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Olety B, Usami Y, Wu Y, Peters P, Göttlinger H. AP-2 Adaptor Complex-Dependent Enhancement of HIV-1 Replication by Nef in the Absence of the Nef/AP-2 Targets SERINC5 and CD4. mBio 2023; 14:e0338222. [PMID: 36622146 PMCID: PMC9973267 DOI: 10.1128/mbio.03382-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 12/08/2022] [Indexed: 01/10/2023] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) Nef hijacks the clathrin adaptor complex 2 (AP-2) to downregulate the viral receptor CD4 and the antiviral multipass transmembrane proteins SERINC3 and SERINC5, which inhibit the infectivity of progeny virions when incorporated. In Jurkat Tag T lymphoid cells lacking SERINC3 and SERINC5, Nef is no longer required for full progeny virus infectivity and for efficient viral replication. However, in MOLT-3 T lymphoid cells, HIV-1 replication remains highly dependent on Nef even in the absence of SERINC3 and SERINC5. Using a knockout (KO) approach, we now show that the Nef-mediated enhancement of HIV-1 replication in MOLT-3 cells does not depend on the Nef-interacting kinases LCK and PAK2. Furthermore, Nef substantially enhanced HIV-1 replication even in triple-KO MOLT-3 cells that simultaneously lacked the three Nef/AP-2 targets, SERINC3, SERINC5, and CD4, and were reconstituted with a Nef-resistant CD4 to permit HIV-1 entry. Nevertheless, the ability of Nef mutants to promote HIV-1 replication in the triple-KO cells correlated strictly with the ability to bind AP-2. In addition, knockdown and reconstitution experiments confirmed the involvement of AP-2. These observations raise the possibility that MOLT-3 cells express a novel antiviral factor that is downregulated by Nef in an AP-2-dependent manner. IMPORTANCE The HIV-1 Nef protein hijacks a component of the cellular endocytic machinery called AP-2 to downregulate the viral receptor CD4 and the antiviral cellular membrane proteins SERINC3 and SERINC5. In the absence of Nef, SERINC3 and SERINC5 are taken up into viral particles, which reduces their infectivity. Surprisingly, in a T cell line called MOLT-3, Nef remains crucial for HIV-1 spreading in the absence of SERINC3 and SERINC5. We now show that this effect of Nef also does not depend on the cellular signaling molecules and Nef interaction partners LCK and PAK2. Nef was required for efficient HIV-1 spreading even in triple-knockout cells that completely lacked Nef/AP-2-sensitive CD4, in addition to the Nef/AP-2 targets SERINC3 and SERINC5. Nevertheless, our results indicate that the enhancement of HIV-1 spreading by Nef in the triple-knockout cells remained AP-2 dependent, which suggests the presence of an unknown antiviral factor that is sensitive to Nef/AP-2-mediated downregulation.
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Affiliation(s)
- Balaji Olety
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Yoshiko Usami
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Yuanfei Wu
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Paul Peters
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Heinrich Göttlinger
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
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2
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Zhao Z, Fagerlund R, Tossavainen H, Hopfensperger K, Lotke R, Srinivasachar Badarinarayan S, Kirchhoff F, Permi P, Sato K, Sauter D, Saksela K. Evolutionary plasticity of SH3 domain binding by Nef proteins of the HIV-1/SIVcpz lentiviral lineage. PLoS Pathog 2021; 17:e1009728. [PMID: 34780577 PMCID: PMC8629392 DOI: 10.1371/journal.ppat.1009728] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 11/29/2021] [Accepted: 10/28/2021] [Indexed: 11/18/2022] Open
Abstract
The accessory protein Nef of human and simian immunodeficiency viruses (HIV and SIV) is an important pathogenicity factor known to interact with cellular protein kinases and other signaling proteins. A canonical SH3 domain binding motif in Nef is required for most of these interactions. For example, HIV-1 Nef activates the tyrosine kinase Hck by tightly binding to its SH3 domain. An archetypal contact between a negatively charged SH3 residue and a highly conserved arginine in Nef (Arg77) plays a key role here. Combining structural analyses with functional assays, we here show that Nef proteins have also developed a distinct structural strategy—termed the "R-clamp”—that favors the formation of this salt bridge via buttressing Arg77. Comparison of evolutionarily diverse Nef proteins revealed that several distinct R-clamps have evolved that are functionally equivalent but differ in the side chain compositions of Nef residues 83 and 120. Whereas a similar R-clamp design is shared by Nef proteins of HIV-1 groups M, O, and P, as well as SIVgor, the Nef proteins of SIV from the Eastern chimpanzee subspecies (SIVcpzP.t.s.) exclusively utilize another type of R-clamp. By contrast, SIV of Central chimpanzees (SIVcpzP.t.t.) and HIV-1 group N strains show more heterogenous R-clamp design principles, including a non-functional evolutionary intermediate of the aforementioned two classes. These data add to our understanding of the structural basis of SH3 binding and kinase deregulation by Nef, and provide an interesting example of primate lentiviral protein evolution. Viral replication depends on interactions with a plethora of host cell proteins. Cellular protein interactions are typically mediated by specialized binding modules, such as the SH3 domain. To gain access to host cell regulation viruses have evolved to contain SH3 domain binding sites in their proteins, a notable example of which is the HIV-1 Nef protein. Here we show that during the primate lentivirus evolution the structural strategy that underlies the avid binding of Nef to cellular SH3 domains, which we have dubbed the R-clamp, has been generated via alternative but functionally interchangeable molecular designs. These patterns of SH3 recognition depend on the amino acid combinations at the positions corresponding to residues 83 and 120 in the consensus HIV-1 Nef sequence, and are distinctly different in Nef proteins from SIVs of Eastern and Central chimpanzees, gorillas, and the four groups of HIV-1 that have independently originated from the latter two. These results highlight the evolutionary plasticity of viral proteins, and have implications on therapeutic development aiming to interfere with SH3 binding of Nef.
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Affiliation(s)
- Zhe Zhao
- Department of Virology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Riku Fagerlund
- Department of Virology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Helena Tossavainen
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
| | - Kristina Hopfensperger
- Institute for Medical Virology and Epidemiology of Viral Diseases, University Hospital Tübingen, Tübingen, Germany
| | - Rishikesh Lotke
- Institute for Medical Virology and Epidemiology of Viral Diseases, University Hospital Tübingen, Tübingen, Germany
| | | | - Frank Kirchhoff
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | - Perttu Permi
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
- Department of Chemistry, Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Kei Sato
- Division of Systems Virology, Department of Infectious Disease Control, International Research Center for Infectious Diseases, Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Daniel Sauter
- Institute for Medical Virology and Epidemiology of Viral Diseases, University Hospital Tübingen, Tübingen, Germany
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | - Kalle Saksela
- Department of Virology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
- * E-mail:
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3
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Kumar A, Mahajan A, Salazar EA, Pruitt K, Guzman CA, Clauss MA, Almodovar S, Dhillon NK. Impact of human immunodeficiency virus on pulmonary vascular disease. Glob Cardiol Sci Pract 2021; 2021:e202112. [PMID: 34285903 PMCID: PMC8272407 DOI: 10.21542/gcsp.2021.12] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Accepted: 05/31/2021] [Indexed: 01/08/2023] Open
Abstract
With the advent of anti-retroviral therapy, non-AIDS-related comorbidities have increased in people living with HIV. Among these comorbidities, pulmonary hypertension (PH) is one of the most common causes of morbidity and mortality. Although chronic HIV-1 infection is independently associated with the development of pulmonary arterial hypertension, PH in people living with HIV may also be the outcome of various co-morbidities commonly observed in these individuals including chronic obstructive pulmonary disease, left heart disease and co-infections. In addition, the association of these co-morbidities and other risk factors, such as illicit drug use, can exacerbate the development of pulmonary vascular disease. This review will focus on these complex interactions contributing to PH development and exacerbation in HIV patients. We also examine the interactions of HIV proteins, including Nef, Tat, and gp120 in the pulmonary vasculature and how these proteins alter the endothelial and smooth muscle function by transforming them into susceptible PH phenotype. The review also discusses the available infectious and non-infectious animal models to study HIV-associated PAH, highlighting the advantages and disadvantages of each model, along with their ability to mimic the clinical manifestations of HIV-PAH.
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Affiliation(s)
- Ashok Kumar
- Pulmonary, Critical Care and Sleep Medicine, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Aatish Mahajan
- Pulmonary, Critical Care and Sleep Medicine, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Ethan A Salazar
- Department of Immunology & Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, Texas, USA
| | - Kevin Pruitt
- Department of Immunology & Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, Texas, USA
| | - Christian Arce Guzman
- Pulmonary, Critical Care, Sleep & Occupational Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Matthias A Clauss
- Pulmonary, Critical Care, Sleep & Occupational Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Sharilyn Almodovar
- Department of Immunology & Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, Texas, USA
| | - Navneet K Dhillon
- Pulmonary, Critical Care and Sleep Medicine, University of Kansas Medical Center, Kansas City, Kansas, USA
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4
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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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Staudt RP, Alvarado JJ, Emert-Sedlak LA, Shi H, Shu ST, Wales TE, Engen JR, Smithgall TE. Structure, function, and inhibitor targeting of HIV-1 Nef-effector kinase complexes. J Biol Chem 2020; 295:15158-15171. [PMID: 32862141 DOI: 10.1074/jbc.rev120.012317] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/28/2020] [Indexed: 11/06/2022] Open
Abstract
Antiretroviral therapy has revolutionized the treatment of AIDS, turning a deadly disease into a manageable chronic condition. Life-long treatment is required because existing drugs do not eradicate HIV-infected cells. The emergence of drug-resistant viral strains and uncertain vaccine prospects highlight the pressing need for new therapeutic approaches with the potential to clear the virus. The HIV-1 accessory protein Nef is essential for viral pathogenesis, making it a promising target for antiretroviral drug discovery. Nef enhances viral replication and promotes immune escape of HIV-infected cells but lacks intrinsic enzymatic activity. Instead, Nef works through diverse interactions with host cell proteins primarily related to kinase signaling pathways and endosomal trafficking. This review emphasizes the structure, function, and biological relevance of Nef interactions with host cell protein-tyrosine kinases in the broader context of Nef functions related to enhancement of the viral life cycle and immune escape. Drug discovery targeting Nef-mediated kinase activation has allowed identification of promising inhibitors of multiple Nef functions. Pharmacological inhibitors of Nef-induced MHC-I down-regulation restore the adaptive immune response to HIV-infected cells in vitro and have the potential to enhance immune recognition of latent viral reservoirs as part of a strategy for HIV clearance.
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Affiliation(s)
- Ryan P Staudt
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - John J Alvarado
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Lori A Emert-Sedlak
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Haibin Shi
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Sherry T Shu
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Thomas E Wales
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts, USA
| | - John R Engen
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts, USA
| | - Thomas E Smithgall
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
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Jin SW, Markle TJ, Anmole G, Rahimi A, Kuang XT, Brumme ZL, Brockman MA. Modulation of TCR-dependent NFAT signaling is impaired in HIV-1 Nef isolates from elite controllers. Virology 2019; 530:39-50. [PMID: 30780124 DOI: 10.1016/j.virol.2019.02.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 02/09/2019] [Accepted: 02/10/2019] [Indexed: 12/24/2022]
Abstract
HIV-1 Nef modulates the activation state of CD4+ T cells by altering signaling events elicited by the T cell receptor (TCR). Primary nef sequences exhibit extensive inter-individual diversity that influences their ability to downregulate CD4 and HLA class I; however, the impact of nef variation on modulation of T cell signaling is poorly characterized. Here, we measured TCR-mediated activation of NFAT transcription factor in the presence of nef alleles isolated from 45 elite controllers (EC) and 46 chronic progressors (CP). EC Nef clones displayed lower ability to inhibit NFAT signaling (median 87 [IQR 75-93]% relative to SF2 Nef) compared to CP clones (94 [IQR 89-98]%) (p < 0.001). Polymorphisms in Nef's N-terminal domain impaired its ability to inhibit NFAT signaling. Results indicate that primary nef alleles exhibit a range of abilities to modulate TCR-dependent NFAT signaling, implicating natural variation in this function as a potential contributor to differential HIV-1 pathogenesis.
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Affiliation(s)
- Steven W Jin
- Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada
| | - Tristan J Markle
- Dept. of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
| | - Gursev Anmole
- Dept. of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
| | - Asa Rahimi
- Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada
| | - Xiaomei T Kuang
- Dept. of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
| | - Zabrina L Brumme
- Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada; British Columbia Centre for Excellence in HIV/AIDS, Vancouver, BC, Canada
| | - Mark A Brockman
- Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada; Dept. of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada; British Columbia Centre for Excellence in HIV/AIDS, Vancouver, BC, Canada.
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7
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Del Río-Iñiguez I, Vázquez-Chávez E, Cuche C, Di Bartolo V, Bouchet J, Alcover A. HIV-1 Nef Hijacks Lck and Rac1 Endosomal Traffic To Dually Modulate Signaling-Mediated and Actin Cytoskeleton-Mediated T Cell Functions. THE JOURNAL OF IMMUNOLOGY 2018; 201:2624-2640. [PMID: 30282749 DOI: 10.4049/jimmunol.1800372] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 09/03/2018] [Indexed: 01/03/2023]
Abstract
Endosomal traffic of TCR and signaling molecules regulates immunological synapse formation and T cell activation. We recently showed that Rab11 endosomes regulate the subcellular localization of the tyrosine kinase Lck and of the GTPase Rac1 and control their functions in TCR signaling and actin cytoskeleton remodeling. HIV-1 infection of T cells alters their endosomal traffic, activation capacity, and actin cytoskeleton organization. The viral protein Nef is pivotal for these modifications. We hypothesized that HIV-1 Nef could jointly alter Lck and Rac1 endosomal traffic and concomitantly modulate their functions. In this study, we show that HIV-1 infection of human T cells sequesters both Lck and Rac1 in a pericentrosomal compartment in an Nef-dependent manner. Strikingly, the Nef-induced Lck compartment contains signaling-competent forms (phosphorylated on key Tyr residues) of Lck and some of its downstream effectors, TCRζ, ZAP70, SLP76, and Vav1, avoiding the proximal LAT adaptor. Importantly, Nef-induced concentration of signaling molecules was concomitant with the upregulation of several early and late T cell activation genes. Moreover, preventing the concentration of the Nef-induced Lck compartment by depleting the Rab11 effector FIP3 counteracted Nef-induced gene expression upregulation. In addition, Nef extensively sequesters Rac1 and downregulates Rac1-dependent actin cytoskeleton remodeling, thus reducing T cell spreading. Therefore, by modifying their endosomal traffic, Nef hijacks signaling and actin cytoskeleton regulators to dually modulate their functional outputs. Our data shed new light into the molecular mechanisms that modify T cell physiology during HIV-1 infection.
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Affiliation(s)
- Iratxe Del Río-Iñiguez
- Lymphocyte Cell Biology Unit, Department of Immunology, Institut Pasteur, 75724 Paris, France.,INSERM U1221, 75015 Paris, France; and.,Collège Doctoral, Sorbonne Université, 75014 Paris, France
| | - Elena Vázquez-Chávez
- Lymphocyte Cell Biology Unit, Department of Immunology, Institut Pasteur, 75724 Paris, France.,INSERM U1221, 75015 Paris, France; and
| | - Céline Cuche
- Lymphocyte Cell Biology Unit, Department of Immunology, Institut Pasteur, 75724 Paris, France.,INSERM U1221, 75015 Paris, France; and
| | - Vincenzo Di Bartolo
- Lymphocyte Cell Biology Unit, Department of Immunology, Institut Pasteur, 75724 Paris, France.,INSERM U1221, 75015 Paris, France; and
| | - Jérôme Bouchet
- Lymphocyte Cell Biology Unit, Department of Immunology, Institut Pasteur, 75724 Paris, France; .,INSERM U1221, 75015 Paris, France; and
| | - Andrés Alcover
- Lymphocyte Cell Biology Unit, Department of Immunology, Institut Pasteur, 75724 Paris, France; .,INSERM U1221, 75015 Paris, France; and
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8
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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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9
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Silva JG, Martins NP, Henriques R, Soares H. HIV-1 Nef Impairs the Formation of Calcium Membrane Territories Controlling the Signaling Nanoarchitecture at the Immunological Synapse. THE JOURNAL OF IMMUNOLOGY 2016; 197:4042-4052. [PMID: 27798165 DOI: 10.4049/jimmunol.1601132] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 09/16/2016] [Indexed: 12/21/2022]
Abstract
The ability of HIV-1 to replicate and to establish long-term reservoirs is strongly influenced by T cell activation. Through the use of membrane-tethered, genetically encoded calcium (Ca2+) indicators, we were able to detect for the first time, to our knowledge, the formation of Ca2+ territories and determine their role in coordinating the functional signaling nanostructure of the synaptic membrane. Consequently, we report a previously unknown immune subversion mechanism involving HIV-1 exploitation, through its Nef accessory protein, of the interconnectivity among three evolutionarily conserved cellular processes: vesicle traffic, signaling compartmentalization, and the second messenger Ca2+ We found that HIV-1 Nef specifically associates with the traffic regulators MAL and Rab11b compelling the vesicular accumulation of Lck. Through its association with MAL and Rab11b, Nef co-opts Lck switchlike function driving the formation Ca2+ membrane territories, which, in turn, control the fusion of LAT-transporting Rab27 and Rab37 vesicles and the formation of LAT nanoclusters at the immunological synapse. Consequently, HIV-1 Nef disengages TCR triggering from the generation of p-LAT and p-SLP nanoclusters driving TCR signal amplification and diversification. Altogether our results indicate that HIV-1 exploits the interconnectivity among vesicle traffic, Ca2+ membrane territories, and signaling nanoclusters to modulate T cell signaling and function.
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Affiliation(s)
- Joana G Silva
- Immunobiology and Pathogenesis Group, Chronic Diseases Research Center, NOVA Medical School, NOVA University of Lisbon, 1150-082 Lisbon, Portugal
| | - Nuno P Martins
- Unit of Imaging and Cytometry, Gulbenkian Institute for Science, 2780-156 Oeiras, Portugal
| | - Ricardo Henriques
- Quantitative Imaging and Nanobiophysics Group, Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, United Kingdom; and.,Department of Cell and Developmental Biology, University College London, London WC1E 6BT, United Kingdom
| | - Helena Soares
- Immunobiology and Pathogenesis Group, Chronic Diseases Research Center, NOVA Medical School, NOVA University of Lisbon, 1150-082 Lisbon, Portugal;
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10
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Martínez-Bonet M, Palladino C, Briz V, Rudolph JM, Fackler OT, Relloso M, Muñoz-Fernandez MA, Madrid R. A Conserved GPG-Motif in the HIV-1 Nef Core Is Required for Principal Nef-Activities. PLoS One 2015; 10:e0145239. [PMID: 26700863 PMCID: PMC4689412 DOI: 10.1371/journal.pone.0145239] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2015] [Accepted: 11/30/2015] [Indexed: 12/26/2022] Open
Abstract
To find out new determinants required for Nef activity we performed a functional alanine scanning analysis along a discrete but highly conserved region at the core of HIV-1 Nef. We identified the GPG-motif, located at the 121–137 region of HIV-1 NL4.3 Nef, as a novel protein signature strictly required for the p56Lck dependent Nef-induced CD4-downregulation in T-cells. Since the Nef-GPG motif was dispensable for CD4-downregulation in HeLa-CD4 cells, Nef/AP-1 interaction and Nef-dependent effects on Tf-R trafficking, the observed effects on CD4 downregulation cannot be attributed to structure constraints or to alterations on general protein trafficking. Besides, we found that the GPG-motif was also required for Nef-dependent inhibition of ring actin re-organization upon TCR triggering and MHCI downregulation, suggesting that the GPG-motif could actively cooperate with the Nef PxxP motif for these HIV-1 Nef-related effects. Finally, we observed that the Nef-GPG motif was required for optimal infectivity of those viruses produced in T-cells. According to these findings, we propose the conserved GPG-motif in HIV-1 Nef as functional region required for HIV-1 infectivity and therefore with a potential interest for the interference of Nef activity during HIV-1 infection.
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Affiliation(s)
- Marta Martínez-Bonet
- Laboratorio de Inmunobiología Molecular, Instituto de Investigación Biomédica Gregorio Marañón (IISGM), 28007 Madrid, Spain
| | - Claudia Palladino
- Laboratorio de Inmunobiología Molecular, Instituto de Investigación Biomédica Gregorio Marañón (IISGM), 28007 Madrid, Spain
| | - Veronica Briz
- Laboratorio de Inmunobiología Molecular, Instituto de Investigación Biomédica Gregorio Marañón (IISGM), 28007 Madrid, Spain
| | - Jochen M. Rudolph
- Department of Infectious Diseases, Integrative Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Oliver T. Fackler
- Department of Infectious Diseases, Integrative Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Miguel Relloso
- Laboratorio de Inmunobiología Molecular, Instituto de Investigación Biomédica Gregorio Marañón (IISGM), 28007 Madrid, Spain
| | - Maria Angeles Muñoz-Fernandez
- Laboratorio de Inmunobiología Molecular, Instituto de Investigación Biomédica Gregorio Marañón (IISGM), 28007 Madrid, Spain
| | - Ricardo Madrid
- Departament of Virology. Centro de Biología Molecular Severo Ochoa, CSIC/UAM, Madrid, Spain
- * E-mail:
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11
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Kenney SP, Meng XJ. An SH3 binding motif within the nucleocapsid protein of porcine reproductive and respiratory syndrome virus interacts with the host cellular signaling proteins STAMI, TXK, Fyn, Hck, and cortactin. Virus Res 2015; 204:31-9. [PMID: 25882913 DOI: 10.1016/j.virusres.2015.04.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 04/02/2015] [Accepted: 04/05/2015] [Indexed: 01/15/2023]
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) causes an economically important global swine disease, and has a complicated virus-host immunomodulation that often leads to a weak Th2 immune response and viral persistence. In this study, we identified a Src homology 3 (SH3) binding motif, PxxPxxP, that is conserved within the N protein of PRRSV strains. Subsequently, we identified five host cellular proteins [signal transducing adaptor molecule (STAM)I, TXK tyrosine kinase (TXK), protein tyrosine kinase fyn (Fyn), hematopoietic cell kinase (Hck), and cortactin] that interact with this SH3 motif. We demonstrated that binding of SH3 proteins with PRRSV N protein depends on at least one intact PxxP motif as disruption of P53 within the motif significantly reduced interaction of each of the 5 proteins. The first PxxP motif appears to be more important for STAMI-N protein interactions whereas the second PxxP motif was more important for Hck interaction. Both STAMI and Hck interactions with PRRSV N protein required an unhindered C-terminal domain as the interaction was only observed with STAMI and Hck proteins with N-terminal but not C-terminal fluorescent tags. We showed that the P56 residue within the SH3 motif is critical for virus lifecycle as mutation resulted in a loss of virus infectivity, however the P50 and P53 mutations did not abolish virus infectivity suggesting that these highly conserved proline residues within the SH3 motif may provide a selective growth advantage through interactions with the host rather than a vital functional element. These results have important implications in understanding PRRSV-host interactions.
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Affiliation(s)
- Scott P Kenney
- Center for Molecular Medicine and Infectious Diseases, Department of Biomedical Sciences and Pathobiology, College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | - Xiang-Jin Meng
- Center for Molecular Medicine and Infectious Diseases, Department of Biomedical Sciences and Pathobiology, College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States.
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12
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HIV-1 Nef and Vpu are functionally redundant broad-spectrum modulators of cell surface receptors, including tetraspanins. J Virol 2014; 88:14241-57. [PMID: 25275127 DOI: 10.1128/jvi.02333-14] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
UNLABELLED HIV-1 Nef and Vpu are thought to optimize virus replication in the infected host, at least in part via their ability to interfere with vesicular host cell trafficking. Despite the use of distinct molecular mechanisms, Nef and Vpu share specificity for some molecules such as CD4 and major histocompatibility complex class I (MHC-I), while disruption of intracellular transport of the host cell restriction factor CD317/tetherin represents a specialized activity of Vpu not exerted by HIV-1 Nef. To establish a profile of host cell receptors whose intracellular transport is affected by Nef, Vpu, or both, we comprehensively analyzed the effect of these accessory viral proteins on cell surface receptor levels on A3.01 T lymphocytes. Thirty-six out of 105 detectable receptors were significantly downregulated by HIV-1 Nef, revealing a previously unappreciated scope with which HIV-1 Nef remodels the cell surface of infected cells. Remarkably, the effects of HIV-1 Vpu on host cell receptor exposure largely matched those of HIV-1 Nef in breadth and specificity (32 of 105, all also targeted by Nef), even though the magnitude was generally less pronounced. Of particular note, cell surface exposure of all members of the tetraspanin (TSPAN) protein family analyzed was reduced by both Nef and Vpu, and the viral proteins triggered the enrichment of TSPANs in a perinuclear area of the cell. While Vpu displayed significant colocalization and physical association with TSPANs, interactions of Nef with TSPANs were less robust. TSPANs thus emerge as a major target of deregulation in host cell vesicular transport by HIV-1 Nef and Vpu. The conservation of this activity in two independent accessory proteins suggests its importance for the spread of HIV-1 in the infected host. IMPORTANCE In this paper, we define that HIV-1 Nef and Vpu display a surprising functional overlap and affect the cell surface exposure of a previously unexpected breadth of cellular receptors. Our analyses furthermore identify the tetraspanin protein family as a previously unrecognized target of Nef and Vpu activity. These findings have implications for the interpretation of effects detected for these accessory gene products on individual host cell receptors and illustrate the coevolution of Nef and Vpu function.
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13
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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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14
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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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15
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Tschulena U, Sanzenbacher R, Mühlebach MD, Berger A, Münch J, Schindler M, Kirchhoff F, Plesker R, Coulibaly C, Panitz S, Prüfer S, Muckenfuss H, Hamdorf M, Schweizer M, Cichutek K, Flory E. Mutation of a diacidic motif in SIV-PBj Nef impairs T-cell activation and enteropathic disease. Retrovirology 2011; 8:14. [PMID: 21366921 PMCID: PMC3060844 DOI: 10.1186/1742-4690-8-14] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Accepted: 03/02/2011] [Indexed: 11/10/2022] Open
Abstract
Background The non-pathogenic course of SIV infection in its natural host is characterized by robust viral replication in the absence of chronic immune activation and T cell proliferation. In contrast, acutely lethal enteropathic SIVsmm strain PBj induces a strong immune activation and causes a severe acute and lethal disease in pig-tailed macaques after cross-species transmission. One important pathogenicity factor of the PBj virus is the PBj-Nef protein, which contains a conserved diacidic motif and, unusually, an immunoreceptor tyrosine-based activation motif (ITAM). Results Mutation of the diacidic motif in the Nef protein of the SIVsmmPBj abolishes the acute phenotype of this virus. In vitro, wild-type and mutant PBj (PBj-Nef202/203GG) viruses replicated to similar levels in macaque PBMCs, but PBj-Nef202/203GG no longer triggers ERK mitogen-activated protein (MAP) kinase pathway including an alteration of a Nef-associated Raf-1/ERK-2 multiprotein signaling complex. Moreover, stimulation of IL-2 and down-modulation of CD4 and CD28 were impaired in the mutant virus. Pig-tailed macaques infected with PBj-Nef202/203GG did not show enteropathic complications and lethality as observed with wild-type PBj virus, despite efficient replication of both viruses in vivo. Furthermore, PBj-Nef202/203GG infected animals revealed reduced T-cell activation in periphery lymphoid organs and no detectable induction of IL-2 and IL-6. Conclusions In sum, we report here that mutation of the diacidic motif in the PBj-Nef protein abolishes disease progression in pig-tailed macaques despite efficient replication. These data suggest that alterations in the ability of a lentivirus to promote T cell activation and proliferation can have a dramatic impact on its pathogenic potential.
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Affiliation(s)
- Ulrich Tschulena
- Division of Medical Biotechnology, Paul-Ehrlich-Institut, Langen, Germany.
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16
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Chrobak P, Simard MC, Bouchard N, Ndolo TM, Guertin J, Hanna Z, Dave V, Jolicoeur P. HIV-1 Nef Disrupts Maturation of CD4+T Cells through CD4/Lck Modulation. THE JOURNAL OF IMMUNOLOGY 2010; 185:3948-59. [DOI: 10.4049/jimmunol.1001064] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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17
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Poe JA, Smithgall TE. HIV-1 Nef dimerization is required for Nef-mediated receptor downregulation and viral replication. J Mol Biol 2009; 394:329-42. [PMID: 19781555 DOI: 10.1016/j.jmb.2009.09.047] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2009] [Revised: 09/15/2009] [Accepted: 09/17/2009] [Indexed: 10/20/2022]
Abstract
Nef, a human immunodeficiency virus type 1 (HIV-1) accessory factor capable of interaction with a diverse array of host cell signaling molecules, is essential for high-titer HIV replication and AIDS progression. Previous biochemical and structural studies have suggested that Nef may form homodimers and higher-order oligomers in HIV-infected cells, which may be required for both immune and viral receptor downregulation as well as viral replication. Using bimolecular fluorescence complementation, we provide the first direct evidence for Nef dimers within HIV host cells and identify the structural requirements for dimerization in vivo. Bimolecular fluorescence complementation analysis shows that the multiple hydrophobic and electrostatic interactions found within the dimerization interface of the Nef X-ray crystal structure are essential for dimerization in cells. Nef dimers localized to the plasma membrane as well as the trans-Golgi network, two subcellular localizations essential for Nef function. Mutations in the Nef dimerization interface dramatically reduced both Nef-induced CD4 downregulation and HIV replication. Viruses expressing dimerization-defective Nef mutants were disabled to the same extent as HIV that fails to express Nef in terms of replication. These results identify the Nef dimerization region as a potential molecular target for antiretroviral drug discovery.
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Affiliation(s)
- Jerrod A Poe
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, E1240 Biomedical Science Tower, Pittsburgh, PA 15261, USA
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18
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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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19
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Witte V, Laffert B, Gintschel P, Krautkrämer E, Blume K, Fackler OT, Baur AS. Induction of HIV Transcription by Nef Involves Lck Activation and Protein Kinase Cθ Raft Recruitment Leading to Activation of ERK1/2 but Not NFκB. THE JOURNAL OF IMMUNOLOGY 2008; 181:8425-32. [DOI: 10.4049/jimmunol.181.12.8425] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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20
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Emaduddin M, Edelmann MJ, Kessler BM, Feller SM. Odin (ANKS1A) is a Src family kinase target in colorectal cancer cells. Cell Commun Signal 2008; 6:7. [PMID: 18844995 PMCID: PMC2584000 DOI: 10.1186/1478-811x-6-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2008] [Accepted: 10/09/2008] [Indexed: 11/25/2022] Open
Abstract
Background Src family kinases (SFK) are implicated in the development of some colorectal cancers (CRC). One SFK member, Lck, is not detectable in normal colonic epithelium, but becomes aberrantly expressed in a subset of CRCs. Although SFK have been extensively studied in fibroblasts and different types of immune cells, their physical and functional targets in many epithelial cancers remain poorly characterised. Results 64 CRC cell lines were tested for expression of Lck. SW620 CRC cells, which express high levels of Lck and also contain high basal levels of tyrosine phosphorylated (pY) proteins, were then analysed to identify novel SFK targets. Since SH2 domains of SFK are known to often bind substrates after phosphorylation by the kinase domain, the LckSH2 was compared with 14 other SH2s for suitability as affinity chromatography reagent. Mass spectrometric analyses of LckSH2-purified pY proteins subsequently identified several proteins readily known as SFK kinase substrates, including cortactin, Tom1L1 (SRCASM), GIT1, vimentin and AFAP1L2 (XB130). Additional proteins previously reported as substrates of other tyrosine kinase were also detected, including the EGF and PDGF receptor target Odin. Odin was further analysed and found to contain substantially less pY upon inhibition of SFK activity in SW620 cells, indicating that it is a formerly unknown SFK target in CRC cells. Conclusion Rapid identification of known and novel SFK targets in CRC cells is feasible with SH2 domain affinity chromatography. The elucidation of new SFK targets like Odin in epithelial cancer cells is expected to lead to novel insight into cancer cell signalling mechanisms and may also serve to indicate new biomarkers for monitoring tumor cell responses to drug treatments.
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Affiliation(s)
- Muhammad Emaduddin
- Cell Signalling Group, Department of Molecular Oncology, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford University, Headley Way, Oxford OX3 9DS, UK.
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21
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22
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Wolf D, Giese SI, Witte V, Krautkrämer E, Trapp S, Sass G, Haller C, Blume K, Fackler OT, Baur AS. Novel (n)PKC kinases phosphorylate Nef for increased HIV transcription, replication and perinuclear targeting. Virology 2007; 370:45-54. [PMID: 17904606 DOI: 10.1016/j.virol.2007.08.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2007] [Revised: 05/28/2007] [Accepted: 08/08/2007] [Indexed: 10/22/2022]
Abstract
The N-terminus of the human immunodeficiency virus (HIV) pathogenicity factor Nef associates with a protein complex (NAKC for Nef-associated kinase complex) that contains at least two kinases: the tyrosine kinase Lck and a serine kinase activity which was found to phosphorylate Lck and the Nef N-terminus. Here we show that this serine kinase activity is mediated by members of the novel Protein Kinase C (nPKC) subfamily, PKCdelta and theta. Association with the Nef N-terminus was sufficient to activate PKC leading to phosphorylation of Nef in vitro on a conserved serine residue at position 6. Mutation of serine 6 or coexpression of a transdominant negative PKC mutant significantly reduced Nef-stimulated HIV transcription and replication in resting PBMC. When analyzing the molecular mechanisms, we found that mutating serine 6 moderately affected myristoylation of Nef and its association with Pak2 activity, whereas CD4 downmodulation was not inhibited. More interestingly, this mutation abolished the typical perinuclear localization of Nef in T cells. We conclude that the activation of nPKCs by Nef is required to increase viral replication/infectivity and direct the subcellular localization of Nef.
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Affiliation(s)
- Dietlinde Wolf
- University of Miami, Miller School of Medicine, Department of Microbiology and Immunology, BCRI 739, Miami, FL 33136, USA
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23
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Fukumoto R, Dundr M, Nicot C, Adams A, Valeri VW, Samelson LE, Franchini G. Inhibition of T-cell receptor signal transduction and viral expression by the linker for activation of T cells-interacting p12(I) protein of human T-cell leukemia/lymphoma virus type 1. J Virol 2007; 81:9088-99. [PMID: 17582004 PMCID: PMC1951423 DOI: 10.1128/jvi.02703-06] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The p12(I) protein of human T-cell leukemia/lymphoma virus type 1 (HTLV-1) is a small oncoprotein that increases calcium release following protein kinase C activation by phorbol myristate acetate, and importantly, this effect is linker for activation of T cells (LAT) independent. Here, we demonstrate that p12(I) inhibits the phosphorylation of LAT, Vav, and phospholipase C-gamma 1 and decreases NFAT (nuclear factor of activated T cells) activation upon engagement of the T-cell receptor (TCR) with anti-CD3 antibody. Furthermore, we demonstrate that p12(I) localizes to membrane lipid rafts and, upon engagement of the TCR, relocalizes to the interface between T cells and antigen-presenting cells, defined as the immunological synapse. A p12(I) knockout molecular clone of HTLV-1 expresses more virus upon antigen stimulation than the isogenic wild type, suggesting that, by decreasing T-cell responsiveness, p12(I) curtails viral expression. Thus, p12(I) has contrasting effects on TCR signaling: it down-regulates TCR in a LAT-dependent manner on one hand, and on the other, it increases calcium release in a LAT-independent manner. The negative regulation of T-cell activation by p12(I) may have evolved to minimize immune recognition of infected CD4(+) T cells, to impair the function of infected cytotoxic CD8(+) T cells, and to favor viral persistence in the infected host.
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Affiliation(s)
- Risaku Fukumoto
- Animal Models and Retroviral Vaccines Section, National Cancer Institute, NIH, Bethesda, MD 20892-5065, USA
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24
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Trible RP, Emert-Sedlak L, Smithgall TE. HIV-1 Nef selectively activates Src family kinases Hck, Lyn, and c-Src through direct SH3 domain interaction. J Biol Chem 2006; 281:27029-38. [PMID: 16849330 PMCID: PMC2892265 DOI: 10.1074/jbc.m601128200] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nef is an HIV-1 virulence factor that promotes viral pathogenicity by altering host cell signaling pathways. Nef binds several members of the Src kinase family, and these interactions have been implicated in the pathogenesis of HIV/AIDS. However, the direct effect of Nef interaction on Src family kinase (SFK) regulation and activity has not been systematically addressed. We explored this issue using Saccharomyces cerevisiae, a well defined model system for the study of SFK regulation. Previous studies have shown that ectopic expression of c-Src arrests yeast cell growth in a kinase-dependent manner. We expressed Fgr, Fyn, Hck, Lck, Lyn, and Yes as well as c-Src in yeast and found that each kinase was active and induced growth suppression. Co-expression of the negative regulatory kinase Csk suppressed SFK activity and reversed the growth-inhibitory effect. We then co-expressed each SFK with HIV-1 Nef in the presence of Csk. Nef strongly activated Hck, Lyn, and c-Src but did not detectably affect Fgr, Fyn, Lck, or Yes. Mutagenesis of the Nef PXXP motif essential for SH3 domain binding greatly reduced the effect of Nef on Hck, Lyn, and c-Src, suggesting that Nef activates these Src family members through allosteric displacement of intramolecular SH3-linker interactions. These data show that Nef selectively activates Hck, Lyn, and c-Src among SFKs, identifying these kinases as proximal effectors of Nef signaling and potential targets for anti-HIV drug discovery.
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Affiliation(s)
| | | | - Thomas E. Smithgall
- To whom correspondence should be addressed: Dept. of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, E1240 Biomedical Science Tower, Pittsburgh, PA 15261. Tel.: 412-648-9495; Fax: 412-624-1401;
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25
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Thoulouze MI, Sol-Foulon N, Blanchet F, Dautry-Varsat A, Schwartz O, Alcover A. Human immunodeficiency virus type-1 infection impairs the formation of the immunological synapse. Immunity 2006; 24:547-61. [PMID: 16713973 DOI: 10.1016/j.immuni.2006.02.016] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2005] [Revised: 02/08/2006] [Accepted: 02/27/2006] [Indexed: 10/24/2022]
Abstract
HIV-1-infected lymphocytes improperly respond to T cell antigen receptor (TCR) stimulation. To document this phenomenon, we studied the capacity of HIV-1-infected lymphocytes to form immunological synapses. We show here that HIV-1-infected T cells poorly conjugated with antigen-presenting cells, and when they formed conjugates, the synapses were abnormal. TCR and Lck accumulated in the recycling endosomal compartment, and their clustering at the synapse was severely reduced. These phenomena were, to a large extent, caused by Nef, a viral protein affecting intracellular trafficking and signaling pathways. Concomitantly, in HIV-infected cells, tyrosine phosphorylation at the synapse and the patterns of tyrosine phosphorylated proteins were disturbed in a Nef-dependent manner. These findings underscore the importance of Lck and TCR endosomal trafficking in synapse formation and early T cell signaling. Alteration of endocytic and signaling networks at the immunological synapse likely impacts the function and fate of HIV-1-infected cells.
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Affiliation(s)
- Maria Isabel Thoulouze
- Unité de Biologie Cellulaire des Lymphocytes, Centre National de la Recherche Scientifique Unité de Recherche Associée-1930, Institut Pasteur, 25-28 rue Dr Roux, 75724 Paris Cedex 15, France
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26
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Caples MJ, Clements JE, Barber SA. Protein kinase CK2 phosphorylates the Nef protein from a neurovirulent simian immunodeficiency virus. Virology 2006; 348:156-64. [PMID: 16448682 DOI: 10.1016/j.virol.2005.12.028] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2005] [Revised: 10/21/2005] [Accepted: 12/22/2005] [Indexed: 10/25/2022]
Abstract
The Nef protein of Human Immunodeficiency Virus (HIV) and Simian Immunodeficiency Virus (SIV) is a pluripotent accessory protein that plays a critical role in disease progression. One analogous characteristic of Nef proteins from SIV and HIV is the ability to associate with cellular kinases. We have previously reported that the Nef protein from a macrophage-tropic neurovirulent SIV clone, SIV/17E-Fr, is associated with an unknown kinase activity that is distinct from the p21-associated kinase that interacts with SIVmac239 Nef. Using site-directed mutagenesis and kinase-specific inhibitors, we have identified this kinase as the ubiquitous serine/threonine kinase, protein kinase CK2.
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Affiliation(s)
- Matthew J Caples
- Department of Comparative Medicine, Johns Hopkins University School of Medicine, 733 N. Broadway St., Broadway Research Building 831, Baltimore, MD 21205, USA
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27
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Hel Z, Tsai WP, Tryniszewska E, Nacsa J, Markham PD, Lewis MG, Pavlakis GN, Felber BK, Tartaglia J, Franchini G. Improved vaccine protection from simian AIDS by the addition of nonstructural simian immunodeficiency virus genes. THE JOURNAL OF IMMUNOLOGY 2006; 176:85-96. [PMID: 16365399 DOI: 10.4049/jimmunol.176.1.85] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
An HIV-1 vaccine able to induce broad CD4+ and CD8+ T cell responses may provide long-term control of viral replication. In this study we directly assess the relative benefit of immunization with vaccines expressing three structural Ags (Gag, Pol, and Env), three early regulatory proteins (Rev, Tat, and Nef), or a complex vaccine expressing all six Ags. The simultaneous administration of all six Ags during vaccination resulted in Ag competition manifested by a relative reduction of CD8+ T cell and lymphoproliferative responses to individual Ags. Despite the Ag competition, vaccination with all six Ags resulted in a delay in the onset and a decrease in the extent of acute viremia after mucosal challenge exposure to highly pathogenic SIV(mac251). Reduced levels of acute viremia correlated with lower post-set point viremia and long-term control of infection. In immunized animals, virus-specific CD4+ T cell and lymphoproliferative responses were preserved during acute viremia, and the maintenance of these responses predicted the long-term virological outcome. Taken together, these results suggest that the breadth of the immune response is probably more important than high frequency responses to a limited number of epitopes. These data provide the first clear evidence of the importance of nonstructural HIV Ags as components of an HIV-1 vaccine.
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Affiliation(s)
- Zdenek Hel
- Animal Models and Retroviral Vaccines Section, National Cancer Institute, Bethesda, MD 20892, USA
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Gilbert C, Bergeron M, Méthot S, Giguère JF, Tremblay MJ. Statins Could Be Used to Control Replication of Some Viruses, Including HIV-1. Viral Immunol 2005; 18:474-89. [PMID: 16212526 DOI: 10.1089/vim.2005.18.474] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Statins are mainly known for their plasma cholesterol-lowering properties and are widely used for the prevention of cardiovascular diseases. They however also exert pleiotropic effects through a variety of mechanisms, among which several immunosuppressive effects that are unrelated to their cholesterol-lowering activity. Interestingly, there has been recent evidence of antiviral effects, including preliminary studies on the efficacy of statins against HIV-1. This paper more particularly focuses on the specific inhibition of the binding of leukocyte function-associated antigen-1 (LFA-1) to intercellular adhesion molecule (ICAM-1) by statins, independently of the inhibition of HMGCoA reductase. Targeting the statin-binding site within LFA-1 or regulating LFA-1 affinity by inhibiting prenylation of the small GTPases could prove useful to treat inflammatory, autoimmune diseases and possibly viral infections, including HIV-1.
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Affiliation(s)
- Caroline Gilbert
- Research Center in Infectious Diseases, CHUL Research Center, Laval University, 2705 Laurier Boulevard, Quebec, Canada G1V 4G2
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29
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Yang P, Henderson AJ. Nef enhances c-Cbl phosphorylation in HIV-infected CD4+ T lymphocytes. Virology 2005; 336:219-28. [PMID: 15892963 DOI: 10.1016/j.virol.2005.03.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2004] [Revised: 12/16/2004] [Accepted: 03/21/2005] [Indexed: 10/25/2022]
Abstract
The multifunctional HIV-1 protein Nef possesses several motifs that interact with signaling molecules in infected T cells. In order to determine whether Nef influences T cell activation, cells were infected with Nef-positive and Nef-negative clones of HIV. CD28 expression and changes in tyrosine phosphorylation were monitored. We observed no Nef-dependent changes in CD28 expression or function. However, infection with Nef-positive virus led to changes in tyrosine phosphorylation. This Nef-induced phosphorylation was observed in unstimulated cells, and c-Cbl was identified as one of the proteins whose phosphorylation was upregulated by Nef. Furthermore, Lck is required for Nef-mediated c-Cbl tyrosine phosphorylation. These results suggest that Nef modifies T cell signaling in the absence of T cell receptor engagement and co-stimulation.
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Affiliation(s)
- Polung Yang
- Integrated Bioscience Graduate Program in Immunobiology, Department of Veterinary Science, Immunology Research Laboratories, 115 Henning Building, Pennsylvania State University, University Park, PA 16802, USA
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30
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Coleman SH, Day JR, Guatelli JC. The HIV-1 Nef protein as a target for antiretroviral therapy. Expert Opin Ther Targets 2005; 5:1-22. [PMID: 15992165 DOI: 10.1517/14728222.5.1.1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
HIV-1 Nef is a peripheral membrane protein that affects both signal transduction and membrane trafficking in infected cells. Alterations in these cellular processes enhance the efficiency of viral replication and the pathogenesis of AIDS in vivo. The precise mechanisms by which Nef functions are not fully elucidated. Nef is not an enzyme but appears to act as a linker molecule, mediating a variety of protein-protein interactions. Structural, biochemical and mutational data have allowed tentative identification of the key interactive surfaces on Nef, their cellular partners and their roles in Nef activity. Nef contains an SH3-binding surface through which it can interact with cellular Src-family tyrosine kinases and/or activator molecules for small GTPases involved in signal transduction. This SH3-binding surface is important for the ability of Nef to facilitate the activation of host T-lymphocytes, a process which renders the cells more permissive for viral replication. Nef also contains two relatively unstructured, solvent-exposed loops, through which it interacts with the cellular proteins that coat vesicles involved in membrane trafficking. These surfaces are important for Nef-mediated alterations in the subcellular distribution of transmembrane proteins, a process which causes diverse effects, including the assembly of maximally infectious viral particles and viral evasion of the host immune system. These data provide precise molecular targets within the Nef protein. Molecules that bind these interactive surfaces are predicted to inhibit Nef activity and provide the basis for novel chemotherapeutic agents for the treatment of HIV-infection.
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Affiliation(s)
- S H Coleman
- Department of Medicine, University of California San Diego, La Jolla 92093-0679, USA
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31
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Brown A, Gartner S, Kawano T, Benoit N, Cheng-Mayer C. HLA-A2 down-regulation on primary human macrophages infected with an M-tropic EGFP-tagged HIV-1 reporter virus. J Leukoc Biol 2005; 78:675-85. [PMID: 16000390 DOI: 10.1189/jlb.0505237] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Multiple mechanisms are used by the human immunodeficiency virus type 1 (HIV-1) to interfere with host-cell immune effector functions. The 27-kD Nef protein has been shown to down-modulate specific genes of the major histocompatibility complex class I (MHC-I) on the surface of infected primary T cells, facilitating their escape from lysis by cytolytic T lymphocytes. Macrophages, as the other major immune cell type targeted by the virus, also contribute to the transmission, persistence, and pathogenesis of HIV-1. Yet, whether Nef modulates MHC-I expression on HIV-infected primary macrophages remains unclear. Currently available infectious HIV-1 molecular clones, which express a reporter gene, only infect T cells and/or do not express Nef. To overcome these limitations, we generated macrophage-tropic green fluorescent protein (GFP)-tagged HIV-1 viruses, which express the complete viral genome, and used these to assess the expression of human leukocyte antigen (HLA)-A2 on the surface of productively infected macrophages. The reporter viral genomes were replication-competent and stable, as Nef, p24 antigen, and GFP expression could be detected by immunostaining of infected, monocyte-derived macrophages (MDM) after more than 2 months postinfection. Fluorescence-activated cell sorter analyses of infected macrophages and T cells revealed that although wild-type reporter virus infection induced a statistically significant decrease in the density of surface HLA-A2, down-regulation of HLA-A2 was not seen in cells infected with reporter viruses encoding a frameshift or a single point mutation in Nef at prolines 74P and P80. The impact of Nef on HLA-A2 surface expression in MDM was also confirmed by confocal microscopy. These results suggest that the mechanisms of HLA-A2 down-modulation are similar in primary T cells and macrophages.
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Affiliation(s)
- Amanda Brown
- Department of Neurology, Meyer 6-181, 600 North Wolfe Street, Baltimore, MD 21287, USA.
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32
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Briese L, Preusser A, Willbold D. Mapping the binding site of full length HIV-1 Nef on human Lck SH3 by NMR spectroscopy. J Biomed Sci 2005; 12:451-6. [PMID: 15976924 DOI: 10.1007/s11373-005-6797-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2005] [Accepted: 04/27/2005] [Indexed: 10/25/2022] Open
Abstract
The Nef protein of human immunodeficiency virus type 1 (HIV-1) is known to directly bind to the SH3 domain of human lymphocyte specific kinase (Lck) via a proline-rich region located in the amino terminal part of Nef. To address the question whether Nef binding to Lck SH3 involves residues outside the typical poly-proline peptide binding site and whether the Lck unique domain is involved in Nef-Lck interaction, we studied the direct interaction between both molecules using recombinant full-length HIV-1 Nef protein on one side and recombinantly expressed and uniformly 15N-isotope labeled Lck protein comprising unique and SH3 domains on the other side. Applying nuclear magnetic resonance spectroscopy we could show that only residues of Lck SH3, that are typically involved in binding poly-proline peptides, are affected by Nef binding. Further, for the first time we could rule out that residues of Lck unique domain are involved in binding to full length Nef protein. Thus, interactions of Lck unique domain to cellular partners e.g. CD4 or CD8, are not necessarily competitive with Lck binding to HIV-1 Nef.
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Affiliation(s)
- Lars Briese
- Institut für Molekulare Biotechnologie, 07745, Jena, Germany
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33
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Biomedical Vignette. J Biomed Sci 2005. [DOI: 10.1007/s11373-005-8617-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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34
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Matsubara M, Jing T, Kawamura K, Shimojo N, Titani K, Hashimoto K, Hayashi N. Myristoyl moiety of HIV Nef is involved in regulation of the interaction with calmodulin in vivo. Protein Sci 2005; 14:494-503. [PMID: 15632291 PMCID: PMC2253426 DOI: 10.1110/ps.04969605] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Human immunodeficiency virus Nef is a myristoylated protein expressed early in infection by HIV. In addition to the well known down-regulation of the cell surface receptors CD4 and MHCI, Nef is able to alter T-cell signaling pathways. The ability to alter the cellular signaling pathways suggests that Nef can associate with signaling proteins. In the present report, we show that Nef can interact with calmodulin, the major intracellular receptor for calcium. Coimmunoprecipitation analyses with lysates from the NIH3T3 cell line constitutively expressing the native HIV-1 Nef protein revealed the presence of a stable Nef-calmodulin complex. When lysates from NIH3T3 cells were incubated with calmodulin-agarose beads in the presence of CaCl(2) or EGTA, calcium ion drastically enhanced the interaction between Nef and calmodulin, suggesting that the binding is under the influence of Ca(2+) signaling. Glutathione S-transferase-Nef fusion protein bound directly to calmodulin with high affinity. Using synthetic peptides based on the N-terminal sequence of Nef, we determined that within a 20-amino-acid N-terminal basic domain was sufficient for calmodulin binding. Furthermore, the myristoylated peptide bound to calmodulin with higher affinity than nonmyris-toylated form. Thus, the N-terminal myristoylation domain of Nef plays an important role in interacting with calmodulin. This domain is highly conserved in several HIV-1 Nef variants and resembles the N-terminal domain of NAP-22/CAP23, a myristoylated calmodulin-binder. These results for the interaction between HIV Nef and calmodulin in the cells suggested that the Nef might interfere with intracellular Ca(2+) signaling through calmodulin-mediated interactions in infected cells.
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Affiliation(s)
- Mamoru Matsubara
- Division of Biomedical Polymer Science, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi 470-1192, Japan
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35
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Hanna Z, Priceputu E, Kay DG, Poudrier J, Chrobak P, Jolicoeur P. In vivo mutational analysis of the N-terminal region of HIV-1 Nef reveals critical motifs for the development of an AIDS-like disease in CD4C/HIV transgenic mice. Virology 2004; 327:273-86. [PMID: 15351215 DOI: 10.1016/j.virol.2004.06.028] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2004] [Accepted: 06/11/2004] [Indexed: 10/26/2022]
Abstract
HIV-1 Nef is a critical determinant of pathogenicity in humans and transgenic (Tg) mice. To gain a better understanding of the molecular mechanisms by which Nef induces an AIDS-like disease in Tg mice, a mutational analysis of the N-terminal domain, involved in anchoring Nef to the plasma membrane, was carried out. The pathogenic effects of these Nef mutant alleles were evaluated in Tg mice by FACS analysis and by histopathological assessment. Mutation of the myristoylation site (G2A) completely abrogated the development of the AIDS-like organ disease in Tg mice, although partial downregulation of the CD4 cell surface protein and depletion of peripheral CD4+ T-cells, but not of CD4(+)CD8+ thymocytes, still occurred. Despite that, the peripheral CD4+ T cells expressing Nef(G2A) show normal spontaneous proliferation in vivo or after stimulation in vitro, including in an allogenic mixed leukocyte reaction (MLR). Three other internal deletion mutants of Nef, spanning amino acids 8-17 (Nef(Delta8-17)), 25-35 (Nef(Delta25-35)), and 57-66 (Nef(Delta57-66)), were also studied. Nef(Delta8-17) retained full pathogenic potential, although Nef(Delta25-35) and Nef(Delta57-66) Tg mice were free of organ disease. However, Nef(Delta25-35) Tg mice exhibited disorganization of thymic architecture and a partial depletion of peripheral CD4+ T cells. These data indicate that myristoylation and other regions at the N-terminus of Nef (aa 25-35 and 57-66) are involved in mediating severe T-cell phenotypes and organ disease, although residues 8-17 are dispensable for these Nef functions. In addition, these results indicate that at least some of the CD4+ T-cell phenotypes can develop independently of the other AIDS-like organ phenotypes. This apparent segregation of different Nef-mediated phenotypes suggests distinct mechanisms of Nef action in different populations of target cells, and may be relevant to human AIDS.
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Affiliation(s)
- Zaher Hanna
- Laboratory of Molecular Biology, Clinical Research Institute of Montreal, Montreal, PQ, Canada H2W 1R7.
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36
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Fortin JF, Barat C, Beauséjour Y, Barbeau B, Tremblay MJ. Hyper-responsiveness to stimulation of human immunodeficiency virus-infected CD4+ T cells requires Nef and Tat virus gene products and results from higher NFAT, NF-kappaB, and AP-1 induction. J Biol Chem 2004; 279:39520-31. [PMID: 15258149 DOI: 10.1074/jbc.m407477200] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A chronic state of immune hyperactivation is a feature of human immunodeficiency virus type-1 (HIV-1) infection. Studies on the molecular mechanisms by which HIV-1 can modulate the activation state of T cells indicate that both Nef and Tat can alter T cell activation. However, the vast majority of data has been obtained from experiments performed with vectors encoding a single virus protein. We demonstrate that infection of human CD4(+) T lymphocytes with fully infectious HIV-1 leads to a hyper-responsiveness of the interleukin-2 promoter. Hypersensitivity in HIV-1-infected T cells was observed upon stimulation with various agents that are engaging different signal transduction pathways. Experiments performed with recombinant heat stable antigen-encoding HIV-1 indicated that the virus-infected cells are the cells with an enhanced response. Both Nef and Tat are involved in this virus-mediated enhancing effect on interleukin-2 promoter activity. Interestingly, whereas Nef seems to be acting mainly through hyperactivation of nuclear factor of activated T cells (NFAT), Tat acts in an NFAT-independent manner. Mobility shift experiments demonstrated that the HIV-1-associated priming of human T cells for stimulation results in a greater induction of transcription factors recognized as essential players in T cell activation, i.e. NFAT, NF-kappaB, and AP-1. A hyper-responsive state was also established upon HIV-1 infection of a more natural cellular reservoir, i.e. primary CD4(+) T lymphocytes. Considering that the HIV-1 life cycle is tightly regulated by the T cell signaling machinery, the priming for activation of a major viral reservoir represents a means by which this retrovirus can create an ideal cellular microenvironment for its propagation and maintenance.
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Affiliation(s)
- Jean-François Fortin
- Baxter Laboratory for Genetic Pharmacology, Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California 94305-5175, USA
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37
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Brown A, Moghaddam S, Kawano T, Cheng-Mayer C. Multiple human immunodeficiency virus type 1 Nef functions contribute to efficient replication in primary human macrophages. J Gen Virol 2004; 85:1463-1469. [PMID: 15166429 DOI: 10.1099/vir.0.79946-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) Nef protein has been shown to accelerate viral growth kinetics in primary human T-lymphocytes and macrophages; however, the specific function(s) of Nef responsible for this phenotype in macrophages is unknown. To address this issue, mutants of a molecularly cloned macrophage-tropic isolate, HIV-1(SF162), were generated expressing single point mutations that abrogate the ability of Nef to interact with cellular kinases or mediate CD4 down-regulation. Infection of primary monocyte-derived macrophages (MDM) with these mutant viruses revealed that residues in the PXXP motif contribute to efficient replication. Interestingly, viruses expressing alleles of Nef defective in CD4 down-modulation activity retain wild-type levels of infectivity in single-round assays but exhibited delayed replication kinetics and grew to lower titres compared to the wild-type virus in MDM. These data suggest that efficient HIV-1 replication is dependent on the ability of Nef to interact with cellular kinases and remove CD4 from the surface of infected macrophages.
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Affiliation(s)
- Amanda Brown
- Aaron Diamond AIDS Research Center, The Rockefeller University, 455 First Avenue, 7th Floor, New York, NY 10016, USA
| | - Shaghayegh Moghaddam
- Aaron Diamond AIDS Research Center, The Rockefeller University, 455 First Avenue, 7th Floor, New York, NY 10016, USA
| | - Thomas Kawano
- Aaron Diamond AIDS Research Center, The Rockefeller University, 455 First Avenue, 7th Floor, New York, NY 10016, USA
| | - Cecilia Cheng-Mayer
- Aaron Diamond AIDS Research Center, The Rockefeller University, 455 First Avenue, 7th Floor, New York, NY 10016, USA
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38
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Weng X, Priceputu E, Chrobak P, Poudrier J, Kay DG, Hanna Z, Mak TW, Jolicoeur P. CD4+ T cells from CD4C/HIVNef transgenic mice show enhanced activation in vivo with impaired proliferation in vitro but are dispensable for the development of a severe AIDS-like organ disease. J Virol 2004; 78:5244-57. [PMID: 15113906 PMCID: PMC400335 DOI: 10.1128/jvi.78.10.5244-5257.2004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The cellular and molecular mechanisms of dysfunction and depletion of CD4+ T lymphocytes over the course of human immunodeficiency virus type 1 (HIV-1) infection are still incompletely understood, but chronic immune activation is thought to play an important role in disease progression. We studied CD4+ T-cell biology in CD4C/HIV transgenic (Tg) mice, in which Nef expression is sufficient to induce a severe AIDS-like disease including a preferential decrease of CD4+ T cells. We show here that Nef-expressing Tg CD4+ T cells exhibit an activated/memory-like phenotype which appears to be independent of antigenic stimulation, as documented in experiments involving breeding with AD10 TcR Tg mice. In addition, in vivo bromodeoxyuridine incorporation showed that a larger proportion of Tg than non-Tg CD4+ T cells entered the S phase. However, in vitro, Tg CD4+ T cells were found to have a very limited capacity to divide in response to stimulation with anti-CD3 and anti-CD28 or in allogeneic mixed leukocyte reactions. Interestingly, despite these observations, the deletion of Tg CD4+ T cells had little impact on the development of other AIDS-like organ phenotypes. Thus, the Nef-induced chronic activation of CD4+ T cells may exhaust the T-cell pool and may contribute to the thymic atrophy and the low number of CD4+ T cells observed in these Tg mice.
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Affiliation(s)
- Xiaoduan Weng
- Laboratory of Molecular Biology, Clinical Research Institute of Montreal, 110 Pine Avenue West, Montreal, Quebec H2W 1R7, Canada
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39
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Yousefi S, Ma XZ, Singla R, Zhou YC, Sakac D, Bali M, Liu Y, Sahai BM, Branch DR. HIV-1 infection is facilitated in T cells by decreasing p56lck protein tyrosine kinase activity. Clin Exp Immunol 2003; 133:78-90. [PMID: 12823281 PMCID: PMC1808751 DOI: 10.1046/j.1365-2249.2003.02187.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Several studies have suggested an important role for the protein tyrosine kinase p56lck (Lck) in HIV infection; however, the exact nature of this role remains unclear. Using a series of well characterized Jurkat-derived cell lines having a wide range of Lck kinase activity, our results showed that, while the entry of HIV-1 into these cell lines was similar, the kinetics of virus production by these cells were very different. Cells expressing a kinase-inactive Lck showed accelerated viral replication, whereas, cells expressing Lck with normal or elevated enzymatic activity showed a delay in virus replication that was proportional to the initial level of endogenous Lck activity. The cell line having the highest initial Lck kinase activity showed the slowest rate of productive HIV-1 infection. Analysis of 2-LTR circles revealed that this inhibitory effect of Lck was not due to inhibition of reverse transcription of HIV-1 genome or migration of the proviral DNA into the nuclei. This affect of Lck was confirmed in additional studies that used either the S1T cell line lacking completely Lck or where the Lck activity was altered in Jurkat cells prior to infection. S1T cells showed a 3- to 12-fold increase in the level of infection compared to Jurkat cells despite similar CD4 and chemokine coreceptor expression and cell doubling times. Pretreatment of Jurkat with an antisense lck oligodeoxynucleotide inhibited the synthesis of functional Lck and facilitated the viral replication by the cells as did expressing a dominant-negative mutant Lck which increased the productive infection>3-fold. Conversely, whereas IL-16 had no affect on productive infection in S1T cells that lack Lck, IL-16 pretreatment of Jurkat cells resulted in an immediate (within 5 min) and sustained and gradual (over 5 h) increase in Lck activity that resulted in a reduction of HIV-1 replication that paralleled the increasing Lck kinase activity. These results show that the enzymatic activity of Lck kinase can affect viral replication, that a lack of, or decreased Lck activity facilitates viral replication. Conversely, Lck can mediate a delay in HIV-1 infection that is proportional to the initial endogenous Lck enzyme activity.
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Affiliation(s)
- S Yousefi
- Department of Medicine, University of Toronto, Toronto, Ontario, Canada
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40
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Alexander L, Illyinskii PO, Lang SM, Means RE, Lifson J, Mansfield K, Desrosiers RC. Determinants of increased replicative capacity of serially passaged simian immunodeficiency virus with nef deleted in rhesus monkeys. J Virol 2003; 77:6823-35. [PMID: 12768002 PMCID: PMC156171 DOI: 10.1128/jvi.77.12.6823-6835.2003] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Most rhesus macaques infected with simian immunodeficiency virus SIVmac239 with nef deleted (either Delta nef or Delta nef Delta vpr Delta US [Delta 3]) control viral replication and do not progress to AIDS. Some monkeys, however, develop moderate viral load set points and progress to AIDS. When simian immunodeficiency viruses (SIVs) recovered from two such animals (one Delta nef and the other Delta 3) were serially passaged in rhesus monkeys, the SIVs derived from both lineages were found to consistently induce moderate viral loads and disease progression. Analysis of viral sequences in the serially passaged derivatives revealed interesting changes in three regions: (i) an unusually high number of predicted amino acid changes (12 to 14) in the cytoplasmic domain of gp41, most of which were in regions that are usually conserved; these changes were observed in both lineages; (ii) an extreme shortening of nef sequences in the region of overlap with U3; these changes were observed in both lineages; and (iii) duplication of the NF-kappa B binding site in one lineage only. Neither the polymorphic gp41 changes alone nor the U3 deletion alone appeared to be responsible for increased replicative capacity because recombinant SIVmac239 Delta nef, engineered to contain either of these changes, induced moderate viral loads in only one of six monkeys. However, five of six monkeys infected with recombinant SIVmac239 Delta nef containing both TM and U3 changes did develop persisting moderate viral loads. These genetic changes did not increase lymphoid cell-activating properties in the monkey interleukin-2-dependent T-cell line 221, but the gp41 changes did increase the fusogenic activity of the SIV envelope two- to threefold. These results delineate sequence changes in SIV that can compensate for the loss of the nef gene to partially restore replicative and pathogenic potential in rhesus monkeys.
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Affiliation(s)
- Louis Alexander
- Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, Connecticut, USA
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41
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Padua E, Jenkins A, Brown S, Bootman J, Paixao MT, Almond N, Berry N. Natural variation of the nef gene in human immunodeficiency virus type 2 infections in Portugal. J Gen Virol 2003; 84:1287-1299. [PMID: 12692296 DOI: 10.1099/vir.0.18908-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Human immunodeficiency virus type 2 (HIV-2) infections cause severe immunodeficiency in humans, although HIV-2 is associated frequently with reduced virulence and pathogenicity compared to HIV-1. Genetic determinants that play a role in HIV pathogenesis are relatively poorly understood but nef has been implicated in inducing a more pathogenic phenotype in vivo. However, relatively little is known about the role of nef in HIV-2 pathogenesis. To address this, the genetic composition of 44 nef alleles from 37 HIV-2-infected individuals in Portugal, encompassing a wide spectrum of disease associations, CD4 counts and virus load, has been assessed. All nef alleles were subtype A, with no evidence of gross deletions, truncations or disruptions in the nef-encoding sequence; all were full-length and intact. HIV-2 long terminal repeat sequences were conserved and also indicated subtype A infections. Detailed analysis of motifs that mediate nef function in HIV-1 and simian immunodeficiency virus, such as CD4 downregulation and putative SH2/SH3 interactions, revealed significant natural variation. In particular, the central P(104)xxPLR motif exhibited wide interpatient variation, ranging from an HIV-1-like tetra-proline structure (PxxP)(3) to a disrupted minimal core motif (P(104)xxQLR). The P(107)-->Q substitution was associated with an asymptomatic phenotype (Fisher's exact test, P=0.026) and low virus loads. These data indicate that discrete differences in the nef gene sequence rather than gross structural changes are more likely to play a role in HIV-2 pathogenesis mediated via specific functional interactions.
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Affiliation(s)
- Elizabeth Padua
- AIDS Reference Laboratory, National Institute of Health, Av. Padre Cruz, 1649-016 Lisbon, Portugal
| | - Adrian Jenkins
- Division of Retrovirology, National Institute for Biological Standards and Control, Blanche Lane, South Mimms, Potters Bar, Hertfordshire EN6 3QG, UK
| | - Stuart Brown
- Division of Retrovirology, National Institute for Biological Standards and Control, Blanche Lane, South Mimms, Potters Bar, Hertfordshire EN6 3QG, UK
| | - Janet Bootman
- Division of Retrovirology, National Institute for Biological Standards and Control, Blanche Lane, South Mimms, Potters Bar, Hertfordshire EN6 3QG, UK
| | - Maria Teresa Paixao
- AIDS Reference Laboratory, National Institute of Health, Av. Padre Cruz, 1649-016 Lisbon, Portugal
| | - Neil Almond
- Division of Retrovirology, National Institute for Biological Standards and Control, Blanche Lane, South Mimms, Potters Bar, Hertfordshire EN6 3QG, UK
| | - Neil Berry
- Division of Retrovirology, National Institute for Biological Standards and Control, Blanche Lane, South Mimms, Potters Bar, Hertfordshire EN6 3QG, UK
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Capo C, Moynault A, Collette Y, Olive D, Brown EJ, Raoult D, Mege JL. Coxiella burnetii avoids macrophage phagocytosis by interfering with spatial distribution of complement receptor 3. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:4217-25. [PMID: 12682255 DOI: 10.4049/jimmunol.170.8.4217] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Phagocytosis is a highly localized event requiring the formation of spatially and temporally restricted signals. Numerous microorganisms have taken advantage of this property to invade host cells. Coxiella burnetii, the agent of Q fever, is an obligate intracellular bacterium that has developed a survival strategy in macrophages based on subversion of receptor-mediated phagocytosis. The uptake of C. burnetii is mediated by alpha(v)beta(3) integrin and is restricted by impaired cross-talk of alpha(v)beta(3) integrin and complement receptor 3 (CR3) (CD11b/CD18). In this study, we showed that CR3 molecules remained outside the pseudopodal extensions induced by C. burnetii in THP-1 monocytes, although alpha(v)beta(3) integrin was present in the pseudopods. Chemoattractants such as RANTES restored CR3 localization to the front of pseudopodal extensions and increased C. burnetii phagocytosis, demonstrating that the localization of CR3 is critical for bacterial uptake. In addition, monocyte activation due to the expression of HIV-1 Nef protein also restored CR3-mediated phagocytosis of C. burnetii by allowing CR3 redistribution toward bacterial-induced pseudopods. The redistribution of CR3 and increased C. burnetii phagocytosis in THP-1 cells stimulated by RANTES or expressing Nef were associated with the inhibition of intracellular replication of C. burnetii. Hence, the localization of CR3 is critical for bacterial phagocytosis and also for the control of bacterial replication. This study describes a nonpreviously reported strategy of phagocytosis subversion by intracellular pathogens based on altered localization of monocyte receptors.
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Affiliation(s)
- Christian Capo
- Unité des Rickettsies, Faculté de Médecine, Centre National de la Recherche Scientifique Unité Mixte de Recherche 6020, Marseille, France
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Greenway AL, Holloway G, McPhee DA, Ellis P, Cornall A, Lidman M. HIV-1 Nef control of cell signalling molecules: multiple strategies to promote virus replication. J Biosci 2003; 28:323-35. [PMID: 12734410 DOI: 10.1007/bf02970151] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
HIV-1 has at its disposal numerous proteins encoded by its genome which provide the required arsenal to establish and maintain infection in its host for a considerable number of years. One of the most important and enigmatic of these proteins is Nef. The Nef protein of HIV-1 plays a fundamental role in the virus life cycle. This small protein of approximately 27 kDa is required for maximal virus replication and disease progression. The mechanisms by which it is able to act as a positive factor during virus replication is an area of intense research and although some controversy surrounds Nef much has been gauged as to how it functions. Its ability to modulate the expression of key cellular receptors important for cell activation and control signal transduction elements and events by interacting with numerous cellular kinases and signalling molecules, including members of the Src family kinases, leading to an effect on host cell function is likely to explain at least in part its role during infection and represents a finely tuned mechanism where this protein assists HIV-1 to control its host.
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Affiliation(s)
- Alison L Greenway
- Macfarlane Burnet Institute for Medical Research and Public Health, Cnr Commercial and Punt Roads, Melbourne, Victoria 3004, Australia.
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44
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Varin A, Manna SK, Quivy V, Decrion AZ, Van Lint C, Herbein G, Aggarwal BB. Exogenous Nef protein activates NF-kappa B, AP-1, and c-Jun N-terminal kinase and stimulates HIV transcription in promonocytic cells. Role in AIDS pathogenesis. J Biol Chem 2003; 278:2219-27. [PMID: 12419805 DOI: 10.1074/jbc.m209622200] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The human immunodeficiency virus (HIV) Nef protein plays a critical role in AIDS pathogenesis by enhancing replication and survival of the virus within infected cells and by facilitating its spread in vivo. Most of the data obtained so far have been in experiments with endogenous Nef protein, so far overlooking the effects of exogenous soluble Nef protein. We used recombinant exogenous Nef proteins to activate nuclear transcription factors NF-kappaB and AP-1 in the promonocytic cell line U937. Exogenous SIV and HIV-1 Nef proteins activated NF-kappaB and AP-1 in a dose- and time-dependent manner. Activation of NF-kappaB by exogenous Nef was concomitant to the degradation of the inhibitor of NF-kappaB, IkappaBalpha. In agreement with increased AP-1 activation, a time- and dose-dependent increase in JNK activation was observed following treatment of U937 cells with exogenous Nef. Since exogenous Nef activates the transcription factors NF-kappaB and AP-1, which bind to the HIV-1 long terminal repeat (LTR), we investigated the effect of exogenous Nef on HIV-1 replication. We observed that exogenous Nef stimulated HIV-1 LTR via NF-kappaB activation in U937 cells and enhanced viral replication in the chronically infected promonocytic cells U1. Therefore, our results suggest that exogenous Nef could fuel the progression of the disease via stimulation of HIV-1 provirus present in such cellular reservoirs as mononuclear phagocytes in HIV-infected patients.
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Affiliation(s)
- Audrey Varin
- Department of Virology and Institut d'Etude et de Transfert de Gènes, Franche-Comté University, F-25030 Besançon, France
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46
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Oh HS, Kwon H, Sun SK, Yang CH. QM, a putative tumor suppressor, regulates proto-oncogene c-yes. J Biol Chem 2002; 277:36489-98. [PMID: 12138090 DOI: 10.1074/jbc.m201859200] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The QM gene encodes a 24.5 kDa ribosomal protein L10 known to be highly homologous to a Jun-binding protein (Jif-1), which inhibits the formation of Jun-Jun dimers. Here we have carried out screening with the c-Yes protein and found that a QM homologous protein showed interactions with c-Yes and other Src family members. We have found that two different regions of QM protein were associated with the SH3 domain of c-Yes. The QM protein does not contain canonical SH3 binding motifs or previously reported amino acid fragments showing interaction with SH3 domains. Several c-Yes kinase activity assays indicated that the QM protein reduced c-Yes kinase activity by 70% and that this suppression is related not only to the two SH3 binding regions but also to the C-terminal region of QM. Moreover, our autophosphorylation assays clarified that this regulation resulted from the inhibition of c-Yes autophosphorylation. Immunofluorescence studies showed that the QM proteins and c-Yes are able to interact in various tumor cell lines in vivo. The increases of the c-Yes protein and mRNA levels were detected when the QM was transfected. These results suggest that the QM protein might be a regulator for various signal transduction pathways involving SH3 domain-containing membrane proteins.
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Affiliation(s)
- Hyung Suk Oh
- Division of Chemistry and Molecular Engineering, Seoul National University, Seoul 151-742, Korea
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47
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Hel Z, Tryniszewska E, Tsai WP, Johnson JM, Harrod R, Fullen J, Kalyanaraman VS, Altman JD, McNally J, Karpova T, Felber BK, Tartaglia J, Franchini G. Design and in vivo immunogenicity of a polyvalent vaccine based on SIVmac regulatory genes. DNA Cell Biol 2002; 21:619-26. [PMID: 12396604 DOI: 10.1089/104454902760330156] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Most vaccine modalities for human immunodeficiency virus type 1 (HIV-1) tested for immunogenicity and efficacy in the SIVmac (simian immunodeficiency virus) macaque model do not include the viral regulatory proteins. Because viral regulatory proteins are expressed early during the virus life cycle and represent an additional source of antigens, their inclusion as a vaccine component may increase the overall virus-specific immune response in vaccinees. However, at least two of the early proteins, Tat and Nef, may be immunosuppressive, limiting their usefulness as components of an SIV vaccine. We have constructed a polyvalent chimeric protein in which the open reading frames for Tat and Nef have been reassorted and the nuclear localization sequence for Tat and Rev and the myristoylation site for Nef have been removed. The resulting DNA plasmid (pDNA-SIV-Retanef) (pDNA-SIV-RTN) encodes a protein of 55 kDa (Retanef) that localizes at the steady state in the cytoplasma of transfected cells. Both the DNA-SIV-RTN and the highly attenuated recombinant poxvirus vector NYVAC-SIV-RTN were demonstrated to be immunogenic in SIVmac251-infected macaques treated with ART as well as in naive macaques. An equivalent strategy may be used for the generation of polyvalent antigens encoding the regulatory proteins in a HIV-1 vaccine candidate.
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Affiliation(s)
- Z Hel
- National Cancer Institute, Basic Research Laboratory, 41/D804, Bethesda, Maryland 20892, USA
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Manninen A, Saksela K. HIV-1 Nef interacts with inositol trisphosphate receptor to activate calcium signaling in T cells. J Exp Med 2002; 195:1023-32. [PMID: 11956293 PMCID: PMC2193699 DOI: 10.1084/jem.20012039] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
HIV-1 pathogenicity factor Nef has been shown to modulate calcium signaling in host cells, but the underlying molecular mechanisms have remained unclear. Here we show that calcium/calcineurin-dependent activation of nuclear factor of activated T cells (NFAT) by Nef in Jurkat T cells requires the endoplasmic reticulum-resident inositol trisphosphate receptor (IP(3)R), but yet does not involve increase in phospholipase-C gamma 1 (PLC gamma 1)-catalyzed production of IP(3) or depletion of IP(3)-regulated intracellular calcium stores. Nef could be coprecipitated with endogenous IP(3)R type-1 (IP(3)R1) from Nef-transfected Jurkat T cells as well as from HIV-infected primary human peripheral mononuclear cells. Thus, the Nef/IP(3)R1-interaction defines a novel T cell receptor-independent mechanism by which Nef can promote T cell activation, and appears to involve atypical IP(3)R-triggered activation of plasma membrane calcium influx channels in a manner that is uncoupled from depletion of intracellular calcium stores.
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Affiliation(s)
- Aki Manninen
- Institute of Medical Technology, University of Tampere, Tampere FIN-33014, Finland
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Picard C, Greenway A, Holloway G, Olive D, Collette Y. Interaction with simian Hck tyrosine kinase reveals convergent evolution of the Nef protein from simian and human immunodeficiency viruses despite differential molecular surface usage. Virology 2002; 295:320-7. [PMID: 12033791 DOI: 10.1006/viro.2002.1381] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Simian and human immunodeficiency virus type 1 (SIV and HIV-1) Nef proteins are thought to use different molecular surfaces to mediate the protein-protein interactions required for their otherwise similar functions. This genetically separable function suggests convergent evolution of primate lentiviruses and/or structural differences between human and nonhuman primate cellular target proteins. However, such comparative molecular analyses have not been undertaken so far using the respective natural host-derived cellular targets. We cloned simian Src family kinase Hck and analyzed structurally and biochemically its interaction with SIV Nef.
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Affiliation(s)
- C Picard
- Institut de Cancérologie et d'Immunologie de Marseille, U119 INSERM, 27 boulevard Leï Roure, 13009, France
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50
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Greenway AL, McPhee DA, Allen K, Johnstone R, Holloway G, Mills J, Azad A, Sankovich S, Lambert P. Human immunodeficiency virus type 1 Nef binds to tumor suppressor p53 and protects cells against p53-mediated apoptosis. J Virol 2002; 76:2692-702. [PMID: 11861836 PMCID: PMC135999 DOI: 10.1128/jvi.76.6.2692-2702.2002] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The nef gene product of human immunodeficiency virus type 1 (HIV-1) is important for the induction of AIDS, and key to its function is its ability to manipulate T-cell function by targeting cellular signal transduction proteins. We reported that Nef coprecipitates a multiprotein complex from cells which contains tumor suppressor protein p53. We now show that Nef interacts directly with p53. Binding assays showed that an N-terminal, 57-residue fragment of Nef (Nef 1-57) contains the p53-binding domain. Nef also interacted with p53 during HIV-1 infection in vitro. As p53 plays a critical role in the regulation of apoptosis, we hypothesized that Nef may alter this process. Nef inhibited UV light-induced, p53-dependent apoptosis in MOLT-4 cells, with Nef 1-57 being as effective as its full-length counterpart. The inhibition by Nef of p53 apoptotic function is most likely due its observed ability to decrease p53 protein half-life and, consequently, p53 DNA binding activity and transcriptional activation. These data show that HIV-1 Nef may augment HIV replication by prolonging the viability of infected cells by blocking p53-mediated apoptosis.
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Affiliation(s)
- Alison L Greenway
- AIDS Cellular Biology Unit, Macfarlane Burnet Centre for Medical Research, Fairfield, Victoria 3078, Australia.
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