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Biradar S, Agarwal Y, Das A, Shu ST, Samal J, Ho S, Kelly N, Mahesh D, Teredesai S, Castronova I, Mussina L, Mailliard RB, Smithgall TE, Bility MT. Nef defect attenuates HIV viremia and immune dysregulation in the bone marrow-liver-thymus-spleen (BLTS) humanized mouse model. Virology 2024; 598:110192. [PMID: 39106585 DOI: 10.1016/j.virol.2024.110192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Revised: 07/21/2024] [Accepted: 07/24/2024] [Indexed: 08/09/2024]
Abstract
In vitro studies have shown that deletion of nef and deleterious mutation in the Nef dimerization interface attenuates HIV replication and associated pathogenesis. Humanized rodents with human immune cells and lymphoid tissues are robust in vivo models for investigating the interactions between HIV and the human immune system. Here, we demonstrate that nef deletion impairs HIV replication and HIV-induced immune dysregulation in the blood and human secondary lymphoid tissue (human spleen) in bone marrow-liver-thymus-spleen (BLTS) humanized mice. Furthermore, we also show that nef defects (via deleterious mutations in the dimerization interface) impair HIV replication and HIV-induced immune dysregulation in the blood and human spleen in BLTS-humanized mice. We demonstrate that the reduced replication of nef-deleted and nef-defective HIV is associated with robust antiviral innate immune response, and T helper 1 response. Our results support the proposition that Nef may be a therapeutic target for adjuvants in HIV cure strategies.
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Affiliation(s)
- Shivkumar Biradar
- Department of Infectious Diseases and Microbiology, University of Pittsburgh, School of Public Health, Pittsburgh, PA, USA
| | - Yash Agarwal
- Department of Infectious Diseases and Microbiology, University of Pittsburgh, School of Public Health, Pittsburgh, PA, USA
| | - Antu Das
- Department of Infectious Diseases and Microbiology, University of Pittsburgh, School of Public Health, Pittsburgh, PA, USA
| | - Sherry T Shu
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Jasmine Samal
- Department of Infectious Diseases and Microbiology, University of Pittsburgh, School of Public Health, Pittsburgh, PA, USA
| | - Sara Ho
- Department of Infectious Diseases and Microbiology, University of Pittsburgh, School of Public Health, Pittsburgh, PA, USA
| | - Nickolas Kelly
- Department of Infectious Diseases and Microbiology, University of Pittsburgh, School of Public Health, Pittsburgh, PA, USA
| | - Deepika Mahesh
- Department of Infectious Diseases and Microbiology, University of Pittsburgh, School of Public Health, Pittsburgh, PA, USA
| | - Shreya Teredesai
- Department of Infectious Diseases and Microbiology, University of Pittsburgh, School of Public Health, Pittsburgh, PA, USA
| | - Isabella Castronova
- Department of Infectious Diseases and Microbiology, University of Pittsburgh, School of Public Health, Pittsburgh, PA, USA
| | - London Mussina
- Department of Infectious Diseases and Microbiology, University of Pittsburgh, School of Public Health, Pittsburgh, PA, USA
| | - Robbie B Mailliard
- Department of Infectious Diseases and Microbiology, University of Pittsburgh, School of Public Health, Pittsburgh, PA, USA
| | - Thomas E Smithgall
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Moses T Bility
- Department of Infectious Diseases and Microbiology, University of Pittsburgh, School of Public Health, Pittsburgh, PA, USA; Department of Microbiology, Howard University, Washington, DC, USA.
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2
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Aryal M, Lin D, Regan K, Du S, Shi H, Alvarado JJ, Ilina TV, Andreotti AH, Smithgall TE. The HIV-1 protein Nef activates the Tec family kinase Btk by stabilizing an intermolecular SH3-SH2 domain interaction. Sci Signal 2022; 15:eabn8359. [PMID: 36126115 PMCID: PMC9830684 DOI: 10.1126/scisignal.abn8359] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The Nef protein produced by the viruses HIV-1 and SIV drives efficient viral replication partially by inducing constitutive activation of host cell tyrosine kinases, including members of the Src and Tec families. Here, we uncovered the mechanism by which both HIV-1 and SIV Nef enhanced the activity of the Tec family kinase Btk in vitro and in cells. A Nef mutant that could not bind to the SH3 domain of Src family kinases activated Btk to the same extent as did wild-type Nef, demonstrating that Nef activated Src and Tec family kinases by distinct mechanisms. The Btk SH3-SH2 region formed a homodimer requiring the CD loop in the SH2 domain, which was stabilized by the binding of Nef homodimers. Alanine substitution of Pro327 in the CD loop of the Btk SH2 domain destabilized SH3-SH2 dimers, abolished the interaction with Nef, and prevented activation by Nef in vitro. In cells, Nef stabilized and activated wild-type but not P327A Btk homodimers at the plasma membrane. These data reveal that the interaction with Nef stabilizes Btk dimers through the SH3-SH2 interface to promote kinase activity and show that the HIV-1 Nef protein evolved distinct mechanisms to activate Src and Tec family tyrosine kinases to enhance viral replication.
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Affiliation(s)
- Manish Aryal
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh PA, 15219 USA
| | - David Lin
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA, 50011 USA
| | - Kiera Regan
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh PA, 15219 USA
| | - Shoucheng Du
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh PA, 15219 USA
| | - Haibin Shi
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh PA, 15219 USA
| | - John J. Alvarado
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh PA, 15219 USA
| | - Tatiana V. Ilina
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh PA, 15260 USA
| | - Amy H. Andreotti
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA, 50011 USA
| | - Thomas E. Smithgall
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh PA, 15219 USA,To whom correspondence should be addressed: Thomas E. Smithgall, Ph.D., Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Bridgeside Point II, Suite 523, 450 Technology Drive, Pittsburgh, PA 15219, Tel. 412-648-8106, Fax 412-624-8997,
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3
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Emert-Sedlak LA, Moukha-Chafiq O, Shi H, Du S, Alvarado JJ, Pathak V, Tanner SG, Hunter RN, Nebane M, Chen L, Ilina TV, Ishima R, Zhang S, Kuzmichev YV, Wonderlich ER, Schader SM, Augelli-Szafran CE, Ptak RG, Smithgall TE. Inhibitors of HIV-1 Nef-Mediated Activation of the Myeloid Src-Family Kinase Hck Block HIV-1 Replication in Macrophages and Disrupt MHC-I Downregulation. ACS Infect Dis 2022; 8:91-105. [PMID: 34985256 PMCID: PMC9274903 DOI: 10.1021/acsinfecdis.1c00288] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
HIV-1 Nef is an attractive target for antiretroviral drug discovery because of its role in promoting HIV-1 infectivity, replication, and host immune system avoidance. Here, we applied a screening strategy in which recombinant HIV-1 Nef protein was coupled to activation of the Src-family tyrosine kinase Hck, which enhances the HIV-1 life cycle in macrophages. Nef stimulates recombinant Hck activity in vitro, providing a robust assay for chemical library screening. High-throughput screening of more than 730 000 compounds using the Nef·Hck assay identified six unique hit compounds that bound directly to recombinant Nef by surface plasmon resonance (SPR) in vitro and inhibited HIV-1 replication in primary macrophages in the 0.04 to 5 μM range without cytotoxicity. Eighty-four analogs were synthesized around an isothiazolone scaffold from this series, many of which bound to recombinant Nef and inhibited HIV-1 infectivity in the low to submicromolar range. Compounds in this series restored MHC-I to the surface of HIV-infected primary cells and disrupted a recombinant protein complex of Nef with the C-terminal tail of MHC-I and the μ1 subunit of the AP-1 endocytic trafficking protein. Nef inhibitors in this class have the potential to block HIV-1 replication in myeloid cells and trigger recognition of HIV-infected cells by the adaptive immune system in vivo.
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Affiliation(s)
- Lori A. Emert-Sedlak
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, PA 15219
| | - Omar Moukha-Chafiq
- Department of Chemistry, Southern Research Institute, 2000 Ninth Avenue South, Birmingham, AL 35205
| | - Haibin Shi
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, PA 15219
| | - Shoucheng Du
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, PA 15219
| | - John J. Alvarado
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, PA 15219
| | - Vibha Pathak
- Department of Chemistry, Southern Research Institute, 2000 Ninth Avenue South, Birmingham, AL 35205
| | - Samuel G. Tanner
- Department of Chemistry, Southern Research Institute, 2000 Ninth Avenue South, Birmingham, AL 35205
| | - Robert N. Hunter
- Department of Chemistry, Southern Research Institute, 2000 Ninth Avenue South, Birmingham, AL 35205
| | - Miranda Nebane
- Department of High-throughput Screening, Drug Discovery Division, Southern Research Institute, 2000 Ninth Avenue South, Birmingham, AL 35205
| | - Li Chen
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, PA 15219
| | - Tatiana V. Ilina
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Avenue, Pittsburgh, PA 15260
| | - Rieko Ishima
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Avenue, Pittsburgh, PA 15260
| | - Sixue Zhang
- Department of High-throughput Screening, Drug Discovery Division, Southern Research Institute, 2000 Ninth Avenue South, Birmingham, AL 35205
| | - Yury V. Kuzmichev
- Department of Infectious Disease Research, Drug Development Division, Southern Research Institute, 431 Aviation Way, Frederick, MD 21701
| | - Elizabeth R. Wonderlich
- Department of Infectious Disease Research, Drug Development Division, Southern Research Institute, 431 Aviation Way, Frederick, MD 21701
| | - Susan M. Schader
- Department of Infectious Disease Research, Drug Development Division, Southern Research Institute, 431 Aviation Way, Frederick, MD 21701
| | | | - Roger G. Ptak
- Department of Infectious Disease Research, Drug Development Division, Southern Research Institute, 431 Aviation Way, Frederick, MD 21701
| | - Thomas E. Smithgall
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, PA 15219
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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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Abstract
The focus of this review is to examine the role of ITK signaling in multiple diseases and investigate the clinical potential of ITK inhibition. The diseases and potential interventions reviewed include T cell-derived malignancies as well as other neoplastic diseases, allergic diseases such as asthma and atopic dermatitis, certain infectious diseases, several autoimmune disorders such as rheumatoid arthritis and psoriasis, and finally the use of ITK inhibition in both solid organ and bone marrow transplantation recipients.
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Affiliation(s)
- Samuel Weeks
- Department of Microbiology and Immunology, SUNY Upstate Medical University, 766 Irving Avenue Weiskotten Hall Suite 2281, Syracuse, NY 13210, USA
| | - Rebecca Harris
- Department of Microbiology and Immunology, SUNY Upstate Medical University, 766 Irving Avenue Weiskotten Hall Suite 2281, Syracuse, NY 13210, USA
| | - Mobin Karimi
- Department of Microbiology and Immunology, SUNY Upstate Medical University, 766 Irving Avenue Weiskotten Hall Suite 2281, Syracuse, NY 13210, USA
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6
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Shu ST, Li WF, Smithgall TE. Visualization of Host Cell Kinase Activation by Viral Proteins Using GFP Fluorescence Complementation and Immunofluorescence Microscopy. Bio Protoc 2021; 11:e4068. [PMID: 34327265 DOI: 10.21769/bioprotoc.4068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 03/29/2021] [Accepted: 04/01/2021] [Indexed: 11/02/2022] Open
Abstract
Non-receptor protein-tyrosine kinases regulate cellular responses to many external signals and are important drug discovery targets for cancer and infectious diseases. While many assays exist for the assessment of kinase activity in vitro, methods that report changes in tyrosine kinase activity in single cells have the potential to provide information about kinase responses at the cell population level. In this protocol, we combined bimolecular fluorescence complementation (BiFC), an established method for the assessment of protein-protein interactions, and immunofluorescence staining with phosphospecific antibodies to characterize changes in host cell tyrosine kinase activity in the presence of an HIV-1 virulence factor, Nef. Specifically, two Tec family kinases (Itk and Btk) as well as Nef were fused to complementary, non-fluorescent fragments of the Venus variant of YFP. Each kinase was expressed in 293T cells in the presence or absence of Nef and immunostained for protein expression and activity with anti-phosphotyrosine (pTyr) antibodies. Multi-color confocal microscopy revealed the interaction of Nef with each kinase (BiFC), kinase activity, and kinase protein expression. Strong BiFC signals were observed when Nef was co-expressed with both Itk and Btk, indicative of interaction, and a strong anti-pTyr immunoreactivity was also seen. The BiFC, pTyr, and kinase expression signals co-localized to the plasma membrane, consistent with Nef-mediated kinase activation in this subcellular compartment. Image analysis allowed calculation of pTyr-to-kinase protein ratios, which showed a range of responses in individual cells across the population that shifted upward in the presence of Nef and back down in the presence of a kinase inhibitor. This method has the potential to reveal changes in steady-state non-receptor tyrosine kinase activity and subcellular localization in a cell population in response to other protein-kinase interactions, information that is not attainable from immunoblotting or other in vitro methods.
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Affiliation(s)
- Sherry T Shu
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA
| | - Wing Fai Li
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA
| | - Thomas E Smithgall
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA
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7
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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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8
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Staudt RP, Smithgall TE. Nef homodimers down-regulate SERINC5 by AP-2-mediated endocytosis to promote HIV-1 infectivity. J Biol Chem 2020; 295:15540-15552. [PMID: 32873704 DOI: 10.1074/jbc.ra120.014668] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 08/24/2020] [Indexed: 12/13/2022] Open
Abstract
SERINC5 is a multipass intrinsic membrane protein that suppresses HIV-1 infectivity when incorporated into budding virions. The HIV-1 Nef virulence factor prevents viral incorporation of SERINC5 by triggering its down-regulation from the producer cell membrane through an AP-2-dependent endolysosomal pathway. However, the mechanistic basis for SERINC5 down-regulation by Nef remains elusive. Here we demonstrate that Nef homodimers are important for SERINC5 down-regulation, trafficking to late endosomes, and exclusion from newly synthesized viral particles. Based on previous X-ray crystal structures, we mutated three conserved residues in the Nef dimer interface (Leu112, Tyr115, and Phe121) and demonstrated attenuated homodimer formation in a cell-based fluorescence complementation assay. Point mutations at each position reduced the infectivity of HIV-1 produced from transfected 293T cells, the Jurkat TAg T-cell line, and donor mononuclear cells in a SERINC5-dependent manner. In SERINC5-transfected 293T cells, virion incorporation of SERINC5 was increased by dimerization-defective Nef mutants, whereas down-regulation of SERINC5 from the membrane of transfected Jurkat cells by these mutants was significantly reduced. Nef dimer interface mutants also failed to trigger internalization of SERINC5 and localization to Rab7+ late endosomes in T cells. Importantly, fluorescence complementation assays demonstrated that dimerization-defective Nef mutants retained interaction with both SERINC5 and AP-2. These results show that down-regulation of SERINC5 and subsequent enhancement of viral infectivity require Nef homodimers and support a mechanism by which the Nef dimer bridges SERINC5 to AP-2 for endocytosis. Pharmacological disruption of Nef homodimers may control HIV-1 infectivity and viral spread by enhancing virion incorporation of SERINC5.
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Affiliation(s)
- Ryan P Staudt
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Thomas E Smithgall
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, USA.
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9
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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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10
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Li WF, Aryal M, Shu ST, Smithgall TE. HIV-1 Nef dimers short-circuit immune receptor signaling by activating Tec-family kinases at the host cell membrane. J Biol Chem 2020; 295:5163-5174. [PMID: 32144207 DOI: 10.1074/jbc.ra120.012536] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 03/04/2020] [Indexed: 01/08/2023] Open
Abstract
The HIV-1 virulence factor Nef promotes high-titer viral replication, immune escape, and pathogenicity. Nef interacts with interleukin-2-inducible T-cell kinase (Itk) and Bruton's tyrosine kinase (Btk), two Tec-family kinases expressed in HIV-1 target cells (CD4 T cells and macrophages, respectively). Using a cell-based bimolecular fluorescence complementation assay, here we demonstrate that Nef recruits both Itk and Btk to the cell membrane and induces constitutive kinase activation in transfected 293T cells. Nef homodimerization-defective mutants retained their interaction with both kinases but failed to induce activation, supporting a role for Nef homodimer formation in the activation mechanism. HIV-1 infection up-regulates endogenous Itk activity in SupT1 T cells and donor-derived peripheral blood mononuclear cells. However, HIV-1 strains expressing Nef variants with mutations in the dimerization interface replicated poorly and were significantly attenuated in Itk activation. We conclude that direct activation of Itk and Btk by Nef at the membrane in HIV-infected cells may override normal immune receptor control of Tec-family kinase activity to enhance the viral life cycle.
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Affiliation(s)
- Wing Fai Li
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, Pennsylvania 15219
| | - Manish Aryal
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, Pennsylvania 15219
| | - Sherry T Shu
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, Pennsylvania 15219
| | - Thomas E Smithgall
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, Pennsylvania 15219
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11
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Shi H, Tice CM, Emert-Sedlak L, Chen L, Li WF, Carlsen M, Wrobel JE, Reitz AB, Smithgall TE. Tight-Binding Hydroxypyrazole HIV-1 Nef Inhibitors Suppress Viral Replication in Donor Mononuclear Cells and Reverse Nef-Mediated MHC-I Downregulation. ACS Infect Dis 2020; 6:302-312. [PMID: 31775511 DOI: 10.1021/acsinfecdis.9b00382] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The HIV-1 Nef accessory factor is critical to the viral life cycle in vivo and promotes immune escape of infected cells via downregulation of cell-surface MHC-I. Previously, we discovered small molecules that bind directly to Nef and block many of its functions, including enhancement of viral infectivity and replication in T cell lines. These compounds also restore cell-surface MHC-I expression in HIV-infected CD4 T cells from AIDS patients, enabling recognition and killing by autologous cytotoxic T lymphocytes (CTLs). In this study, we describe the synthesis and evaluation of a diverse set of analogs based on the original hydroxypyrazole Nef inhibitor core. All analogs were screened for the interaction with recombinant HIV-1 Nef by surface plasmon resonance (SPR) and for antiretroviral activity in TZM-bl reporter cells infected with HIV-1. Active analogs were ranked on the basis of an activity score that integrates three aspects of the SPR data (affinity, residence time, and extent of binding) with antiretroviral activity. The top scoring compounds bound tightly to Nef by SPR, with KD values in the low nM to pM range, and displayed very slow dissociation from their Nef target. These analogs also suppressed HIV-1 replication in donor peripheral blood mononuclear cells (PBMCs) with IC50 values in the 1-10 nM range without cytotoxicity, inhibited Nef-mediated IL-2-inducible tyrosine kinase (Itk) and hematopoietic cell kinase (Hck) activation, and rescued MHC-I downregulation in a Nef-transfected T cell line. The development of Nef inhibitors based on the structure-activity relationships defined here has promise as a new approach to antiretroviral therapy that includes a path to eradication of HIV-infected cells via the adaptive immune response.
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Affiliation(s)
- Haibin Shi
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Suite 523 Bridgeside Point II, 450 Technology Drive, Pittsburgh, Pennsylvania 15219, United States
| | - Colin M. Tice
- Fox Chase Chemical Diversity Center, Inc., Pennsylvania Biotechnology Center, 3805 Old Easton Road, Doylestown, Pennsylvania 18902, United States
| | - Lori Emert-Sedlak
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Suite 523 Bridgeside Point II, 450 Technology Drive, Pittsburgh, Pennsylvania 15219, United States
| | - Li Chen
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Suite 523 Bridgeside Point II, 450 Technology Drive, Pittsburgh, Pennsylvania 15219, United States
| | - Wing Fai Li
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Suite 523 Bridgeside Point II, 450 Technology Drive, Pittsburgh, Pennsylvania 15219, United States
| | - Marianne Carlsen
- Fox Chase Chemical Diversity Center, Inc., Pennsylvania Biotechnology Center, 3805 Old Easton Road, Doylestown, Pennsylvania 18902, United States
| | - Jay E. Wrobel
- Fox Chase Chemical Diversity Center, Inc., Pennsylvania Biotechnology Center, 3805 Old Easton Road, Doylestown, Pennsylvania 18902, United States
| | - Allen B. Reitz
- Fox Chase Chemical Diversity Center, Inc., Pennsylvania Biotechnology Center, 3805 Old Easton Road, Doylestown, Pennsylvania 18902, United States
| | - Thomas E. Smithgall
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Suite 523 Bridgeside Point II, 450 Technology Drive, Pittsburgh, Pennsylvania 15219, United States
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12
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Turcu DC, Lillehaug JR, Seo HC. SIX3 and SIX6 interact with GEMININ via C-terminal regions. Biochem Biophys Rep 2019; 20:100695. [PMID: 31844685 PMCID: PMC6895700 DOI: 10.1016/j.bbrep.2019.100695] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 10/09/2019] [Accepted: 10/10/2019] [Indexed: 01/13/2023] Open
Abstract
The histoarchitecture and function of eye and forebrain depend on a well-controlled balance between cell proliferation and differentiation. For example, the binding of the cell cycle regulator GEMININ to CDT1, which is a part of the pre-replication complex, promotes cell differentiation. Homeodomain transcription factors SIX3 and SIX6 also interact with GEMININ of which SIX3-GEMININ interaction promotes cell proliferation, whereas the nature of SIX6-GEMININ interaction has not been studied to date. We investigated SIX3/SIX6 and GEMININ interactions using bimolecular fluorescence complementation, surface plasmon resonance and isothermal titration calorimetry. Interactions between SIX3/SIX6 and GEMININ were detected in mammalian cells in culture. The presence of the C-terminal regions of SIX3 and SIX6 proteins, but not their SIX domains or homeodomains as previously thought, were required for interaction with GEMININ. Interestingly, the disordered C- and N- terminal regions of GEMININ were involved in binding to SIX3/SIX6. The coiled-coil region of GEMININ, which is the known protein-binding domain and also interacts with CDT1, was not involved in GEMININ-SIX3/SIX6 interaction. Using SPR and ITC, SIX3 bound GEMININ with a micromolar affinity and the binding stoichiometry was 1:2 (SIX3 - GEMININ). The present study gives new insights into the binding properties of SIX proteins, especially the role of their variable and disordered C-terminal regions. C-terminal regions of SIX3/SIX6 bind GEMININ. GEMININ coiled-coil region is not involved in SIX3/SIX6 interaction. C- and N-terminal regions of GEMININ bind SIX3/SIX6. SIX3 binds GEMININ with a binding stoichiometry of 1:2.
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Affiliation(s)
- Diana C Turcu
- Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Johan R Lillehaug
- Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Hee-Chan Seo
- Department of Biological Sciences, University of Bergen, Bergen, Norway
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13
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Ye B, Zhou C, Guo H, Zheng M. Effects of BTK signalling in pathogenic microorganism infections. J Cell Mol Med 2019; 23:6522-6529. [PMID: 31397086 PMCID: PMC6787465 DOI: 10.1111/jcmm.14548] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 06/22/2019] [Accepted: 07/02/2019] [Indexed: 02/06/2023] Open
Abstract
As a cytoplasmic protein tyrosine kinase, Bruton's tyrosine kinase (Btk) is widely considered as a vital kinase in many aspects of different physiologic processes. It is engaged in many important signalling pathways related to the immune response, such as the B cell receptor pathway, pattern-recognition receptor pathway, and triggering receptor expressed on myeloid cell pathway. Recent studies have increasingly focused on the important role of Btk in various inflammatory diseases, which are related to Btk expression in myeloid innate immune cells, such as macrophages, dendritic cells and neutrophils. Although some investigations have explored the role of Btk in microbial infections, many aspects remain elusive, and some of the results are opposite and controversial. Considering the complicated and multiple roles of Btk in the immune system, we summarized the engagement of Btk signalling in various pathogenic microorganism infections, the possible mechanisms involved and its therapeutic potential in the control of infectious diseases.
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Affiliation(s)
- Bingjue Ye
- The State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital of School of MedicineZhejiang UniversityHangzhouChina
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious DiseasesHangzhouChina
| | - Cheng Zhou
- The State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital of School of MedicineZhejiang UniversityHangzhouChina
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious DiseasesHangzhouChina
| | - Huiting Guo
- The State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital of School of MedicineZhejiang UniversityHangzhouChina
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious DiseasesHangzhouChina
| | - Min Zheng
- The State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital of School of MedicineZhejiang UniversityHangzhouChina
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious DiseasesHangzhouChina
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14
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Andreotti AH, Joseph RE, Conley JM, Iwasa J, Berg LJ. Multidomain Control Over TEC Kinase Activation State Tunes the T Cell Response. Annu Rev Immunol 2019; 36:549-578. [PMID: 29677469 DOI: 10.1146/annurev-immunol-042617-053344] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Signaling through the T cell antigen receptor (TCR) activates a series of tyrosine kinases. Directly associated with the TCR, the SRC family kinase LCK and the SYK family kinase ZAP-70 are essential for all downstream responses to TCR stimulation. In contrast, the TEC family kinase ITK is not an obligate component of the TCR cascade. Instead, ITK functions as a tuning dial, to translate variations in TCR signal strength into differential programs of gene expression. Recent insights into TEC kinase structure have provided a view into the molecular mechanisms that generate different states of kinase activation. In resting lymphocytes, TEC kinases are autoinhibited, and multiple interactions between the regulatory and kinase domains maintain low activity. Following TCR stimulation, newly generated signaling modules compete with the autoinhibited core and shift the conformational ensemble to the fully active kinase. This multidomain control over kinase activation state provides a structural mechanism to account for ITK's ability to tune the TCR signal.
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Affiliation(s)
- Amy H Andreotti
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa 50011, USA; ,
| | - Raji E Joseph
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa 50011, USA; ,
| | - James M Conley
- Department of Pathology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA; ,
| | - Janet Iwasa
- Department of Biochemistry, University of Utah, Salt Lake City, Utah 84112, USA;
| | - Leslie J Berg
- Department of Pathology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA; ,
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15
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Agosto LM, Henderson AJ. CD4 + T Cell Subsets and Pathways to HIV Latency. AIDS Res Hum Retroviruses 2018; 34:780-789. [PMID: 29869531 DOI: 10.1089/aid.2018.0105] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Latent infection of CD4+ T cells is the main barrier to eradicating HIV-1 infection from infected patients. The cellular and molecular mechanisms involved in the establishment and maintenance of latent infection are directly linked to the transcriptional program of the different CD4+ T cell subsets targeted by the virus. In this review, we provide an overview of how T cell activation, T cell differentiation into functional subsets, and the mode of initial viral infection influence HIV proviral transcription and entry into latency.
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Affiliation(s)
- Luis M. Agosto
- Section of Infectious Diseases, Department of Medicine, Boston University Medical Center, Boston, Massachusetts
| | - Andrew J. Henderson
- Section of Infectious Diseases, Department of Medicine, Boston University Medical Center, Boston, Massachusetts
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16
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Wang F, Zhang W, Wang C, Fang X, Cheng H, Liu S, Chen XL. Inhibitor of Tec kinase, LFM-A13, decreases pro-inflammatory mediators production in LPS-stimulated RAW264.7 macrophages via NF-κB pathway. Oncotarget 2018; 8:34099-34110. [PMID: 28415764 PMCID: PMC5470954 DOI: 10.18632/oncotarget.16212] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 03/03/2017] [Indexed: 11/25/2022] Open
Abstract
Tec kinase, a prototypical member of the Tec tyrosine kinases family, was shown to mainly govern lymphocyte proliferation. In the present study, we investigated the role of Tec kinase in acute inflammatory response in lipopolysaccharide (LPS) challenge. First, we demonstrate that Tec kinase activity was observed in RAW264.7 macrophages exposed to LPS. Tec and phosphorylated Tec expression were upregulated in a dose- and time-dependent manner after LPS stimulation. LPS increased monocyte chemotactic protein (MCP)-1 secretion and intercellular adhesion molecule (ICAM)-1 expression, and increasing mRNA expression was consistently observed. LPS also induced IκBα phoshporylaytion and its degradation, increased NF-κB p65 phoshporylaytion and translocation to nuclei in RAW264.7 cells. Pretreatment with LFM-A13 decreased LPS-induced cytokines and chemokines production and mRNA levels, blocked NF-κB transactivation. These effects of LPS were also prevented by Tec-siRNA. Additionally, LFM-A13 or Tec-siRNA obviously inhibited LPS-induced TGFβ-activated kinase 1(TAK1) phosphorylation. Taken together, our results suggest that Tec kinase involves in acute inflammation process in LPS-stimulated RAW264.7 cells, at least mediated by activating TAK1/ NF-κB signal pathway.
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Affiliation(s)
- Fei Wang
- Department of Burns, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, PR China
| | - Wei Zhang
- Department of Nephrology, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, PR China
| | - Chao Wang
- Department of Burns, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, PR China
| | - Xu Fang
- Department of Burns, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, PR China
| | - Hao Cheng
- Department of Burns, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, PR China
| | - Sheng Liu
- Department of Burns, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, PR China
| | - Xu-Lin Chen
- Department of Burns, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, PR China
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17
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IL-2 Inducible Kinase ITK is Critical for HIV-1 Infection of Jurkat T-cells. Sci Rep 2018; 8:3217. [PMID: 29453458 PMCID: PMC5816632 DOI: 10.1038/s41598-018-21344-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 01/15/2018] [Indexed: 01/04/2023] Open
Abstract
Successful replication of Human immunodeficiency virus (HIV)-1 depends on the expression of various cellular host factors, such as the interleukin-2 inducible T-cell kinase (ITK), a member of the protein family of TEC-tyrosine kinases. ITK is selectively expressed in T-cells and coordinates signaling pathways downstream of the T-cell receptor and chemokine receptors, including PLC-1 activation, Ca2+-release, transcription factor mobilization, and actin rearrangements. The exact role of ITK during HIV-1 infection is still unknown. We analyzed the function of ITK during HIV-1 replication and showed that attachment, fusion of virions with the cell membrane and entry into Jurkat T-cells was inhibited when ITK was knocked down. In contrast, reverse transcription and provirus expression were not affected by ITK deficiency. Inhibited ITK expression did not affect the CXCR4 receptor on the cell surface, whereas CD4 and LFA-1 integrin levels were slightly enhanced in ITK knockdown cells and heparan sulfate (HS) expression was completely abolished in ITK depleted T-cells. However, neither HS expression nor other attachment factors could explain the impaired HIV-1 binding to ITK-deficient cells, which suggests that a more complex cellular process is influenced by ITK or that not yet discovered molecules contribute to restriction of HIV-1 binding and entry.
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18
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Wu M, Alvarado JJ, Augelli-Szafran CE, Ptak RG, Smithgall TE. A single β-octyl glucoside molecule induces HIV-1 Nef dimer formation in the absence of partner protein binding. PLoS One 2018; 13:e0192512. [PMID: 29415006 PMCID: PMC5802939 DOI: 10.1371/journal.pone.0192512] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 01/24/2018] [Indexed: 01/05/2023] Open
Abstract
The HIV-1 Nef accessory protein is essential for viral pathogenicity and AIDS progression. Nef forms complexes with multiple host cell factors to facilitate viral replication and promote immune escape of HIV-infected cells. Previous X-ray crystal structures demonstrate that Nef forms homodimers, the orientation of which are influenced by host cell binding partners. In cell-based fluorescence complementation assays, Nef forms homodimers at the plasma membrane. However, recombinant Nef proteins often exist as monomers in solution, suggesting that membrane interaction may also trigger monomer to dimer transitions. In this study, we show that monomeric Nef core proteins can be induced to form dimers in the presence of low concentrations of the non-ionic surfactant, β-octyl glucoside (βOG). X-ray crystallography revealed that a single βOG molecule is present in the Nef dimer, with the 8-carbon acyl chain of the ligand binding to a hydrophobic pocket formed by the dimer interface. This Nef-βOG dimer interface involves helix αB, as observed in previous dimer structures, as well as a helix formed by N-terminal residues 54-66. Nef dimer formation is stabilized in solution by the addition of βOG, providing biochemical validation for the crystal structure. These observations together suggest that the interaction with host cell lipid mediators or other hydrophobic ligands may play a role in Nef dimerization, which has been previously linked to multiple Nef functions including host cell protein kinase activation, CD4 downregulation, and enhancement of HIV-1 replication.
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Affiliation(s)
- Mousheng Wu
- Department of Chemistry, Drug Discovery Division, Southern Research Institute, Birmingham, AL, United States of America
| | - John J. Alvarado
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America
| | - Corinne E. Augelli-Szafran
- Department of Chemistry, Drug Discovery Division, Southern Research Institute, Birmingham, AL, United States of America
| | - Roger G. Ptak
- Department of Infectious Disease Research, Southern Research Institute, Frederick, MD, United States of America
| | - Thomas E. Smithgall
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America
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19
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Moroco JA, Alvarado JJ, Staudt RP, Shi H, Wales TE, Smithgall TE, Engen JR. Remodeling of HIV-1 Nef Structure by Src-Family Kinase Binding. J Mol Biol 2018; 430:310-321. [PMID: 29258818 PMCID: PMC5801098 DOI: 10.1016/j.jmb.2017.12.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 12/07/2017] [Accepted: 12/10/2017] [Indexed: 11/25/2022]
Abstract
The HIV-1 accessory protein Nef controls multiple aspects of the viral life cycle and host immune response, making it an attractive therapeutic target. Previous X-ray crystal structures of Nef in complex with key host cell binding partners have shed light on protein-protein interactions critical to Nef function. Crystal structures of Nef in complex with either the SH3 or tandem SH3-SH2 domains of Src-family kinases reveal distinct dimer conformations of Nef. However, the existence of these Nef dimer complexes in solution has not been established. Here we used hydrogen exchange mass spectrometry (HX MS) to compare the solution conformation of Nef alone and in complexes with the SH3 or the SH3-SH2 domains of the Src-family kinase Hck. HX MS revealed that interaction with the Hck SH3 or tandem SH3-SH2 domains induces protection of the Nef αB-helix from deuterium uptake, consistent with a role for αB in dimer formation. HX MS analysis of a Nef mutant (position Asp123, a site buried in the Nef:SH3 dimer but surface exposed in the Nef:SH3-SH2 complex), showed a Hck-induced conformational change in Nef relative to wild-type Nef. These results support a model in which Src-family kinase binding induces conformational changes in Nef to expose residues critical for interaction with the μ1 subunit of adaptor protein 1 and the major histocompatibility complex-1 tail, and subsequent major histocompatibility complex-1 downregulation and immune escape of HIV-infected cells required for functional interactions with downstream binding partners.
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Affiliation(s)
- Jamie A Moroco
- Department of Chemistry and Chemical Biology, Maildrop 412TF, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA.
| | - John Jeff Alvarado
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Bridgeside Point II, Suite 523, 450 Technology Drive, Pittsburgh, PA 15219, USA.
| | - Ryan P Staudt
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Bridgeside Point II, Suite 523, 450 Technology Drive, Pittsburgh, PA 15219, USA.
| | - Haibin Shi
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Bridgeside Point II, Suite 523, 450 Technology Drive, Pittsburgh, PA 15219, USA.
| | - Thomas E Wales
- Department of Chemistry and Chemical Biology, Maildrop 412TF, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA.
| | - Thomas E Smithgall
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Bridgeside Point II, Suite 523, 450 Technology Drive, Pittsburgh, PA 15219, USA.
| | - John R Engen
- Department of Chemistry and Chemical Biology, Maildrop 412TF, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA.
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20
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von Raußendorf F, de Ruiter A, Leonard TA. A switch in nucleotide affinity governs activation of the Src and Tec family kinases. Sci Rep 2017; 7:17405. [PMID: 29234112 PMCID: PMC5727165 DOI: 10.1038/s41598-017-17703-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 11/29/2017] [Indexed: 11/10/2022] Open
Abstract
The Tec kinases, closely related to Src family kinases, are essential for lymphocyte function in the adaptive immune system. Whilst the Src and Abl kinases are regulated by tail phosphorylation and N-terminal myristoylation respectively, the Tec kinases are notable for the absence of either regulatory element. We have found that the inactive conformations of the Tec kinase Itk and Src preferentially bind ADP over ATP, stabilising both proteins. We demonstrate that Itk adopts the same conformation as Src and that the autoinhibited conformation of Src is independent of its C-terminal tail. Allosteric activation of both Itk and Src depends critically on the disruption of a conserved hydrophobic stack that accompanies regulatory domain displacement. We show that a conformational switch permits the exchange of ADP for ATP, leading to efficient autophosphorylation and full activation. In summary, we propose a universal mechanism for the activation and autoinhibition of the Src and Tec kinases.
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Affiliation(s)
- Freia von Raußendorf
- Department of Structural and Computational Biology, Max F. Perutz Laboratories (MFPL), Campus Vienna Biocenter 5, 1030, Vienna, Austria
| | - Anita de Ruiter
- Institute of Molecular Modeling and Simulation, University of Natural Resources and Life Sciences (BOKU), 1190, Vienna, Austria
| | - Thomas A Leonard
- Department of Structural and Computational Biology, Max F. Perutz Laboratories (MFPL), Campus Vienna Biocenter 5, 1030, Vienna, Austria.
- Department of Medical Biochemistry, Medical University of Vienna, 1090, Vienna, Austria.
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21
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Shu ST, Emert-Sedlak LA, Smithgall TE. Cell-based Fluorescence Complementation Reveals a Role for HIV-1 Nef Protein Dimerization in AP-2 Adaptor Recruitment and CD4 Co-receptor Down-regulation. J Biol Chem 2016; 292:2670-2678. [PMID: 28031466 DOI: 10.1074/jbc.m116.770016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 12/21/2016] [Indexed: 02/03/2023] Open
Abstract
The HIV-1 Nef accessory factor enhances viral infectivity, immune evasion, and AIDS progression. Nef triggers rapid down-regulation of CD4 via the endocytic adaptor protein 2 (AP-2) complex, a process linked to enhanced viral infectivity and immune escape. Here, we describe a bimolecular fluorescence complementation (BiFC) assay to visualize the interaction of Nef with AP-2 and CD4 in living cells. Interacting protein pairs were fused to complementary non-fluorescent fragments of YFP and co-expressed in 293T cells. Nef interactions with both CD4 and AP-2 resulted in complementation of YFP and a bright fluorescent signal by confocal microcopy that localized to the cell periphery. Co-expression of the AP-2 α subunit enhanced the Nef·AP-2 σ2 subunit BiFC signal and vice versa, suggesting that the AP-2 α-σ2 hemicomplex interacts cooperatively with Nef. Mutagenesis of Nef amino acids Arg-134, Glu-174, and Asp-175, which stabilize Nef for AP-2 α-σ2 binding in a recent co-crystal structure, substantially reduced AP-2 interaction without affecting CD4 binding. A dimerization-defective mutant of Nef failed to interact with either CD4 or AP-2 in the BiFC assay, indicating that Nef quaternary structure is required for CD4 and AP-2 recruitment as well as CD4 down-regulation. A small molecule previously shown to bind the Nef dimerization interface also reduced Nef interactions with AP-2 and CD4 and restored CD4 expression to the surface of HIV-infected cells. Our findings provide a mechanistic explanation for previous observations that dimerization-defective Nef mutants fail to down-regulate CD4 and validate the Nef dimerization interface as a target site for antiretroviral drug development.
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Affiliation(s)
- Sherry T Shu
- From the Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15219
| | - Lori A Emert-Sedlak
- From the Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15219
| | - Thomas E Smithgall
- From the Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15219
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22
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Saxena D, Spino M, Tricta F, Connelly J, Cracchiolo BM, Hanauske AR, D’Alliessi Gandolfi D, Mathews MB, Karn J, Holland B, Park MH, Pe’ery T, Palumbo PE, Hanauske-Abel HM. Drug-Based Lead Discovery: The Novel Ablative Antiretroviral Profile of Deferiprone in HIV-1-Infected Cells and in HIV-Infected Treatment-Naive Subjects of a Double-Blind, Placebo-Controlled, Randomized Exploratory Trial. PLoS One 2016; 11:e0154842. [PMID: 27191165 PMCID: PMC4871512 DOI: 10.1371/journal.pone.0154842] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 04/18/2016] [Indexed: 01/19/2023] Open
Abstract
UNLABELLED Antiretrovirals suppress HIV-1 production yet spare the sites of HIV-1 production, the HIV-1 DNA-harboring cells that evade immune detection and enable viral resistance on-drug and viral rebound off-drug. Therapeutic ablation of pathogenic cells markedly improves the outcome of many diseases. We extend this strategy to HIV-1 infection. Using drug-based lead discovery, we report the concentration threshold-dependent antiretroviral action of the medicinal chelator deferiprone and validate preclinical findings by a proof-of-concept double-blind trial. In isolate-infected primary cultures, supra-threshold concentrations during deferiprone monotherapy caused decline of HIV-1 RNA and HIV-1 DNA; did not allow viral breakthrough for up to 35 days on-drug, indicating resiliency against viral resistance; and prevented, for at least 87 days off-drug, viral rebound. Displaying a steep dose-effect curve, deferiprone produced infection-independent deficiency of hydroxylated hypusyl-eIF5A. However, unhydroxylated deoxyhypusyl-eIF5A accumulated particularly in HIV-infected cells; they preferentially underwent apoptotic DNA fragmentation. Since the threshold, ascertained at about 150 μM, is achievable in deferiprone-treated patients, we proceeded from cell culture directly to an exploratory trial. HIV-1 RNA was measured after 7 days on-drug and after 28 and 56 days off-drug. Subjects who attained supra-threshold concentrations in serum and completed the protocol of 17 oral doses, experienced a zidovudine-like decline of HIV-1 RNA on-drug that was maintained off-drug without statistically significant rebound for 8 weeks, over 670 times the drug's half-life and thus clearance from circulation. The uniform deferiprone threshold is in agreement with mapping of, and crystallographic 3D-data on, the active site of deoxyhypusyl hydroxylase (DOHH), the eIF5A-hydroxylating enzyme. We propose that deficiency of hypusine-containing eIF5A impedes the translation of mRNAs encoding proline cluster ('polyproline')-containing proteins, exemplified by Gag/p24, and facilitated by the excess of deoxyhypusine-containing eIF5A, releases the innate apoptotic defense of HIV-infected cells from viral blockade, thus depleting the cellular reservoir of HIV-1 DNA that drives breakthrough and rebound. TRIAL REGISTRATION ClinicalTrial.gov NCT02191657.
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Affiliation(s)
- Deepti Saxena
- Department of Pediatrics, New Jersey Medical School, Rutgers University, Newark, New Jersey, United States of America
| | - Michael Spino
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
- ApoPharma Inc., Toronto, Ontario, Canada
| | | | | | - Bernadette M. Cracchiolo
- Department of Obstetrics, Gynecology and Women’s Health, New Jersey Medical School, Rutgers University, Newark, New Jersey, United States of America
| | - Axel-Rainer Hanauske
- Oncology Center and Medical Clinic III, Asklepios Klinik St. Georg, Hamburg, Germany
| | | | - Michael B. Mathews
- Department of Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey, United States of America
| | - Jonathan Karn
- Department of Molecular Biology and Microbiology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Bart Holland
- Department of Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey, United States of America
| | - Myung Hee Park
- Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, Maryland, United States of America
| | - Tsafi Pe’ery
- Department of Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey, United States of America
| | - Paul E. Palumbo
- Department of Pediatrics, New Jersey Medical School, Rutgers University, Newark, New Jersey, United States of America
- * E-mail: (PEP); (HMHA)
| | - Hartmut M. Hanauske-Abel
- Department of Pediatrics, New Jersey Medical School, Rutgers University, Newark, New Jersey, United States of America
- Department of Obstetrics, Gynecology and Women’s Health, New Jersey Medical School, Rutgers University, Newark, New Jersey, United States of America
- Department of Microbiology, Biochemistry and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey, United States of America
- * E-mail: (PEP); (HMHA)
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23
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Roberts JM, Tarafdar S, Joseph RE, Andreotti AH, Smithgall TE, Engen JR, Wales TE. Dynamics of the Tec-family tyrosine kinase SH3 domains. Protein Sci 2016; 25:852-64. [PMID: 26808198 DOI: 10.1002/pro.2887] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 01/13/2016] [Accepted: 01/19/2016] [Indexed: 11/10/2022]
Abstract
The Src Homology 3 (SH3) domain is an important regulatory domain found in many signaling proteins. X-ray crystallography and NMR structures of SH3 domains are generally conserved but other studies indicate that protein flexibility and dynamics are not. We previously reported that based on hydrogen exchange mass spectrometry (HX MS) studies, there is variable flexibility and dynamics among the SH3 domains of the Src-family tyrosine kinases and related proteins. Here we have extended our studies to the SH3 domains of the Tec family tyrosine kinases (Itk, Btk, Tec, Txk, Bmx). The SH3 domains of members of this family augment the variety in dynamics observed in previous SH3 domains. Txk and Bmx SH3 were found to be highly dynamic in solution by HX MS and Bmx was unstructured by NMR. Itk and Btk SH3 underwent a clear EX1 cooperative unfolding event, which was localized using pepsin digestion and mass spectrometry after hydrogen exchange labeling. The unfolding was localized to peptide regions that had been previously identified in the Src-family and related protein SH3 domains, yet the kinetics of unfolding were not. Sequence alignment does not provide an easy explanation for the observed dynamics behavior, yet the similarity of location of EX1 unfolding suggests that higher-order structural properties may play a role. While the exact reason for such dynamics is not clear, such motions can be exploited in intra- and intermolecular binding assays of proteins containing the domains.
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Affiliation(s)
- Justin M Roberts
- Department of Chemistry & Chemical Biology, Northeastern University, Boston, Massachusetts, 02115
| | - Sreya Tarafdar
- Department of Microbiology & Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15219
| | - Raji E Joseph
- Roy J. Carver Department of Biochemistry, Biophysics & Molecular Biology, Iowa State University, Ames, Iowa, 50011
| | - Amy H Andreotti
- Roy J. Carver Department of Biochemistry, Biophysics & Molecular Biology, Iowa State University, Ames, Iowa, 50011
| | - Thomas E Smithgall
- Department of Microbiology & Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15219
| | - John R Engen
- Department of Chemistry & Chemical Biology, Northeastern University, Boston, Massachusetts, 02115
| | - Thomas E Wales
- Department of Chemistry & Chemical Biology, Northeastern University, Boston, Massachusetts, 02115
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24
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Kokhaei P, Jadidi-Niaragh F, Sotoodeh Jahromi A, Osterborg A, Mellstedt H, Hojjat-Farsangi M. Ibrutinib-A double-edge sword in cancer and autoimmune disorders. J Drug Target 2015; 24:373-85. [DOI: 10.3109/1061186x.2015.1086357] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Parviz Kokhaei
- Cancer Research Center and Department of Immunology, Semnan University of Medical Sciences, Semnan, Iran,
- Department of Oncology-Pathology, Immune and Gene therapy Lab, Cancer Center Karolinska (CCK), Karolinska University Hospital Solna and Karolinska Institute, Stockholm, Sweden,
| | - Farhad Jadidi-Niaragh
- Department of Immunology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran,
| | | | - Anders Osterborg
- Department of Oncology-Pathology, Immune and Gene therapy Lab, Cancer Center Karolinska (CCK), Karolinska University Hospital Solna and Karolinska Institute, Stockholm, Sweden,
- Departments of Hematology and Oncology, Karolinska University Hospital Solna, Stockholm, Sweden, and
| | - Håkan Mellstedt
- Department of Oncology-Pathology, Immune and Gene therapy Lab, Cancer Center Karolinska (CCK), Karolinska University Hospital Solna and Karolinska Institute, Stockholm, Sweden,
- Departments of Hematology and Oncology, Karolinska University Hospital Solna, Stockholm, Sweden, and
| | - Mohammad Hojjat-Farsangi
- Department of Oncology-Pathology, Immune and Gene therapy Lab, Cancer Center Karolinska (CCK), Karolinska University Hospital Solna and Karolinska Institute, Stockholm, Sweden,
- Department of Immunology, School of Medicine, Bushehr University of Medical Sciences, Bushehr, Iran
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25
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Hojjat-Farsangi M. Targeting non-receptor tyrosine kinases using small molecule inhibitors: an overview of recent advances. J Drug Target 2015. [DOI: 10.3109/1061186x.2015.1068319] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Mohammad Hojjat-Farsangi
- Department of Oncology-Pathology, Immune and Gene Therapy Lab, Cancer Center Karolinska (CCK), Karolinska University Hospital Solna and Karolinska Institute, Stockholm, Sweden and
- Department of Immunology, School of Medicine, Bushehr University of Medical Sciences, Bushehr, Iran
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