF, Bull T. Viral infection and pulmonary hypertension: is there an association? Expert Rev Respir Med 2014; 5:207-16. [DOI: 10.1586/ers.11.17] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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14
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Zhu X, Guo Y, Yao S, Yan Q, Xue M, Hao T, Zhou F, Zhu J, Qin D, Lu C. Synergy between Kaposi's sarcoma-associated herpesvirus (KSHV) vIL-6 and HIV-1 Nef protein in promotion of angiogenesis and oncogenesis: role of the AKT signaling pathway. Oncogene 2013; 33:1986-96. [PMID: 23604117 DOI: 10.1038/onc.2013.136] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2012] [Revised: 02/04/2013] [Accepted: 02/28/2013] [Indexed: 12/16/2022]
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is the cause of Kaposi's sarcoma (KS), which is the most common AIDS-associated malignancy. KS is characterized by neovascularization and spindle cell proliferation. The interaction between HIV-1 and KSHV has a central role in promoting the aggressive manifestations of KS in AIDS patients; however, the pathogenesis underlying AIDS-related KS (AIDS-KS) remains unknown. Herein, we examined the potential of HIV-1 negative factor (Nef) to impact KSHV viral interleukin-6 (vIL-6)-induced angiogenesis and tumorigenesis. In vitro experiments showed that exogenous Nef penetrated vIL-6-expressing endothelial cells. Both internalized and ectopic expression of Nef in endothelial cells and fibroblasts synergized with vIL-6 to promote vascular tube formation and cell proliferation. Using a chicken chorioallantoic membrane (CAM) model, we demonstrated that Nef synergistically promotes vIL-6-induced angiogenesis and tumorigenesis. Animal experiments further showed that Nef facilitates vIL-6-induced angiogenesis and tumor formation in athymic nu/nu mice. Mechanistic studies indicated that Nef synergizes with vIL-6 to enhance angiogenesis and tumorigenesis by activating the AKT pathway in the CAM model, as well as nude mice. LY294002, a specific inhibitor of phosphatidylinositol-3-kinase (PI3K), significantly impaired the ability of Nef to promote vIL-6-induced tumorigenesis in an allograft model of nude mice. Our data provide first-line evidence that Nef may contribute to the pathogenesis underlying AIDS-KS in synergy with vIL-6. These novel findings also suggest that targeting the PI3K/AKT signal may be a potentially effective therapeutic approach in AIDS-KS patients.
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Affiliation(s)
- X Zhu
- 1] State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, PR China [2] Key Laboratory of Pathogen Biology of Jiangsu Province, Nanjing Medical University, Nanjing, PR China [3] Department of Microbiology and Immunology, Nanjing Medical University, Nanjing, PR China [4] Department of Laboratory Medicine, Jiangsu Province Hospital of Traditional Chinese Medicine, Nanjing, PR China
| | - Y Guo
- Department of Microbiology and Immunology, Nanjing Medical University, Nanjing, PR China
| | - S Yao
- Medical School, Quzhou College of Technology, Quzhou, PR China
| | - Q Yan
- Department of Microbiology and Immunology, Nanjing Medical University, Nanjing, PR China
| | - M Xue
- Department of Microbiology and Immunology, Nanjing Medical University, Nanjing, PR China
| | - T Hao
- Department of Microbiology and Immunology, Nanjing Medical University, Nanjing, PR China
| | - F Zhou
- Department of Microbiology and Immunology, Nanjing Medical University, Nanjing, PR China
| | - J Zhu
- Cancer Virology Program, University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA
| | - D Qin
- Department of Microbiology and Immunology, Nanjing Medical University, Nanjing, PR China
| | - C Lu
- 1] State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, PR China [2] Key Laboratory of Pathogen Biology of Jiangsu Province, Nanjing Medical University, Nanjing, PR China [3] Department of Microbiology and Immunology, Nanjing Medical University, Nanjing, PR China
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15
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Markle TJ, Philip M, Brockman MA. HIV-1 Nef and T-cell activation: a history of contradictions. Future Virol 2013; 8. [PMID: 24187576 DOI: 10.2217/fvl.13.20] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
HIV-1 Nef is a multifunctional viral protein that contributes to higher plasma viremia and more rapid disease progression. Nef appears to accomplish this, in part, through modulation of T-cell activation; however, the results of these studies over the past 25 years have been inconsistent. Here, the history of contradictory observations related to HIV-1 Nef and its ability to modulate T-cell activation is reviewed, and recent reports that may help to explain Net's apparent ability to both inhibit and activate T cells are highlighted.
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Affiliation(s)
- Tristan J Markle
- Simon Fraser University, 8888 University Drive, Burnaby BC V5A 1S6, Canada
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16
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El-Far M, Isabelle C, Chomont N, Bourbonnière M, Fonseca S, Ancuta P, Peretz Y, Chouikh Y, Halwani R, Schwartz O, Madrenas J, Freeman GJ, Routy JP, Haddad EK, Sékaly RP. Down-regulation of CTLA-4 by HIV-1 Nef protein. PLoS One 2013; 8:e54295. [PMID: 23372701 PMCID: PMC3553160 DOI: 10.1371/journal.pone.0054295] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2012] [Accepted: 12/10/2012] [Indexed: 11/19/2022] Open
Abstract
HIV-1 Nef protein down-regulates several cell surface receptors through its interference with the cell sorting and trafficking machinery. Here we demonstrate for the first time the ability of Nef to down-regulate cell surface expression of the negative immune modulator CTLA-4. Down-regulation of CTLA-4 required the Nef motifs DD175, EE155 and LL165, all known to be involved in vesicle trafficking. Disruption of the lysosomal functions by pH-neutralizing agents prevented CTLA-4 down-regulation by Nef, demonstrating the implication of the endosomal/lysosomal compartments in this process. Confocal microscopy experiments visualized the co-localization between Nef and CTLA-4 in the early and recycling endosomes but not at the cell surface. Overall, our results provide a novel mechanism by which HIV-1 Nef interferes with the surface expression of the negative regulator of T cell activation CTLA-4. Down-regulation of CTLA-4 may contribute to the mechanisms by which HIV-1 sustains T cell activation, a critical step in viral replication and dissemination.
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Affiliation(s)
- Mohamed El-Far
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Hôpital St-Luc, Montréal, Québec, Canada
- Laboratoire d'Immunologie, Département de Microbiologie et d'Immunologie, Université de Montréal, Montréal, Québec, Canada
| | - Catherine Isabelle
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Hôpital St-Luc, Montréal, Québec, Canada
- Laboratoire d'Immunologie, Département de Microbiologie et d'Immunologie, Université de Montréal, Montréal, Québec, Canada
| | - Nicolas Chomont
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Hôpital St-Luc, Montréal, Québec, Canada
- Laboratoire d'Immunologie, Département de Microbiologie et d'Immunologie, Université de Montréal, Montréal, Québec, Canada
- Vaccine and Gene Therapy Institute Florida, Port St. Lucie, Florida, United States of America
| | - Martin Bourbonnière
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Hôpital St-Luc, Montréal, Québec, Canada
- Laboratoire d'Immunologie, Département de Microbiologie et d'Immunologie, Université de Montréal, Montréal, Québec, Canada
| | - Simone Fonseca
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Hôpital St-Luc, Montréal, Québec, Canada
- Laboratoire d'Immunologie, Département de Microbiologie et d'Immunologie, Université de Montréal, Montréal, Québec, Canada
- Vaccine and Gene Therapy Institute Florida, Port St. Lucie, Florida, United States of America
| | - Petronela Ancuta
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Hôpital St-Luc, Montréal, Québec, Canada
| | - Yoav Peretz
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Hôpital St-Luc, Montréal, Québec, Canada
- Laboratoire d'Immunologie, Département de Microbiologie et d'Immunologie, Université de Montréal, Montréal, Québec, Canada
| | - Younes Chouikh
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Hôpital St-Luc, Montréal, Québec, Canada
- Laboratoire d'Immunologie, Département de Microbiologie et d'Immunologie, Université de Montréal, Montréal, Québec, Canada
| | - Rabih Halwani
- Prince Naif Center for Immunology Research and Department of Pediatrics, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Olivier Schwartz
- Virus and Immunity Group, Department of Virology, Institut Pasteur, Paris, France
| | - Joaquín Madrenas
- Department of Microbiology and Immunology, McGill University, Montreal, Canada
| | - Gordon J. Freeman
- Dana Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Jean-Pierre Routy
- Chronic Viral Illness Service and Division of Hematology, Royal Victoria Hospital, McGill University Health Centre, McGill University, Montréal, Canada
| | - Elias K. Haddad
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Hôpital St-Luc, Montréal, Québec, Canada
- Laboratoire d'Immunologie, Département de Microbiologie et d'Immunologie, Université de Montréal, Montréal, Québec, Canada
- Vaccine and Gene Therapy Institute Florida, Port St. Lucie, Florida, United States of America
| | - Rafick-Pierre Sékaly
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Hôpital St-Luc, Montréal, Québec, Canada
- Laboratoire d'Immunologie, Département de Microbiologie et d'Immunologie, Université de Montréal, Montréal, Québec, Canada
- Vaccine and Gene Therapy Institute Florida, Port St. Lucie, Florida, United States of America
- * E-mail:
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17
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Mukerji J, Olivieri KC, Misra V, Agopian KA, Gabuzda D. Proteomic analysis of HIV-1 Nef cellular binding partners reveals a role for exocyst complex proteins in mediating enhancement of intercellular nanotube formation. Retrovirology 2012; 9:33. [PMID: 22534017 PMCID: PMC3382630 DOI: 10.1186/1742-4690-9-33] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Accepted: 04/25/2012] [Indexed: 12/16/2022] Open
Abstract
Background HIV-1 Nef protein contributes to pathogenesis via multiple functions that include enhancement of viral replication and infectivity, alteration of intracellular trafficking, and modulation of cellular signaling pathways. Nef stimulates formation of tunneling nanotubes and virological synapses, and is transferred to bystander cells via these intercellular contacts and secreted microvesicles. Nef associates with and activates Pak2, a kinase that regulates T-cell signaling and actin cytoskeleton dynamics, but how Nef promotes nanotube formation is unknown. Results To identify Nef binding partners involved in Pak2-association dependent Nef functions, we employed tandem mass spectrometry analysis of Nef immunocomplexes from Jurkat cells expressing wild-type Nef or Nef mutants defective for the ability to associate with Pak2 (F85L, F89H, H191F and A72P, A75P in NL4-3). We report that wild-type, but not mutant Nef, was associated with 5 components of the exocyst complex (EXOC1, EXOC2, EXOC3, EXOC4, and EXOC6), an octameric complex that tethers vesicles at the plasma membrane, regulates polarized exocytosis, and recruits membranes and proteins required for nanotube formation. Additionally, Pak2 kinase was associated exclusively with wild-type Nef. Association of EXOC1, EXOC2, EXOC3, and EXOC4 with wild-type, but not mutant Nef, was verified by co-immunoprecipitation assays in Jurkat cells. Furthermore, shRNA-mediated depletion of EXOC2 in Jurkat cells abrogated Nef-mediated enhancement of nanotube formation. Using bioinformatic tools, we visualized protein interaction networks that reveal functional linkages between Nef, the exocyst complex, and the cellular endocytic and exocytic trafficking machinery. Conclusions Exocyst complex proteins are likely a key effector of Nef-mediated enhancement of nanotube formation, and possibly microvesicle secretion. Linkages revealed between Nef and the exocyst complex suggest a new paradigm of exocyst involvement in polarized targeting for intercellular transfer of viral proteins and viruses.
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Affiliation(s)
- Joya Mukerji
- Department of Cancer Immunology and AIDS, Dana Farber Cancer Institute, Boston, MA, USA
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18
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Suppiah S, Mousa HA, Tzeng WP, Matthews JD, Frey TK. Binding of cellular p32 protein to the rubella virus P150 replicase protein via PxxPxR motifs. J Gen Virol 2012; 93:807-816. [PMID: 22238231 DOI: 10.1099/vir.0.038901-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
A proline-rich region (PRR) within the rubella virus (RUBV) P150 replicase protein that contains three SH3 domain-binding motifs (PxxPxR) was investigated for its ability to bind cell proteins. Pull-down experiments using a glutathione S-transferase-PRR fusion revealed PxxPxR motif-specific binding with human p32 protein (gC1qR), which could be mediated by either of the first two motifs. This finding was of interest because p32 protein also binds to the RUBV capsid protein. Binding of p32 to P150 was confirmed and was abolished by mutation of the first two motifs. When mutations in the first two motifs were introduced into a RUBV cDNA infectious clone, virus replication was significantly impaired. However, virus RNA synthesis was found to be unaffected, and subsequent immunofluorescence analysis of RUBV-infected cells revealed co-localization of p32 and P150 but little overlap of p32 with RNA replication complexes, indicating that p32 does not participate directly in virus RNA synthesis. Thus, the role of p32 in RUBV replication remains unresolved.
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Affiliation(s)
- Suganthi Suppiah
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA
| | - Heather A Mousa
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA
| | - Wen-Pin Tzeng
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA
| | - Jason D Matthews
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA
| | - Teryl K Frey
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA
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19
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Chan PM, Manser E. PAKs in Human Disease. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 106:171-87. [DOI: 10.1016/b978-0-12-396456-4.00011-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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20
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Neospora caninum: comparative gene expression profiling of Neospora caninum wild type and a temperature sensitive clone. Exp Parasitol 2011; 129:346-54. [PMID: 21963790 DOI: 10.1016/j.exppara.2011.09.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 09/13/2011] [Accepted: 09/16/2011] [Indexed: 11/21/2022]
Abstract
To understand the genetic basis of virulence, gene expression profiles of a temperature-sensitive clone (NCts-8, relatively avirulent) and its wild type (NC-1) of Neospora caninum were characterized and compared using a high-density microarray with approximately 63,000 distinct oligonucleotides. This microarray consists of 5692 unique N. caninum sequences, including 1980 Tentative Consensus sequences and 3712 singleton ESTs from the TIGR N. caninum Gene Index (NCGI, release 5.0). Each sequence was represented by 11 distinct 60mer oligonucleotides synthesized in situ on the microarray. The results showed that 111 genes were significantly repressed and no up-regulated genes were identified in the NCts-8 clone. The level of 10 randomly selected genes from the repressed genes was confirmed using real-time RT-PCR. Of the 111 repressed genes, 58 were hypothetical protein products and 53 were annotated genes. Over 70% of the repressed genes identified in this study are clustered on five chromosomes (I, VII, VIII, X and XII). These results suggest that the down-regulated genes may be in part responsible for the reduced pathogenesis of NCts-8; further characterization of the regulated genes may aid in understanding of molecular basis of virulence and development of countermeasures against neosporosis.
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21
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Herpes simplex virus requires VP11/12 to activate Src family kinase-phosphoinositide 3-kinase-Akt signaling. J Virol 2011; 85:2803-12. [PMID: 21228233 DOI: 10.1128/jvi.01877-10] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
We previously showed that the herpes simplex virus 1 (HSV-1) tegument protein VP11/12 activates the lymphocyte-specific Src family kinase (SFK) Lck and is tyrosine phosphorylated in an Lck-dependent manner during T cell infection. We now extend these findings to show that ectopic expression of Lck induces robust tyrosine phosphorylation of VP11/12 in Vero cells, strongly suggesting that VP11/12 participates in an Lck-mediated signaling pathway as a substrate of Lck or a kinase activated by Lck. We sought to elucidate signaling events downstream of VP11/12-SFK interactions. SFKs lie upstream of the canonical phosphoinositide 3-kinase (PI3K)-Akt pathway in signaling emanating from immune receptors, growth factor receptors, and polyomavirus middle T antigen. Here, we show that VP11/12 is required for virus-induced activation of PI3K-Akt signaling in HSV-infected Jurkat T cells and primary fibroblasts. VP11/12 interacts with PI3K or PI3K signaling complexes during infection, suggesting that VP11/12 activates PI3K directly. SFK activity is required for tyrosine phosphorylation of VP11/12, VP11/12-PI3K interactions, and Akt activation in infected fibroblasts, suggesting that SFK-dependent phosphorylation of VP11/12 is required for interactions with downstream signaling effectors. Akt controls many biological functions, including cell survival, cell motility, and translation, but it is currently unclear which Akt targets are modulated by VP11/12 during infection. Although the Akt target mTORC1 is activated during HSV-1 infection, VP11/12 is not required for this effect, implying that one or more additional viral proteins regulate this pathway. Further studies are therefore required to determine which Akt targets and associated biological functions are uniquely modulated by VP11/12.
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22
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Bergonzini V, Calistri A, Salata C, Del Vecchio C, Sartori E, Parolin C, Palù G. Nef and cell signaling transduction: a possible involvement in the pathogenesis of human immunodeficiency virus-associated dementia. J Neurovirol 2010; 15:238-48. [PMID: 19455469 DOI: 10.1080/13550280902939748] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Although the introduction of highly active antiretroviral therapy (HAART) has resulted in a significant decrease of acquired immunodeficiency syndrome (AIDS) morbidity and mortality, the prevalence of human immunodeficiency virus (HIV)-associated dementia (HAD) has actually risen, due to the increasing life expectancy of the infected subjects. To date, several aspects of the HAD pathogenesis remain to be dissected. In particular, the viral-cellular protein interplay is still under investigation. Given their specific features, two viral proteins, Tat and Nef, have been mainly hypothesized to play a role in HIV neuropathology. Here we show that HIV-1 Nef has an effect on the transcriptional levels of a cellular protein, anaplastic lymphoma kinase (ALK), that is preferentially expressed in the central and peripheral nervous system at late embryonic stages. By its overexpression along with Nef, the authors demonstrate ALK ability to influence, at least in the U87MG astrocytic glioma cells, the mytogen-activated protein kinase (MAP-K)-dependent pathway. Moreover, although in the absence of a physical direct interaction, Nef and ALK activate matrix metalloproteinases (MMPs), which are likely to contribute to blood-brain barrier (BBB) damage in HAD. Finally, in the in vitro model of glioblastoma cells adopted, Nef and ALK show similar effects by increasing different cytochines/chemokines that may be relevant for HAD pathogenesis. If confirmed in vivo, these data may indicate that, thanks to its ability to interfere with specific cellular pathways involved in BBB damage and in central nervous system (CNS) integrity, Nef, along with specific cellular counterparts, could be one of the viral players implicated in HAD development.
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Affiliation(s)
- Valeria Bergonzini
- Department of Histology, Microbiology, and Medical Biotechnologies, Division of Microbiology and Virology, University of Padova, Padova, Italy
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23
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Abstract
Pulmonary arterial hypertension (PAH) remains a vexing clinical disease with no cure. Despite advances and the discovery of a gene (BMPR2) associated with many of the hereditary forms of the disease, and some cases not previously known to be inherited, the reasons for mutations in this gene as a cause remain somewhat elusive. Clearly, a complex interplay exists between genetic alterations, environmental exposures (including infections), and disease development. This article addresses the advances in the genetics of PAH, including the identification of genetic etiologies and modulators, and the role of genetics in predicting disease progression and targeting therapeutics.
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24
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Van den Broeke C, Radu M, Chernoff J, Favoreel HW. An emerging role for p21-activated kinases (Paks) in viral infections. Trends Cell Biol 2010; 20:160-9. [PMID: 20071173 DOI: 10.1016/j.tcb.2009.12.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2009] [Revised: 12/14/2009] [Accepted: 12/14/2009] [Indexed: 01/28/2023]
Abstract
p21-activated protein kinases (Paks) are cytosolic serine/threonine protein kinases that act as effectors for small (p21) GTPases of the Cdc42 and Rac families. It has long been established that Paks play a major role in a host of vital cellular functions such as proliferation, survival and motility, and abnormal Pak function is associated with a number of human diseases. Here, we discuss emerging evidence that these enzymes also play a major role in the entry, replication and spread of many important pathogenic human viruses, including HIV. Careful assessment of the potential role of Paks in antiviral immunity will be pivotal to evaluate thoroughly the potential of agents that inhibit Pak as a new class of anti-viral therapeutics.
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Affiliation(s)
- Celine Van den Broeke
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
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25
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Feng X, Lu TC, Chuang PY, Fang W, Ratnam K, Xiong H, Ouyang X, Shen Y, Levy DE, Hyink D, Klotman M, D'Agati V, Iyengar R, Klotman PE, He JC. Reduction of Stat3 activity attenuates HIV-induced kidney injury. J Am Soc Nephrol 2009; 20:2138-46. [PMID: 19608706 PMCID: PMC2754106 DOI: 10.1681/asn.2008080879] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2008] [Accepted: 05/15/2009] [Indexed: 11/03/2022] Open
Abstract
HIV-1 Nef induces podocyte proliferation and dedifferentiation by activating the Stat3 and MAPK1,2 pathways. Activation of Stat3 also occurs in human kidneys affected by HIV-associated nephropathy (HIVAN), but its contribution to the development of HIVAN is unknown. Here, we generated HIV-1 transgenic mice (Tg26) with either 75% Stat3 activity (Tg26-SA/+) or 25% Stat3 activity (Tg26-SA/-). The kidneys of Tg26-SA/+ mice, but not Tg26-SA/- mice, showed increased Stat3 phosphorylation. The Tg26-SA/+ phenotype was not different from Tg26 mice, but Tg26-SA/- mice developed significantly less proteinuria, glomerulosclerosis, and tubulointerstitial injury. Tg26-SA/+ mice exhibited reduced expression of podocyte differentiation markers and increased expression of VEGF and proliferation markers as compared to Tg26-SA/- mice. Primary podocytes isolated from Tg26-SA/+ mice showed increased Stat3 phosphorylation and reduced expression of podocyte differentiation markers. The tubulointerstitial compartment and isolated tubules of Tg26-SA/+ mice also had increased Stat3 phosphorylation and expression of Stat3 target genes. We confirmed that the expression of the HIV-1 transgene and reduction of Stat3 activity did not affect T and B cell development. In conclusion, Stat3 plays a critical role in the pathogenesis of HIVAN.
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Affiliation(s)
- Xiaobei Feng
- Department of Nephrology, RuiJin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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26
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Pacheco A, Chernoff J. Group I p21-activated kinases: emerging roles in immune function and viral pathogenesis. Int J Biochem Cell Biol 2009; 42:13-6. [PMID: 19747561 DOI: 10.1016/j.biocel.2009.09.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2009] [Revised: 09/02/2009] [Accepted: 09/03/2009] [Indexed: 01/18/2023]
Abstract
Group I p21-activated kinases are a highly conserved three-member family of serine/threonine kinases that act as key effectors for the small GTPases Cdc42 and Rac. In man, these enzymes have been implicated in a wide range of biological processes and are beginning to draw the attention of the pharmaceutical industry as potential therapeutic targets in cancer and in inflammatory processes. In this review, we summarize basic properties of group I Paks and discuss recently uncovered roles for these kinases in immune function and in viral infection.
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27
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Olivetta E, Mallozzi C, Ruggieri V, Pietraforte D, Federico M, Sanchez M. HIV-1 Nef induces p47(phox) phosphorylation leading to a rapid superoxide anion release from the U937 human monoblastic cell line. J Cell Biochem 2009; 106:812-22. [PMID: 19130504 DOI: 10.1002/jcb.22041] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The Nef protein of the human immunodeficiency virus type 1 (HIV-1) plays a crucial role in AIDS pathogenesis by modifying host cell signaling pathways. We investigated the effects of Nef on the NADPH oxidase complex, a key enzyme involved in the generation of reactive oxygen species during the respiratory burst in human monocyte/macrophages. We have recently shown that the inducible expression of HIV-1 Nef in human macrophages cell line modulates in bi-phasic mode the superoxide anion release by NADPH oxidase, inducing a fast increase of the superoxide production, followed by a delayed strong inhibition mediated by Nef-induced soluble factor(s). Our study is focused on the molecular mechanisms involved in Nef-mediated activation of NADPH oxidase and superoxide anion release. Using U937 cells stably transfected with different Nef alleles, we found that both Nef membrane localization and intact SH3-binding domain are needed to induce superoxide release. The lack of effect during treatment with a specific MAPK pathway inhibitor, PD98059, demonstrated that Nef-induced superoxide release is independent of Erk1/2 phosphorylation. Furthermore, Nef induced the phosphorylation and then the translocation of the cytosolic subunit of NADPH oxidase complex p47(phox) to the plasma membrane. Adding the inhibitor PP2 prevented this process, evidencing the involvement of the Src family kinases on Nef-mediated NADPH oxidase activation. In addition, LY294002, a specific inhibitor of phosphoinositide 3-kinase (PI3K) inhibited both the Nef-induced p47(phox) phosphorylation and the superoxide anion release. These data indicate that Nef regulates the NADPH oxidase activity through the activation of the Src kinases and PI3K.
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Affiliation(s)
- Eleonora Olivetta
- National AIDS Centre, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Roma, Italy
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28
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Activation of the PI3K/Akt pathway early during vaccinia and cowpox virus infections is required for both host survival and viral replication. J Virol 2009; 83:6883-99. [PMID: 19386722 DOI: 10.1128/jvi.00245-09] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Viral manipulation of the transduction pathways associated with key cellular functions such as actin remodeling, microtubule stabilization, and survival may favor a productive viral infection. Here we show that consistent with the vaccinia virus (VACV) and cowpox virus (CPXV) requirement for cytoskeleton alterations early during the infection cycle, PBK/Akt was phosphorylated at S473 [Akt(S473-P)], a modification associated with the mammalian target of rapamycin complex 2 (mTORC2), which was paralleled by phosphorylation at T308 [Akt(T308-P)] by PI3K/PDK1, which is required for host survival. Notably, while VACV stimulated Akt(S473-P/T308-P) at early (1 h postinfection [p.i.]) and late (24 h p.i.) times during the infective cycle, CPXV stimulated Akt at early times only. Pharmacological and genetic inhibition of PI3K (LY294002) or Akt (Akt-X and a dominant-negative form of Akt-K179M) resulted in a significant decline in virus yield (from 80% to >/=90%). This decline was secondary to the inhibition of late viral gene expression, which in turn led to an arrest of virion morphogenesis at the immature-virion stage of the viral growth cycle. Furthermore, the cleavage of both caspase-3 and poly(ADP-ribose) polymerase and terminal deoxynucleotidyl transferase-mediated deoxyuridine nick end labeling assays confirmed that permissive, spontaneously immortalized cells such as A31 cells and mouse embryonic fibroblasts (MEFs) underwent apoptosis upon orthopoxvirus infection plus LY294002 treatment. Thus, in A31 cells and MEFs, early viral receptor-mediated signals transmitted via the PI3K/Akt pathway are required and precede the expression of viral antiapoptotic genes. Additionally, the inhibition of these signals resulted in the apoptosis of the infected cells and a significant decline in viral titers.
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29
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Arhel NJ, Kirchhoff F. Implications of Nef: host cell interactions in viral persistence and progression to AIDS. Curr Top Microbiol Immunol 2009; 339:147-75. [PMID: 20012528 DOI: 10.1007/978-3-642-02175-6_8] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The HIV and SIV Nef accessory proteins are potent enhancers of viral persistence and accelerate progression to AIDS in HIV-1-infected patients and non-human primate models. Although relatively small (27-35 kD), Nef can interact with a multitude of cellular factors and induce complex changes in trafficking, signal transduction, and gene expression that together converge to promote viral replication and immune evasion. In particular, Nef recruits several immunologically relevant cellular receptors to the endocytic machinery to reduce the recognition and elimination of virally infected cells by the host immune system, while simultaneously interacting with various kinases to promote T cell activation and viral replication. This review provides an overview on selected Nef interactions with host cell proteins, and discusses their possible relevance for viral spread and pathogenicity.
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Affiliation(s)
- Nathalie J Arhel
- Institute of Virology, Universitätsklinikum Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany
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Tachado SD, Li X, Swan K, Patel N, Koziel H. Constitutive activation of phosphatidylinositol 3-kinase signaling pathway down-regulates TLR4-mediated tumor necrosis factor-alpha release in alveolar macrophages from asymptomatic HIV-positive persons in vitro. J Biol Chem 2008; 283:33191-8. [PMID: 18826950 DOI: 10.1074/jbc.m805067200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Alveolar macrophages represent critical effector cells of innate immunity to infectious challenge in the lungs and recognize bacterial pathogens through pattern recognition receptors such as Toll-like receptors (TLRs). Phosphatidylinositol 3-kinase (PI3K) regulates TLR-mediated cytokine release, but whether HIV infection influences PI3K signaling pathway and alters TLR4-mediated macrophage response has not been investigated. In the current study, surface TLR4 expression were similar but TLR4 activation (lipid A, 10 microg/ml) resulted in lower TNF-alpha release by HIV+ human macrophages compared with healthy cells. Pharmacological inhibition of PI3K (LY294002) normalized TNF-alpha release in HIV+ macrophages and augments ERK1/2 mitogen-activated protein kinase phosphorylation in response to lipid A. Importantly, HIV+ macrophages demonstrated increased constitutive phosphatidylinositol 3,4,5-trisphosphate formation, increased phosphorylation of downstream signaling molecules Akt and glycogen synthase kinase-3beta (GSK-3beta) at Ser9, and reduced PTEN protein expression. As a functional assessment of GSK-3beta phosphorylation, TLR4-mediated interleukin-10 release was significantly higher in HIV+ human macrophages compared with healthy cells. Incubation of human macrophages with exogenous HIV Nef protein induced phosphorylation of Akt and GSK-3beta (whereas phosphorylation was reduced by PI3K inhibition) and promoted interleukin-10 release. Taken together, these data demonstrate increased constitutive activation of the PI3K signaling pathway in HIV+ macrophages and support the concept that PI3K activation (by HIV proteins such as Nef) may contribute to reduced TLR4-mediated TNF-alpha release in HIV+ human macrophages and impair host cell response to infectious challenge.
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Affiliation(s)
- Souvenir D Tachado
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA.
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Proteomic studies reveal coordinated changes in T-cell expression patterns upon infection with human immunodeficiency virus type 1. J Virol 2008; 82:4320-30. [PMID: 18287243 DOI: 10.1128/jvi.01819-07] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
We performed an extensive two-dimensional differential in-gel electrophoresis proteomic analysis of the cellular changes in human T cells upon human immunodeficiency virus type 1 (HIV-1) infection. We detected 2,000 protein spots, 15% of which were differentially expressed at peak infection. A total of 93 proteins that changed in relative abundance were identified. Of these, 27 were found to be significantly downregulated and 66 were upregulated at peak HIV infection. Early in infection, only a small group of proteins was changed. A clear and consistent program of metabolic rerouting could be seen, in which glycolysis was downregulated and mitochondrial oxidation enhanced. Proteins that participate in apoptotic signaling were also significantly influenced. Apart from these changes, the virus also strongly influenced levels of proteins involved in intracellular transport. These and other results are discussed in light of previous microarray and proteomic studies regarding the impact of HIV-1 infection on cellular mRNA and protein content.
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Hung CH, Thomas L, Ruby CE, Atkins KM, Morris NP, Knight ZA, Scholz I, Barklis E, Weinberg AD, Shokat KM, Thomas G. HIV-1 Nef assembles a Src family kinase-ZAP-70/Syk-PI3K cascade to downregulate cell-surface MHC-I. Cell Host Microbe 2007; 1:121-33. [PMID: 18005690 DOI: 10.1016/j.chom.2007.03.004] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Revised: 01/25/2007] [Accepted: 03/20/2007] [Indexed: 11/24/2022]
Abstract
HIV-1 Nef, which is required for the efficient onset of AIDS, enhances viral replication and infectivity by exerting multiple effects on infected cells. Nef downregulates cell-surface MHC-I molecules by an uncharacterized PI3K pathway requiring the actions of two Nef motifs-EEEE(65) and PXXP(75). We report that the Nef EEEE(65) targeting motif enables Nef PXXP(75) to bind and activate a trans-Golgi network-localized Src family tyrosine kinase (SFK). The Nef/SFK complex then recruits and phosphorylates the tyrosine kinase ZAP-70, which binds class I PI3K to trigger MHC-I downregulation in primary CD4+ T cells. In promonocytic cells, Nef/SFK recruits the ZAP-70 homolog Syk to downregulate MHC-I, implicating this PI3K pathway in multiple HIV-1 reservoirs. Isoform-specific PI3K inhibitors repress MHC-I downregulation, identifying them as potential therapeutic agents to combat HIV-1. The discovery of this Nef-SFK-ZAP-70/Syk-PI3K signaling pathway explains the hierarchal role of the Nef motifs in effecting immunoevasion.
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Affiliation(s)
- Chien-Hui Hung
- Vollum Institute, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239, USA
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Hale BG, Batty IH, Downes CP, Randall RE. Binding of influenza A virus NS1 protein to the inter-SH2 domain of p85 suggests a novel mechanism for phosphoinositide 3-kinase activation. J Biol Chem 2007; 283:1372-1380. [PMID: 18029356 DOI: 10.1074/jbc.m708862200] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Influenza A virus NS1 protein stimulates host-cell phosphoinositide 3-kinase (PI3K) signaling by binding to the p85beta regulatory subunit of PI3K. Here, in an attempt to establish a mechanism for this activation, we report further on the functional interaction between NS1 and p85beta. Complex formation was found to be independent of NS1 RNA binding activity and is mediated by the C-terminal effector domain of NS1. Intriguingly, the primary direct binding site for NS1 on p85beta is the inter-SH2 domain, a coiled-coil structure that acts as a scaffold for the p110 catalytic subunit of PI3K. In vitro kinase activity assays, together with protein binding competition studies, reveal that NS1 does not displace p110 from the inter-SH2 domain, and indicate that NS1 can form an active heterotrimeric complex with PI3K. In addition, it was established that residues at the C terminus of the inter-SH2 domain are essential for mediating the interaction between p85beta and NS1. Equivalent residues in p85alpha have previously been implicated in the basal inhibition of p110. However, such p85alpha residues were unable to substitute for those in p85beta with regards NS1 binding. Overall, these data suggest a model by which NS1 activates PI3K catalytic activity by masking a normal regulatory element specific to the p85beta inter-SH2 domain.
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Affiliation(s)
- Benjamin G Hale
- Centre for Biomolecular Sciences, University of St. Andrews, St. Andrews, Fife KY16 9ST, United Kingdom.
| | - Ian H Batty
- Division of Molecular Physiology, Faculty of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - C Peter Downes
- Division of Molecular Physiology, Faculty of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Richard E Randall
- Centre for Biomolecular Sciences, University of St. Andrews, St. Andrews, Fife KY16 9ST, United Kingdom
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Schindler M, Rajan D, Specht A, Ritter C, Pulkkinen K, Saksela K, Kirchhoff F. Association of Nef with p21-activated kinase 2 is dispensable for efficient human immunodeficiency virus type 1 replication and cytopathicity in ex vivo-infected human lymphoid tissue. J Virol 2007; 81:13005-14. [PMID: 17881449 PMCID: PMC2169106 DOI: 10.1128/jvi.01436-07] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Interaction of the human immunodeficiency virus type 1 (HIV-1) Nef protein with p21-activated kinase 2 (PAK2) has been proposed to play a role in T-cell activation, viral replication, apoptosis, and progression to AIDS. However, these hypotheses were based on results obtained using Nef mutants impaired in multiple functions. Recently, it was reported that Nef residue F191 is specifically involved in PAK2 binding. However, only a limited number of Nef activities were investigated in these studies. To further evaluate the role of F191 in Nef function and to elucidate the biological relevance of Nef-PAK2 interaction, we performed a comprehensive analysis of HIV-1 Nef mutants carrying F191H and F191R mutations. We found that the F191H mutation reduces and the F191R mutation disrupts the association of Nef with PAK2. Both mutants upregulated the major histocompatibility complex II (MHC-II)-associated invariant chain and downregulated CD4, MHC-I, and CD28, although with reduced efficiency for the latter. Furthermore, the F191H/R changes neither affected the levels of interleukin-2 receptor expression and apoptosis of HIV-1-infected primary T cells nor reduced Nef-mediated induction of NFAT. Unexpectedly, the F191H change markedly reduced and the F191R mutation disrupted the ability of Nef to enhance virion infectivity in P4-CCR5 indicator cells but not in TZM-bl cells or peripheral blood mononuclear cells. Most importantly, all HIV-1 Nef mutants replicated efficiently and caused CD4+ T-cell depletion in ex vivo-infected human lymphoid tissue. Altogether, our data show that the interaction of Nef with PAK2 does not play a major role in T-cell activation, viral replication, and apoptosis.
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Abstract
The secondary role of pathology in the present clinical management of pulmonary hypertension (PH) reflects to some extent the limitations of the current understanding of the disease. Ample room exists for the diagnostic translation of the pathobiologic studies, with the goal of improving the diagnostic and prognostic power of the pathologic assessment of pulmonary vascular remodeling. This article seeks to show the complementarities of the pathology and pathobiology of PH.
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Affiliation(s)
- Rubin M Tuder
- Division of Cardiopulmonary Pathology, Johns Hopkins University School of Medicine, 720 Rutland Avenue, Ross Research Building, Baltimore, MD 21217, USA.
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Kim MO, Suh HS, Si Q, Terman BI, Lee SC. Anti-CD45RO suppresses human immunodeficiency virus type 1 replication in microglia: role of Hck tyrosine kinase and implications for AIDS dementia. J Virol 2007; 80:62-72. [PMID: 16352531 PMCID: PMC1317521 DOI: 10.1128/jvi.80.1.62-72.2006] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Macrophages and microglia are productively infected by HIV-1 and play a pivotal role in the pathogenesis of AIDS dementia. Although macrophages and microglia express CD45, a transmembrane protein tyrosine phosphatase, whether modulation of its activity affects human immunodeficiency virus type 1 (HIV-1) replication is unknown. Here, we report that of the five human CD45 isoforms, microglia express CD45RB and CD45RO (RB > RO) and treatment of microglia with a CD45 agonist antibody alphaCD45RO (UCHL-1) inhibits HIV-1 replication. alphaCD45RO prevented HIV-1 negative factor (Nef)-induced autophosphorylation of hematopoietic cell kinase (Hck), a myeloid lineage-specific Src kinase. Recombinant CD45 protein also inhibited HIV-1-induced Hck phosphorylation in microglia. Antennapedia-mediated delivery of Hck Src homology domain 3 (SH3), a domain that binds to the Nef PxxP motif with high affinity, reduced HIV-1-induced Hck phosphorylation and HIV-1 production in microglia. HIV-1-induced LTR transactivation was observed in U38 cells stably overexpressing wild-type Hck but not kinase-inactive Hck. In microglia, alphaCD45RO reduced activation of transcription factors (NF-kappaB and CCAAT enhancer binding protein) necessary for LTR transactivation in macrophages. These results establish that in myeloid lineage cells, Nef interacts with the Hck SH3 domain, resulting in autophosphorylation of Hck and an increase in HIV-1 transcription. alphaCD45RO-mediated inhibition of HIV-1 replication in microglia identifies the CD45 protein tyrosine phosphatase as a potential therapeutic target for HIV-1 infection/AIDS dementia.
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Affiliation(s)
- Mee-Ohk Kim
- Department of Pathology, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461, USA
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38
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Foster JL, Garcia JV. Role of Nef in HIV-1 replication and pathogenesis. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2007; 55:389-409. [PMID: 17586321 DOI: 10.1016/s1054-3589(07)55011-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- John L Foster
- Department of Internal Medicine, University of Texas Southwestern, Medical Center, Dallas, TX 75390, USA
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Costa LJ, Chen N, Lopes A, Aguiar RS, Tanuri A, Plemenitas A, Peterlin BM. Interactions between Nef and AIP1 proliferate multivesicular bodies and facilitate egress of HIV-1. Retrovirology 2006; 3:33. [PMID: 16764724 PMCID: PMC1526754 DOI: 10.1186/1742-4690-3-33] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2006] [Accepted: 06/09/2006] [Indexed: 12/13/2022] Open
Abstract
Background Nef is an accessory protein of primate lentiviruses, HIV-1, HIV-2 and SIV. Besides removing CD4 and MHC class I from the surface and activating cellular signaling cascades, Nef also binds GagPol during late stages of the viral replicative cycle. In this report, we investigated further the ability of Nef to facilitate the replication of HIV-1. Results To this end, first the release of new viral particles was much lower in the absence of Nef in a T cell line. Since the same results were obtained in the absence of the viral envelope using pseudo-typed viruses, this phenomenon was independent of CD4 and enhanced infectivity. Next, we found that Nef not only possesses a consensus motif for but also binds AIP1 in vitro and in vivo. AIP1 is the critical intermediate in the formation of multivesicular bodies (MVBs), which play an important role in the budding and release of viruses from infected cells. Indeed, Nef proliferated MVBs in cells, but only when its AIP1-binding site was intact. Finally, these functions of Nef were reproduced in primary macrophages, where the wild type but not mutant Nef proteins led to increased release of new viral particles from infected cells. Conclusion We conclude that by binding GagPol and AIP1, Nef not only proliferates MVBs but also contributes to the egress of viral particles from infected cells.
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Affiliation(s)
- Luciana J Costa
- Molecular Virology Laboratory, Dep. of Genetics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Nan Chen
- Departments of Medicine, Microbiology and Immunology, Rosalind Russell Medical Research Center, University of California at San Francisco, San Francisco, CA, USA
| | - Adriana Lopes
- Molecular Virology Laboratory, Dep. of Genetics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Renato S Aguiar
- Molecular Virology Laboratory, Dep. of Genetics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Amilcar Tanuri
- Molecular Virology Laboratory, Dep. of Genetics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Ana Plemenitas
- Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - B Matija Peterlin
- Departments of Medicine, Microbiology and Immunology, Rosalind Russell Medical Research Center, University of California at San Francisco, San Francisco, CA, USA
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Agopian K, Wei BL, Garcia JV, Gabuzda D. A hydrophobic binding surface on the human immunodeficiency virus type 1 Nef core is critical for association with p21-activated kinase 2. J Virol 2006; 80:3050-61. [PMID: 16501114 PMCID: PMC1395437 DOI: 10.1128/jvi.80.6.3050-3061.2006] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The interaction of human immunodeficiency virus type 1 (HIV-1) Nef with p21-activated kinase 2 (Pak2) has been proposed to play an important role in T-cell activation and disease progression during viral infection. However, the mechanism by which Nef activates Pak2 is poorly understood. Mutations in most Nef motifs previously reported to be required for Pak2 activation (G2, PxxP72, and RR105) also affect other Nef functions, such as CD4 or major histocompatibility complex class I (MHC-I) downregulation. To better understand Nef interactions with Pak2, we performed mutational analysis of three primary HIV-1 Nef clones that exhibited similar capacities for downregulation of CD4 and MHC-I but variable abilities to associate with activated Pak2. Our results demonstrate that Nef amino acids at positions 85, 89, 187, 188, and 191 (L, H, S, R, and F in the clade B consensus, respectively) are critical for Pak2 association. Mutation of these Nef residues dramatically altered association with Pak2 without affecting Nef expression levels or CD4 and MHC-I downregulation. Furthermore, compensation occurred at positions 89 and 191 when both amino acids were substituted. Since residues 85, 89, 187, 188, and 191 cluster on the surface of the Nef core domain in a region distinct from the dimerization and SH3-binding domains, we propose that these Nef residues form part of a unique binding surface specifically involved in association with Pak2. This binding surface includes exposed and recessed hydrophobic residues and may participate in an as-yet-unidentified protein-protein interaction to facilitate Pak2 activation.
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Affiliation(s)
- Kristin Agopian
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Harvard Medical School, JFB 816, 44 Binney St., Boston, Massachusetts 02115, USA
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Wilkes MC, Mitchell H, Penheiter SG, Doré JJ, Suzuki K, Edens M, Sharma DK, Pagano RE, Leof EB. Transforming growth factor-beta activation of phosphatidylinositol 3-kinase is independent of Smad2 and Smad3 and regulates fibroblast responses via p21-activated kinase-2. Cancer Res 2006; 65:10431-40. [PMID: 16288034 DOI: 10.1158/0008-5472.can-05-1522] [Citation(s) in RCA: 165] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Transforming growth factor-beta (TGF-beta) stimulates cellular proliferation and transformation to a myofibroblast phenotype in vivo and in a subset of fibroblast cell lines. As the Smad pathway is activated by TGF-beta in essentially all cell types, it is unlikely to be the sole mediator of cell type-specific outcomes to TGF-beta stimulation. In the current study, we determined that TGF-beta receptor signaling activates phosphatidylinositol 3-kinase (PI3K) in several fibroblast but not epithelial cultures independently of Smad2 and Smad3. PI3K activation occurs in the presence of dominant-negative dynamin and is required for p21-activated kinase-2 kinase activity and the increased proliferation and morphologic change induced by TGF-beta in vitro.
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Affiliation(s)
- Mark C Wilkes
- Department of Biochemistry and Molecular Biology, Thoracic Diseases Research Unit, and Mayo Clinic Cancer Center, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA
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The Role of Phosphoinositide 3-Kinase-Akt Signaling in Virus Infection. APOPTOSIS, CELL SIGNALING, AND HUMAN DISEASES 2006. [PMCID: PMC7120950 DOI: 10.1007/978-1-59745-199-4_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Audigé A, Schlaepfer E, Joller H, Speck RF. Uncoupled anti-HIV and immune-enhancing effects when combining IFN-alpha and IL-7. THE JOURNAL OF IMMUNOLOGY 2005; 175:3724-36. [PMID: 16148118 DOI: 10.4049/jimmunol.175.6.3724] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Cytokine-based therapies have been examined for purging viral reservoirs and immunomodulation in HIV infection. However, single cytokines did not result in either HIV eradication or an efficient HIV-specific immune response. We hypothesize that cytokines with distinct biologic effects need to be combined for immunotherapy of HIV infection. In this study, we investigated the anti-HIV activity and immune-enhancing effects of the combination of IFN-alpha and IL-7. In human lymphocyte aggregate cultures infected ex vivo with the X4 HIV strain NL4-3, IFN-alpha/IL-7 potently inhibited HIV replication and preserved CD4(+) T cells, probably by up-regulating Bcl-2. IFN-alpha/IL-7 also strongly inhibited R5 HIV replication. Furthermore, in allogeneic MLRs, IFN-alpha/IL-7 increased T cell proliferation and IFN-gamma production. IFN-alpha alone also had strong anti-HIV activity, but neither preserved CD4(+) T cells nor increased T cell responses in MLRs. IL-7 alone maintained T cells and enhanced T cell activation in MLRs, but only moderately inhibited or increased HIV replication. Thus, coadministration of IFN-alpha/IL-7 combines the potent anti-HIV activity of IFN-alpha with the beneficial effects of IL-7 on T cell survival and function. We speculate that IFN-alpha will block viral replication, activate APCs, and up-regulate MHC molecules, thus allowing IL-7 to display its effects for generating an efficient immune response. In this scenario, the known reactivation of latent HIV by IL-7 may be advantageous.
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Affiliation(s)
- Annette Audigé
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital of Zurich, Zurich, Switzerland.
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Fenard D, Yonemoto W, de Noronha C, Cavrois M, Williams SA, Greene WC. Nef is physically recruited into the immunological synapse and potentiates T cell activation early after TCR engagement. THE JOURNAL OF IMMUNOLOGY 2005; 175:6050-7. [PMID: 16237100 DOI: 10.4049/jimmunol.175.9.6050] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The HIV-1 protein Nef enhances viral pathogenicity and accelerates disease progression in vivo. Nef potentiates T cell activation by an unknown mechanism, probably by optimizing the intracellular environment for HIV replication. Using a new T cell reporter system, we have found that Nef more than doubles the number of cells expressing the transcription factors NF-kappaB and NFAT after TCR stimulation. This Nef-induced priming of TCR signaling pathways occurred independently of calcium signaling and involved a very proximal step before protein kinase C activation. Engagement of the TCR by MHC-bound Ag triggers the formation of the immunological synapse by recruiting detergent-resistant membrane microdomains, termed lipid rafts. Approximately 5-10% of the total cellular pool of Nef is localized within lipid rafts. Using confocal and real-time microscopy, we found that Nef in lipid rafts was recruited into the immunological synapse within minutes after Ab engagement of the TCR/CD3 and CD28 receptors. This recruitment was dependent on the N-terminal domain of Nef encompassing its myristoylation. Nef did not increase the number of cell surface lipid rafts or immunological synapses. Recently, studies have shown a specific interaction of Nef with an active subpopulation of p21-activated kinase-2 found only in the lipid rafts. Thus, the corecruitment of Nef and key cellular partners (e.g., activated p21-activated kinase-2) into the immunological synapse may underlie the increased frequency of cells expressing transcriptionally active forms of NF-kappaB and NFAT and the resultant changes in T cell activation.
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Affiliation(s)
- David Fenard
- Gladstone Institute of Virology and Immunology, University of California, 94158, USA
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Raney A, Kuo LS, Baugh LL, Foster JL, Garcia JV. Reconstitution and molecular analysis of an active human immunodeficiency virus type 1 Nef/p21-activated kinase 2 complex. J Virol 2005; 79:12732-41. [PMID: 16188976 PMCID: PMC1235864 DOI: 10.1128/jvi.79.20.12732-12741.2005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) Nef activation of p21-activated kinase 2 (PAK-2) was recapitulated in a cell-free system consisting of in vitro-transcribed RNA, rabbit reticulocyte lysate, and microsomal membranes on the basis of the following observations: (i) Nef associated with a kinase endogenous to the rabbit reticulocyte lysate that was identified as PAK-2, (ii) Nef-associated kinase activity was detected with Nefs from HIV-1(SF2), HIV-1(YU2), and SIV(mac239), (iii) kinase activation was not detected with a myristoylation-defective Nef (HIV-1(SF2)NefG2A) or with a Nef defective in PAK-2 activation but fully competent in other Nef functions (HIV-1(SF2)NefF195I), and (iv) Nef-associated kinase activation required activated endogenous p21 GTPases (Rac1 or Cdc42). The cell-free system was used to analyze the mechanism of Nef activation of PAK-2. First, studies suggest that the p21 GTPases may act transiently to enhance Nef activation of PAK-2 in vitro. Second, addition of wortmannin to the cell-free system demonstrated that Nef activation of PAK-2 does not require PI 3-kinase activity. Third, ultracentrifugation analysis revealed that whereas the majority of Nef and PAK-2 partitioned to the supernatant, Nef-associated PAK-2 activity partitioned to the membrane-containing pellet as a low-abundance complex. Lastly, Nef activation of PAK-2 in vitro requires addition of microsomal membranes either during or after translation of the Nef RNA. These results are consistent with a model in which activation of PAK-2 by Nef occurs by recruiting PAK-2 to membranes. As demonstrated herein, the cell-free system is a new and important tool in the investigation of the mechanism of PAK-2 activation by Nef.
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Affiliation(s)
- Alexa Raney
- Department of Internal Medicine, Division of Infectious Diseases, University of Texas Southwestern Medical Center at Dallas, 75390-9113, USA
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Rajala MS, Rajala RVS, Astley RA, Butt AL, Chodosh J. Corneal cell survival in adenovirus type 19 infection requires phosphoinositide 3-kinase/Akt activation. J Virol 2005; 79:12332-41. [PMID: 16160160 PMCID: PMC1211526 DOI: 10.1128/jvi.79.19.12332-12341.2005] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2005] [Accepted: 07/13/2005] [Indexed: 02/04/2023] Open
Abstract
Adenovirus type 19 is a major cause of epidemic keratoconjunctivitis, the only ocular adenoviral infection associated with prolonged corneal inflammation. In this study, we investigated the role of phosphoinositide 3-kinase (PI3K) and Akt and their downstream targets in adenovirus infection, and here we report the novel finding that adenovirus type 19 utilizes the PI3K/Akt pathway to maintain corneal fibroblast viability in acute infection. We demonstrate phosphorylation of GSK-3beta and nuclear translocation of the p65 subunit of NF-kappaB, both downstream targets of the PI3K/Akt pathway, in adenovirus-infected corneal fibroblasts in a PI3K-dependent manner. Inhibition of PI3K had no effect on early viral gene expression, suggesting normal viral internalization, but pretreatment with the PI3K inhibitor LY294002 or overexpression of dominant negative Akt induced early cytopathic effect and caspase-mediated cell death in adenovirus-infected cells. Early cell death could be circumvented despite LY294002 by overexpression of constitutively active Akt. Furthermore, we show an interaction between cSrc and the p85 regulatory subunit of PI3K in infected cells through a phosphorylation-dependent mechanism. The results presented in this paper provide the first direct evidence that PI3K-mediated Akt activation in adenovirus-infected corneal cells may contribute to viral pathogenesis by the prolongation of cell viability.
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Affiliation(s)
- Maitreyi S Rajala
- Molecular Pathogenesis of Eye Infection Research Center, Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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47
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Choi J, Walker J, Talbert-Slagle K, Wright P, Pober JS, Alexander L. Endothelial cells promote human immunodeficiency virus replication in nondividing memory T cells via Nef-, Vpr-, and T-cell receptor-dependent activation of NFAT. J Virol 2005; 79:11194-204. [PMID: 16103171 PMCID: PMC1193601 DOI: 10.1128/jvi.79.17.11194-11204.2005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human endothelial cells (ECs) enhance human immunodeficiency virus (HIV) replication within CD4(+) memory T cells by 50,000-fold in a Nef-dependent manner. Here, we report that EC-mediated HIV type 1 replication is also dependent on an intact vpr gene. Moreover, we demonstrate that despite a requirement for engaging major histocompatibility complex (MHC) class II molecules and costimulators, EC-stimulated virus-producing cells (p24(high) T cells) do not proliferate, nor are they arrested in the cell cycle. Rather, they are minimally activated, sometimes expressing CD69 but not CD25, HLA-DR, VLA-1, or effector cytokines. Blocking antibodies to interleukin 2 (IL-2), IL-6, IL-7, or tumor necrosis factor do not inhibit viral replication. Cyclosporine effectively inhibits viral replication, as does disruption of the NFAT binding site in the viral long terminal repeat. Furthermore, in the presence of ECs, suboptimal T-cell receptor (TCR) stimulation with phytohemagglutinin L supports efficient viral replication, and suboptimal stimulation with toxic shock syndrome toxin 1 leads to viral replication selectively in the TCR-stimulated, Vbeta2-expressing T cells. Collectively, these data indicate that ECs provide signals that promote Nef- and Vpr-dependent HIV replication in memory T cells that have been minimally activated through their TCRs. Our studies suggest a mechanism for HIV replication in vivo within the reservoir of circulating memory CD4(+) T cells that persist despite antiretroviral therapy and further suggest that maintenance of immunological memory by MHC class II-expressing ECs via TCR signaling may contribute to HIV rebound following cessation of antiretroviral therapy.
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Affiliation(s)
- Jaehyuk Choi
- Section of Immunology, Yale University School of Medicine, New Haven, CT 06520, USA
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Pulkkinen K, Renkema GH, Kirchhoff F, Saksela K. Nef associates with p21-activated kinase 2 in a p21-GTPase-dependent dynamic activation complex within lipid rafts. J Virol 2004; 78:12773-80. [PMID: 15542629 PMCID: PMC524974 DOI: 10.1128/jvi.78.23.12773-12780.2004] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have previously reported that Nef specifically interacts with a small but highly active subpopulation of p21-activated kinase 2 (PAK2). Here we show that this is due to a transient association of Nef with a PAK2 activation complex within a detergent-insoluble membrane compartment containing the lipid raft marker GM1. The low abundance of this Nef-associated kinase (NAK) complex was found to be due to an autoregulatory mechanism. Although activation of PAK2 was required for assembly of the NAK complex, catalytic activity of PAK2 also promoted dissociation of this complex. Testing different constitutively active PAK2 mutants indicated that the conformation associated with p21-mediated activation rather than kinase activity per se was required for PAK2 to become NAK. Although association with PAK2 is one of the most conserved properties of Nef, we found that the ability to stimulate PAK2 activity differed markedly among divergent Nef alleles, suggesting that PAK2 association and activation are distinct functions of Nef. However, mutations introduced into the p21-binding domain of PAK2 revealed that p21-GTPases are involved in both of these Nef functions and, in addition to promoting PAK2 activation, also help to physically stabilize the NAK complex.
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Affiliation(s)
- Kati Pulkkinen
- Institute of Medical Technology, FIN-33014, University of Tampere, Tampere, Finland
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Abstract
The major histocompatibility (MHC) class I antigen presentation pathway plays a pivotal role in immunity to viruses. MHC class I molecules are expressed on the cell surface of all nucleated cells and present peptides derived from intracellular proteins to cytotoxic T lymphocytes (CTLs), which then eliminate virally infected cells. However, many viruses have evolved proteins to inhibit the MHC class I pathway, thus enabling virally infected cells to escape CTL lysis. In this review, we summarize recent findings about viral inhibition of the MHC class I pathway.
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Affiliation(s)
- Eric W Hewitt
- School of Biochemistry and Microbiology, University of Leeds, Leeds, LS2 9JT, UK.
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He JC, Husain M, Sunamoto M, D'Agati VD, Klotman ME, Iyengar R, Klotman PE. Nef stimulates proliferation of glomerular podocytes through activation of Src-dependent Stat3 and MAPK1,2 pathways. J Clin Invest 2004; 114:643-51. [PMID: 15343382 PMCID: PMC514582 DOI: 10.1172/jci21004] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2004] [Accepted: 07/15/2004] [Indexed: 11/17/2022] Open
Abstract
In collapsing focal segmental glomerulosclerosis (FSGS) of HIV-associated nephropathy (HIVAN), podocytes exhibit a high proliferation rate and loss of differentiation markers. We have found previously that the nef gene of HIV-1 is responsible for these changes. Here, we investigated the signaling pathways induced by Nef and its role in the pathogenesis of HIVAN. Using conditionally immortalized podocytes after differentiation, we found that infection of podocytes with nef increased Src kinase activity and signal transducer and activator of transcription 3 (Stat3) phosphorylation and activated the Ras-c-Raf-MAPK1,2 pathway. A dominant negative mutant of Src abolished the Nef effect, whereas inhibition of MAPK1,2 or dominant negative Stat3 reduced Nef effects partially. Reducing the expression of Nef with small interference RNA reversed the Nef effect. Mutation of Nef in the PxxP or R105R106 motifs diminished Nef signaling and the phenotypic changes in podocytes. Both phospho-MAPK1,2 and phospho-Stat3 staining increased in podocytes of kidneys from HIV-1 transgenic mice compared with their littermates and in podocytes of kidneys from HIVAN patients compared with HIV patients with non-HIVAN kidney diseases or non-HIV patients with idiopathic FSGS, classic FSGS, or minimal-change disease. These data suggest that Nef-induced activation of Stat3 and Ras-MAPK1,2 via Src-dependent pathways is responsible for podocyte proliferation and dedifferentiation, a characteristic finding in collapsing FSGS of HIVAN.
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Affiliation(s)
- John Cijiang He
- Department of Medicine, Mount Sinai School of Medicine, New York, New York, USA.
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