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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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Zhao B, Barrera LA, Ersing I, Willox B, Schmidt SCS, Greenfeld H, Zhou H, Mollo SB, Shi TT, Takasaki K, Jiang S, Cahir-McFarland E, Kellis M, Bulyk ML, Kieff E, Gewurz BE. The NF-κB genomic landscape in lymphoblastoid B cells. Cell Rep 2014; 8:1595-606. [PMID: 25159142 DOI: 10.1016/j.celrep.2014.07.037] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 06/09/2014] [Accepted: 07/21/2014] [Indexed: 01/17/2023] Open
Abstract
The nuclear factor κB (NF-κΒ) subunits RelA, RelB, cRel, p50, and p52 are each critical for B cell development and function. To systematically characterize their responses to canonical and noncanonical NF-κB pathway activity, we performed chromatin immunoprecipitation followed by high-throughput DNA sequencing (ChIP-seq) analysis in lymphoblastoid B cell lines (LCLs). We found a complex NF-κB-binding landscape, which did not readily reflect the two NF-κB pathway paradigms. Instead, 10 subunit-binding patterns were observed at promoters and 11 at enhancers. Nearly one-third of NF-κB-binding sites lacked κB motifs and were instead enriched for alternative motifs. The oncogenic forkhead box protein FOXM1 co-occupied nearly half of NF-κB-binding sites and was identified in protein complexes with NF-κB on DNA. FOXM1 knockdown decreased NF-κB target gene expression and ultimately induced apoptosis, highlighting FOXM1 as a synthetic lethal target in B cell malignancy. These studies provide a resource for understanding mechanisms that underlie NF-κB nuclear activity and highlight opportunities for selective NF-κB blockade.
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Affiliation(s)
- Bo Zhao
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Luis A Barrera
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA; Harvard Medical School, Boston, MA 02115, USA; Committee on Higher Degrees in Biophysics, Harvard University, Cambridge, MA 02138, USA; Harvard-MIT Division of Health Sciences and Technology, Harvard Medical School, Boston, MA 02115, USA; Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Ina Ersing
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Bradford Willox
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Stefanie C S Schmidt
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Hannah Greenfeld
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Hufeng Zhou
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Sarah B Mollo
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Tommy T Shi
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Kaoru Takasaki
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Sizun Jiang
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Ellen Cahir-McFarland
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Manolis Kellis
- Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Martha L Bulyk
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA; Harvard Medical School, Boston, MA 02115, USA; Committee on Higher Degrees in Biophysics, Harvard University, Cambridge, MA 02138, USA; Harvard-MIT Division of Health Sciences and Technology, Harvard Medical School, Boston, MA 02115, USA; Department of Pathology, Brigham and Women's Hospital, Boston, MA 02115, USA.
| | - Elliott Kieff
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Benjamin E Gewurz
- Division of Infectious Disease, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA.
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Tokarev A, Suarez M, Kwan W, Fitzpatrick K, Singh R, Guatelli J. Stimulation of NF-κB activity by the HIV restriction factor BST2. J Virol 2013; 87:2046-57. [PMID: 23221546 PMCID: PMC3571454 DOI: 10.1128/jvi.02272-12] [Citation(s) in RCA: 150] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 11/21/2011] [Indexed: 11/20/2022] Open
Abstract
BST2 (HM1.24; CD317; tetherin) is an interferon-inducible transmembrane protein that restricts the release of several enveloped viruses, including HIV, from infected cells. Before its activity as an antiviral factor was described, BST2 was identified as an inducer of NF-κB activity. Here we show that human BST2 induces NF-κB in a dose-dependent manner. This activity is separable from the restriction of virus release: a YxY sequence in the cytoplasmic domain of BST2 is required for the induction of NF-κB but is dispensable for restriction, whereas the glycosylphosphatidylinositol (GPI) addition site in the protein's ectodomain is required for restriction but is largely dispensable for the induction of NF-κB. Mutations predicted to disrupt the coiled-coil structure of the BST2 ectodomain impaired both signaling and restriction, but disruption of the tetramerization interface differentially affected signaling. The induction of NF-κB by BST2 was impaired by inhibition of transforming growth factor β (TGF-β)-activated kinase 1 (TAK1) or by calcium chelation, suggesting potential linkage to the mitogen-activated protein kinase and endoplasmic reticulum (ER) stress response pathways. Consistent with a role for TAK1, BST2 coimmunoprecipitated with TAK1 and the TAK1-associated pseudophosphatase TAB1; these interactions required the YxY sequence in BST2. Moreover, signaling by BST2 was blocked by expression of an IκB-mutant that inhibits the canonical pathway of NF-κB activation. The expression of HIV-1 Vpu inhibited the induction of NF-κB by BST2; this inhibition required Vpu's ability to bind the cellular β-TrCP-E3-ubiquitin ligase complex. The expression of HIV-1 lacking vpu augmented the induction of NF-κB activity by BST2, suggesting that BST2 can act as a virus sensor. This augmentation was also inhibited by Vpu in a β-TrCP-dependent manner. The role of BST2 in the host-pathogen relationship is apparently multifaceted: signaling during the innate immune response, sensing of viral gene expression, and direct restriction of virus release. HIV-1 Vpu counteracts each of these functions.
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Affiliation(s)
- Andrey Tokarev
- The University of California—San Diego, La Jolla California, USA
| | - Marissa Suarez
- The Veterans Affairs San Diego Healthcare System, San Diego, California, USA
| | - Wilson Kwan
- The University of California—San Diego, La Jolla California, USA
| | | | - Rajendra Singh
- The University of California—San Diego, La Jolla California, USA
| | - John Guatelli
- The University of California—San Diego, La Jolla California, USA
- The Veterans Affairs San Diego Healthcare System, San Diego, California, USA
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Abstract
Central to NF-κB signaling pathways is IKKγ/NEMO, a regulatory subunit of the cytoplasmic IκB kinase (IKK) complex, which undergoes various posttranslational modifications, specifically phosphorylation, to regulate its function. Furthermore, Kaposi’s sarcoma-associated herpesvirus (KSHV) FADD-like interleukin-1β (IL-1β) converting enzyme (FLICE) inhibitory protein (vFLIP) activates the NF-κB signaling pathway by directly interacting with IKKγ/NEMO. However, the exact functions of IKKγ/NEMO phosphorylation and its KvFLIP interaction in NF-κB activation remain elusive. Here, we report two novel phosphorylation sites of IKKγ/NEMO and their negative effect on the IKKγ/NEMO-mediated NF-κB signaling pathway. First, the Src family protein tyrosine kinases (SF-PTKs), including Src, Fyn, Lyn, and Fgr, interact with and phosphorylate tyrosine residue 374 (Y374) of IKKγ/NEMO. Mutation of the Y374 residue to phenylalanine (Y374F) specifically abolished SF-PTK-mediated tyrosine phosphorylation, leading to increased tumor necrosis factor alpha (TNF-α)-induced NF-κB activity. Moreover, our mass spectrometry analysis found that the serine 377 residue (S377) of IKKγ/NEMO underwent robust phosphorylation upon KvFLIP expression. Replacement of the IKKγ/NEMO S377 residue by alanine (S377A) or glutamic acid (S377E) resulted in a significant increase or decrease of NF-κB activity and TNF-α-mediated IL-6 cytokine production, respectively. Our study thus demonstrates that the Y374 or S377 residue located at the C-terminal proline-rich domain of human IKKγ/NEMO undergoes phosphorylation upon TNF-α treatment or KvFLIP expression, respectively, resulting in the suppression of IKKγ/NEMO activity to induce NF-κB activation. This study suggests the potential phosphorylation-mediated feedback negative regulation of IKKγ/NEMO activity in the NF-κB signaling pathway. Since unchecked regulation of NF-κB has been linked to uncontrolled proliferation and cell death, the downregulation of the NF-κB signaling pathway is as important as its activation. Specifically, the phosphorylation-mediated modification of IKKγ/NEMO is a critical regulatory mechanism of NF-κB activity. Here, we report two novel phosphorylations of IKKγ/NEMO and their negative effects on the NF-κB signaling pathway. First, the Src family protein tyrosine kinase interacts with and phosphorylates tyrosine residue 374 of IKKγ/NEMO, suppressing tumor necrosis factor alpha (TNF-α)-induced NF-κB activity. Additionally, Kaposi’s sarcoma-associated herpesvirus (KSHV) FADD-like interleukin-1β (IL-1β) converting enzyme (FLICE) inhibitory protein (KvFLIP) expression induces a robust phosphorylation of the serine 377 residue of IKKγ/NEMO, resulting in a significant decrease of NF-κB activity. Our study thus demonstrates that the Y374 or S377 residue of IKKγ/NEMO undergoes phosphorylation upon TNF-α treatment or KvFLIP expression, respectively, resulting in the suppression of IKKγ/NEMO activity to induce NF-κB activation. This also suggests the potential phosphorylation-mediated feedback negative regulation of IKKγ/NEMO activity in the NF-κB signaling pathway.
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A 205-nucleotide deletion in the 3' untranslated region of avian leukosis virus subgroup J, currently emergent in China, contributes to its pathogenicity. J Virol 2012; 86:12849-60. [PMID: 22993155 DOI: 10.1128/jvi.01113-12] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
In the past 5 years, an atypical clinical outbreak of avian leukosis virus subgroup J (ALV-J), which contains a unique 205-nucleotide deletion in its 3' untranslated region (3'UTR), has become epidemic in chickens in China. To determine the role of the 205-nucleotide deletion in the pathogenicity of ALV-J, a pair of viruses were constructed and rescued. The first virus was an ALV-J Chinese isolate (designated HLJ09SH01) containing the 205-nucleotide deletion in its 3'UTR. The second virus was a chimeric clone in which the 3'UTR contains a 205-nucleotide sequence corresponding to a region of the ALV-J prototype virus. The replication and pathogenicity of the rescued viruses (rHLJ09SH01 and rHLJ09SH01A205) were investigated. Compared to rHLJ09SH01A205, rHLJ09SH01 showed a moderate growth advantage in vitro and in vivo, in addition to exhibiting a higher oncogenicity rate and lethality rate in layers and broilers. Increased vascular endothelial growth factor A (VEGF-A) and vascular endothelial growth receptor subtype 2 (VEGFR-2) expression was induced by rHLJ09SH01 more so than by rHLJ09SH01A205 during early embryonic vascular development, but this increased expression disappeared when the expression levels were normalized to the viral levels. This finding suggests that the expression of VEGF-A and VEGFR-2 is associated with viral replication and may also represent a novel molecular mechanism underlying the oncogenic potential of ALV-J. Overall, our findings not only indicate that the unique 205-nucleotide deletion in the ALV-J genome occurred naturally in China and contributes to increased pathogenicity but also point to the possible mechanism of ALV-J-induced oncogenicity.
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HIV-1 Nef induces proinflammatory state in macrophages through its acidic cluster domain: involvement of TNF alpha receptor associated factor 2. PLoS One 2011; 6:e22982. [PMID: 21886773 PMCID: PMC3160284 DOI: 10.1371/journal.pone.0022982] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2010] [Accepted: 07/11/2011] [Indexed: 01/06/2023] Open
Abstract
Background HIV-1 Nef is a virulence factor that plays multiple roles during HIV replication. Recently, it has been described that Nef intersects the CD40 signalling in macrophages, leading to modification in the pattern of secreted factors that appear able to recruit, activate and render T lymphocytes susceptible to HIV infection. The engagement of CD40 by CD40L induces the activation of different signalling cascades that require the recruitment of specific tumor necrosis factor receptor-associated factors (i.e. TRAFs). We hypothesized that TRAFs might be involved in the rapid activation of NF-κB, MAPKs and IRF-3 that were previously described in Nef-treated macrophages to induce the synthesis and secretion of proinflammatory cytokines, chemokines and IFNβ to activate STAT1, -2 and -3. Methodology/Principal Findings Searching for possible TRAF binding sites on Nef, we found a TRAF2 consensus binding site in the AQEEEE sequence encompassing the conserved four-glutamate acidic cluster. Here we show that all the signalling effects we observed in Nef treated macrophages depend on the integrity of the acidic cluster. In addition, Nef was able to interact in vitro with TRAF2, but not TRAF6, and this interaction involved the acidic cluster. Finally silencing experiments in THP-1 monocytic cells indicate that both TRAF2 and, surprisingly, TRAF6 are required for the Nef-induced tyrosine phosphorylation of STAT1 and STAT2. Conclusions Results reported here revealed TRAF2 as a new possible cellular interactor of Nef and highlighted that in monocytes/macrophages this viral protein is able to manipulate both the TRAF/NF-κB and TRAF/IRF-3 signalling axes, thereby inducing the synthesis of proinflammatory cytokines and chemokines as well as IFNβ.
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